To enhance the Young’s modulus(E)and strength of titanium alloys,we designed titanium matrix composites with intercon-nected microstructure based on the Hashin-Shtrikman theory.According to the results,the in-situ re...To enhance the Young’s modulus(E)and strength of titanium alloys,we designed titanium matrix composites with intercon-nected microstructure based on the Hashin-Shtrikman theory.According to the results,the in-situ reaction yielded an interconnected microstructure composed of Ti_(2)C particles when the Ti_(2)C content reached 50vol%.With widths of 10 and 230 nm,the intraparticle Ti lamellae in the prepared composite exhibited a bimodal size distribution due to precipitation and the unreacted Ti phase within the grown Ti_(2)C particles.The composites with interconnected microstructure attained superior properties,including E of 174.3 GPa and ultimate flexural strength of 1014 GPa.Compared with that of pure Ti,the E of the composite was increased by 55% due to the high Ti_(2)C content and interconnected microstructure.The outstanding strength resulted from the strong interfacial bonding,load-bearing capacity of interconnected Ti_(2)C particles,and bimodal intraparticle Ti lamellae,which minimized the average crack driving force.Interrupted flexural tests revealed preferential crack initiation along the{001}cleavage plane and grain boundary of Ti_(2)C in the region with the highest tensile stress.In addition,the propagation can be efficiently inhibited by interparticle Ti grains,which prevented the brittle fracture of the composites.展开更多
Like other manufacturing techniques,plasma spraying has also a non-linear behavior because of the contribution of many coating variables.This characteristic results in finding optimal factor combination difficult.Subs...Like other manufacturing techniques,plasma spraying has also a non-linear behavior because of the contribution of many coating variables.This characteristic results in finding optimal factor combination difficult.Subsequently,the issue can be solved through effective and strategic statistical procedures integrated with systematic experimental data.Plasma spray parameters such as power,stand-off distance and powder feed rate have significant influence on coating characteristics like Young’s modulus.This paper presents the use of statistical techniques in specifically response surface methodology(RSM),analysis of variance,and regression analysis to develop empirical relationship to predict Young’s modulus of plasma-sprayed alumina coatings.The developed empirical relationships can be effectively used to predict Young’s modulus of plasma-sprayed alumina coatings at 95%confidence level.Response graphs and contour plots were constructed to identify the optimum plasma spray parameters to attain maximum Young’s modulus in alumina coatings.A linear regression relationship was established between porosity and Young’s modulus of the alumina coatings.展开更多
The elastic-plastic indentation properties of materials with varying ratio of hardness to Young’s modulus(H/E) were analyzed with the finite element method. And the indentation stress fields of materials with varying...The elastic-plastic indentation properties of materials with varying ratio of hardness to Young’s modulus(H/E) were analyzed with the finite element method. And the indentation stress fields of materials with varying ratio H/E on the surface were studied by the experiment. The results show that the penetration depth, contact radius, plastic pile-up and the degree of elastic recovery depend strongly on the ratio H/E. Moreover, graphs were established to describe the relationship between the elastic-plastic indentation parameters and H/E. The established graphs can be used to predict the H/E of materials when compared with experimental data.展开更多
The Young’s modulus was measured at high temperatures by impulse excitation of vibration method,and the effects of heating rate,holding time and temperature cycle on the test results were analyzed.The results show th...The Young’s modulus was measured at high temperatures by impulse excitation of vibration method,and the effects of heating rate,holding time and temperature cycle on the test results were analyzed.The results show that the heating rate has obvious effect on the high temperature Young’s modulus of the green body,but has no obvious effect on that of the sintered products;the holding time of the heating process has no regular effect on the Young’s modulus,and the effect varies with the different products at a certain temperature;the method can also be used to test the Young’s modulus during cooling process.展开更多
Introduction: To investigate a long-term in vivo deterioration of polymethylmethacrylate (PMMA) bone cement over time, we evaluated retrieved PMMA cement in terms of chemical elements presenting in the cement using en...Introduction: To investigate a long-term in vivo deterioration of polymethylmethacrylate (PMMA) bone cement over time, we evaluated retrieved PMMA cement in terms of chemical elements presenting in the cement using energy dispersive analysis of X-rays;Knoop hardness;and the Young’s modulus using scanning acoustic microscopy. Materials and Methods: For mechanical evaluation, we could neglect the influences of entrapped air bubbles or blood by the use of small specimens. The study was based on thirteen cement samples (six used in the acetabulum and seven in the femur) derived from eight patients (age at revision surgery: mean 72.5, range 68 to 79). All of these samples were Simplex-P?cement. They were functioning well at least ten years after the previous surgery. Duration until revision surgery was ranged 12 to 25 years (average, 17.4 years). The reason for revision was aseptic mechanical loosening. Twenty samples of Simplex-Preg;cement were served by manually mixing as a control. Results: The average of the hardness of the cement was 17.0 ± 1.2 (range, 13.4-20.6). In the control, the hardness was 17.8 ± 1.5 (range, 14.0-24.6). There was no significant difference between these values. The mean of Young’s modulus of the cement was 5.61 ± 0.19 GPa (range, 5.09-6.10). In the control, the modulus was 6.04 ± 0.13 GPa (range, 5.68-6.45). Although the modulus was significantly less than that of the control, there was only 7% decrease in average between twelve and twenty-five years in vivo. Conclusions: Our results suggest that long-term implantation and functional loading in vivo may not be the limiting factor in the mechanical integrity of the bone cement.展开更多
In this paper, we will study the most important effects in the nano-scale resonator: the coupling effect of temperature and strain rate, and the non-Fourier effect in heat conduction. A solution for the generalized th...In this paper, we will study the most important effects in the nano-scale resonator: the coupling effect of temperature and strain rate, and the non-Fourier effect in heat conduction. A solution for the generalized thermoelastic vibration of nano-resonator induced by thermal loading has been developed. The Young’s modulus is taken as a linear function of the reference temperature. The effects of the thermal loading and the reference temperature in all the studied fields have been studied and represented in graphs with some comparisons. The Young’s modulus makes significant effects on all the studied fields where the values of the temperature, the vibration of the deflection, stress, displacement, strain, stress-strain energy increase when the Young’s modulus has taken to be variable.展开更多
For decades,it has been well accepted that every 1 wt.%Li addition to Al will reduce Al alloy’s density by 3%and increase its Young’s modulus by 6%.However,the fundamental mechanism of modulus improve-ments stays co...For decades,it has been well accepted that every 1 wt.%Li addition to Al will reduce Al alloy’s density by 3%and increase its Young’s modulus by 6%.However,the fundamental mechanism of modulus improve-ments stays controversial though all studies agreed that the contribution of such a substantial boosting comes from Li-rich clusters either in solid solution or precipitations.In this study,we experimentally produce nano-sized Li-rich clusters by non-equilibrium solidification using centrifugal casting and trace their evolutions as a function of subsequent heat treatments.High-resolution transmission electron mi-croscopy(HRTEM)reveals a further decrease in the lattice constants of Li-rich regions from the as-cast(0.406 nm),solid solution(0.405 nm)to the aged state(0.401 nm),while Young’s modulus of the Al-Li al-loy reaches 89.16 GPa.Small-angle neutron scattering(SANS)experiments and first-principle calculations based on density functional theory have shown both the bond strength around precipitates and the size of those Li-rich region dominate Young’s modulus.At the beginning,it is volumetric compression due to Li addition that increases modulus,tightening the Al-Al potential curves.In the end,it is the Al-Al and Al-Li valence bonds in Al 3 Li at large size and high-volume fraction which increase its second derivative of internal energy and thus Young’s modulus.展开更多
Stress shielding is caused by the mismatch of stiffness between bone and implant materials,which may give rise to bone resorption and loosening,thereby causing implantation failure.There is a huge gap between Young’s...Stress shielding is caused by the mismatch of stiffness between bone and implant materials,which may give rise to bone resorption and loosening,thereby causing implantation failure.There is a huge gap between Young’s modulus of human bone and low Young’s modulusβTi alloys.A porous structure design can achieve the target of low Young’s modulus,and thus achieve the matching between human bone and implant materials.However,a suitable space holder(SH)that can be applied at high temperatures and sintering pressure has not been reported.In this study,the TiZrNbTa/Ti titanium matrix composite(TMC)with high strength and large ductility was used as scaffold materials and combined the SH technique with the spark plasma sintering(SPS)technique to obtain a porous structure.A novel space holder,i.e.,MgO particles was adopted,which can withstand high-temperature sintering accompanied by a sintering pressure.The porous TiZrNbTa/Ti with 40 vol.%MgO added exhibits a maximum strength of 345.9±10.4 MPa and Young’s modulus of 24.72±0.20 GPa,respectively.It possesses higher strength compared with human bone and matches Young’s modulus of human bone,which exhibits great potential for clinical application.展开更多
To get the quantitive value of abnormal biological tissues, an inverse algorithm about the Young＇s modulus based on the boundary extraction and the image registration technologies is proposed. With the known displace...To get the quantitive value of abnormal biological tissues, an inverse algorithm about the Young＇s modulus based on the boundary extraction and the image registration technologies is proposed. With the known displacements of boundary tissues and the force distribution, the Young＇s modulus is calculated by constructing the unit system and the inverse finite element method （IFEM）. Then a tough range of the modulus for the whole tissue is estimated referring the value obtained before. The improved particle swarm optimizer （PSO） method is adopted to calculate the whole Yong＇s modulus distribution. The presented algorithm overcomes some limitations in other Young＇s modulus reconstruction methods and relaxes the displacements and force boundary condition requirements. The repetitious numerical simulation shows that errors in boundary displacement are not very sensitive to the estimation of next process; a final feasible solution is obtained by the improved PSO method which is close to the theoretical values obtained during searching in an extensive range.展开更多
The effect of mechanical strength of the dispersed particle gel(DPG)on its macro plugging performance is significant,however,little study has been reported.In this paper,DPG particles with different mechanical strengt...The effect of mechanical strength of the dispersed particle gel(DPG)on its macro plugging performance is significant,however,little study has been reported.In this paper,DPG particles with different mechanical strengths were obtained by mechanical shearing of bulk gels prepared with different formula.Young’s moduli of DPG particles on the micro and nano scales were measured by atomic force microscope for the first time.The mapping relationship among the formula of bulk gel,the Young’s moduli of the DPG particles and the final plugging performance were established.The results showed that when the Young’s moduli of the DPG particles increased from 82 to 328 Pa,the plugging rate increased significantly from 91.46%to 97.10%due to the distinctly enhanced stacking density and strength at this range.While when the Young’s moduli of the DPG particles surpassed 328 Pa,the further increase of plugging rate with the Young’s moduli of the DPG particles became insignificant.These results indicated that the improvement of plugging rate was more efficient by adjusting the Young’s moduli of the DPG particles within certain ranges,providing guidance for improving the macroscopic application properties of DPG systems in reservoir heterogeneity regulation.展开更多
Young’s modulus of New Red Sandstone was investigated experimentally to gain insight into its nonlinear nature.A large experimental programme was carried out by applying a controllable quasi-static and dynamic uniaxi...Young’s modulus of New Red Sandstone was investigated experimentally to gain insight into its nonlinear nature.A large experimental programme was carried out by applying a controllable quasi-static and dynamic uniaxial loading to 286 dry sandstone samples of four different sizes.The static and dynamic tests,similar to those aiming at determining the uniaxial compressive strength,were conducted using the state-of-the-art experimental facilities at the University of Aberdeen including a custom-built small experimental rig for inducing a dynamic uniaxial compressive load via a piezoelectric transducer.The obtained results have confirmed a complex nature of Young’s modulus of sandstone.Specifically,under a harmonic dynamic loading,it shows strongly nonlinear behaviour,which is hardening and softening with respect to frequency and amplitude of the dynamic loading,respectively.展开更多
It is difficult to establish structure-property relationships in a defective solid because of its inhomogeneous-geometry microstructure caused by defects. In the present research, the effects of pores and cracks on th...It is difficult to establish structure-property relationships in a defective solid because of its inhomogeneous-geometry microstructure caused by defects. In the present research, the effects of pores and cracks on the Young’s modulus of a defective solid are studied. Based on the law of the conservation of energy, mathematical formulations are proposed to indicate how the shape, size, and distribution of defects affect the effective Young’s modulus. In this approach, detailed equations are illustrated to represent the shape and size of defects on the effective Young’s modulus. Different from the results obtained from the traditional empirical analyses, mixture law or statistical method, for the first time, our results from the finite element method （FEM） and strict analytical calculation show that the influence of pore radius and crack length on the effective Young’s modulus can be quantified. It is found that the longest crack in a typical microstructure of ceramic coating dominates the contribution of the effective Young’s modulus in the vertical direction of the crack.展开更多
Background:Apparent Young’s modulus(AYM),which reflects the fundamental mechanical property of live cells measured by atomic force microscopy and is determined by substrate stiffness regulated cytoskeletal organizati...Background:Apparent Young’s modulus(AYM),which reflects the fundamental mechanical property of live cells measured by atomic force microscopy and is determined by substrate stiffness regulated cytoskeletal organization,has been investigated as potential indicators of cell fate in specific cell types.However,applying biophysical cues,such as modulating the substrate stiffness,to regulate AYM and thereby reflect and/or control stem cell lineage specificity for downstream applications,remains a primary challenge during in vitro stem cell expansion.Moreover,substrate stiffness could modulate cell heterogeneity in the single-cell stage and contribute to cell fate regulation,yet the indicative link between AYM and cell fate determination during in vitro dynamic cell expansion(from single-cell stage to multi-cell stage)has not been established.Results:Here,we show that the AYM of cells changed dynamically during passaging and proliferation on substrates with different stiffness.Moreover,the same change in substrate stiffness caused different patterns of AYM change in epithelial and mesenchymal cell types.Embryonic stem cells and their derived progenitor cells exhibited distinguishing AYM changes in response to different substrate stiffness that had significant effects on their maintenance of pluripotency and/or lineage-specific characteristics.On substrates that were too rigid or too soft,fluctuations in AYM occurred during cell passaging and proliferation that led to a loss in lineage specificity.On a substrate with‘optimal’stiffness(i.e.,3.5 kPa),the AYM was maintained at a constant level that was consistent with the parental cells during passaging and proliferation and led to preservation of lineage specificity.The effects of substrate stiffness on AYM and downstream cell fate were correlated with intracellular cytoskeletal organization and nuclear/cytoplasmic localization of YAP.Conclusions:In summary,this study suggests that optimal substrate stiffness regulated consistent AYM during passaging and proliferation reflects and contributes to hESCs and their derived progenitor cells lineage specificity maintenance,through the underlying mechanistic pathways of stiffness-induced cytoskeletal organization and the downstream YAP signaling.These findings highlighted the potential of AYM as an indicator to select suitable substrate stiffness for stem cell specificity maintenance during in vitro expansion for regenerative applications.展开更多
A convenient technique is reported in this note for measuring elastic modulus of extremely soft material for cellular adhesion. Specimens of bending cylinder under gravity are used to avoid contact problem between tes...A convenient technique is reported in this note for measuring elastic modulus of extremely soft material for cellular adhesion. Specimens of bending cylinder under gravity are used to avoid contact problem between testing device and sample, and a beam model is presented for evaluating the curvatures of gel beams with large elastic deformation. A self-adaptive algorithm is also proposed to search for the best estimation of gels＇ elastic moduli by comparing the experimental bending curvatures with those computed from the beam model with preestimated moduli. Application to the measurement of the property of polyacrylamide gels indi- cates that the material compliance varies with the concentrations of bis-acrylamide, and the gels become softer after being immersed in a culture medium for a period of time, no matter to what extent they are polymerized.展开更多
It has been a known fact in classical mechanics of materials that Young’s modulus is an indicator of material stiffness and materials with a higher Young’s modulus are stiffer. At the nanoscale, within the scope and...It has been a known fact in classical mechanics of materials that Young’s modulus is an indicator of material stiffness and materials with a higher Young’s modulus are stiffer. At the nanoscale, within the scope and under specific circumstances described in this paper, however, a nanorod (or a nanotube) with a smaller Young’s modulus (smaller stress-strain rate) is stiffer. In such a scenario, Young’s modulus is not a stiffness indicator for nanostructures. Furthermore, the nonlocal stress-strain rate is dependent on types of load, boundary conditions and location. This is likely to be one of the many possible reasons why numerous experiments in the past obtained significantly varying values of Young’s modulus for a seemingly identical nanotube, i.e. because the types of loading and/or boundary conditions in the experiments were different, as well as at which point the property was measured. Based on the nonlocal elasticity theory and within the scope of material and geometric linearity, this paper reports the strange and hitherto unrealized effect that a nanorod (or a nanotube) with a lower Young’s modulus (smaller stress-strain rate) indicates smaller extension in tensile analysis. Similarly, it is also predicted that a nanorod (or a nanotube) with a lower Young’s modulus results in smaller bending deflection, higher critical buckling load, higher free vibration frequency and higher wave propagation velocity, which are at all consequences of a stiffer nanostructure.展开更多
In gas turbines, thermal barrier coatings （TBCs） applied by air plasma spraying are widely used to lower the temperature of hot components. To analyze the characteristics of TBCs such as residual stress, bond streng...In gas turbines, thermal barrier coatings （TBCs） applied by air plasma spraying are widely used to lower the temperature of hot components. To analyze the characteristics of TBCs such as residual stress, bond strength, fracture toughness, and crack propagation ratio, the Young＇s modulus and Poisson＇s ratio are important parameters. For TBC is a brittle and thin film, it is desirable to evaluate those properties while the coatings are bonded to a substrate. An atmospheric plasma spray MCrAIY bond coat and Yttria stabilized zirconia （YSZ） top coat are deposited onto a nickel-base superalloy GH150 substrate. The Young＇s modulus and Poisson＇s ratio are measured by cantilever beam bending with NDI. The method will be developed to test the Young＇ s modulus and Poisson ratio of other multilayer systems.展开更多
Young′s Modulus of concrete is studied on the basis of triaxial compressive experiments. The authors proposed two empirical equations to calculate its static Young′s modulus and dynamic Young′s modulus when dynamic...Young′s Modulus of concrete is studied on the basis of triaxial compressive experiments. The authors proposed two empirical equations to calculate its static Young′s modulus and dynamic Young′s modulus when dynamic Poisson ratio μ d varies nearby 0.20.P wave velocity and elastic modulus have the same varying tendency as letter N. μ,μ d decrease with the increase of loading rate and μ d has a great effect on the parameters E d and E D.展开更多
Polymer layers adsorbed to a surface or in a confined environment often change their mechanical properties. There is even the possibility of solidification of the confined layer. To judge the stiffness of such a layer...Polymer layers adsorbed to a surface or in a confined environment often change their mechanical properties. There is even the possibility of solidification of the confined layer. To judge the stiffness of such a layer, we used the Hertz model to calculate the Young＇s modulus of the polymer layer in the confinement of AFM experiments with silicon nitride tip with a radius of curvature ofR ≈ 50 nm and a glass sphere attached to the cantilever R =5 μm. Since there is no visible indentation of the layer in the AFM experiments, the layer is either penetrated very easily, or the indentation is too small to be seen in a force curve. The latter would be the case for a polymer layer with a Young＇s modulus above 4 × 10^8 Pa in case of an experiment with a silicon nitride tip and 4×10^5 Pa in case of a glass sphere.展开更多
The flat cylindrical indentation tests with different sizes of punch radius were investigated using finite element method （FEM） aimed to reveal the effect of punch size on the indentation behavior of the film/substr...The flat cylindrical indentation tests with different sizes of punch radius were investigated using finite element method （FEM） aimed to reveal the effect of punch size on the indentation behavior of the film/substrate system. Based on the FEM results analysis, two methods was proposed to separate film＇s reduced Young＇s modulus from a film/substrate system. The first method was based on a new weight function that quantifies film＇s and substrate＇s contributions to the overall mechanical properties of the film/substrate system in the flat cylindrical indentation test. The second method, a numerical approach, including fitting and extrapolation procedures was put forward. Both of the results from the two methods showed a reasonable agreement with the one input FE model. At last, the effect of maximum indentation depth and the surface micro-roughness of the thin film on the reduced Young＇s modulus of the film/substrate system were discussed. The methods proposed in the present study provide some new conceptions on evaluating other properties of thin films, e.g. creep, for which a flat-ended punch is also employed.展开更多
Based on the Hertzian granular contact mechanics model, the paper built up a Macroscopic Young’s Elastic Modulus of particle/granular packing rock layers, and built up a ties to connecting Young’s Elastic Modulus of...Based on the Hertzian granular contact mechanics model, the paper built up a Macroscopic Young’s Elastic Modulus of particle/granular packing rock layers, and built up a ties to connecting Young’s Elastic Modulus of sand particle in Meso and the Macroscopic Young’s Modulus of granular packing rock layers. The Macroscopic Young’s Modulus of granular packing rock layers is far less than the Young’s Modulus of sand particle. The Macroscopic Young’s Modulus of granular packing rock layers is proportioned to the powers of 1/3 of the vertical contact force of sand particles. The Macroscopic Young’s Modulus is inversely proportional to particle diameter. The paper calculated the vertical contact force of five types aligning mode of the particles. When equal stress, the increased of the coordination number lead to the decrease of the contact force fn, this lead to the coordination number is an inverse proportion to Macroscopic Young’s Modulus. But the larger coordination number change only means very little Macroscopic Young’s Modulus change.展开更多
基金financially supported by the National Key R&D Program of China(No.2021YFB3701203)the National Natural Science Foundation of China(Nos.U22A20113,52201116,52071116,and 52261135543)+1 种基金Heilongjiang Touyan Team ProgramChina Postdoctoral Science Foundation(No.2022M710939).
文摘To enhance the Young’s modulus(E)and strength of titanium alloys,we designed titanium matrix composites with intercon-nected microstructure based on the Hashin-Shtrikman theory.According to the results,the in-situ reaction yielded an interconnected microstructure composed of Ti_(2)C particles when the Ti_(2)C content reached 50vol%.With widths of 10 and 230 nm,the intraparticle Ti lamellae in the prepared composite exhibited a bimodal size distribution due to precipitation and the unreacted Ti phase within the grown Ti_(2)C particles.The composites with interconnected microstructure attained superior properties,including E of 174.3 GPa and ultimate flexural strength of 1014 GPa.Compared with that of pure Ti,the E of the composite was increased by 55% due to the high Ti_(2)C content and interconnected microstructure.The outstanding strength resulted from the strong interfacial bonding,load-bearing capacity of interconnected Ti_(2)C particles,and bimodal intraparticle Ti lamellae,which minimized the average crack driving force.Interrupted flexural tests revealed preferential crack initiation along the{001}cleavage plane and grain boundary of Ti_(2)C in the region with the highest tensile stress.In addition,the propagation can be efficiently inhibited by interparticle Ti grains,which prevented the brittle fracture of the composites.
文摘Like other manufacturing techniques,plasma spraying has also a non-linear behavior because of the contribution of many coating variables.This characteristic results in finding optimal factor combination difficult.Subsequently,the issue can be solved through effective and strategic statistical procedures integrated with systematic experimental data.Plasma spray parameters such as power,stand-off distance and powder feed rate have significant influence on coating characteristics like Young’s modulus.This paper presents the use of statistical techniques in specifically response surface methodology(RSM),analysis of variance,and regression analysis to develop empirical relationship to predict Young’s modulus of plasma-sprayed alumina coatings.The developed empirical relationships can be effectively used to predict Young’s modulus of plasma-sprayed alumina coatings at 95%confidence level.Response graphs and contour plots were constructed to identify the optimum plasma spray parameters to attain maximum Young’s modulus in alumina coatings.A linear regression relationship was established between porosity and Young’s modulus of the alumina coatings.
基金Science Research Foundation of Shanghai Municipal Education Commission (No.06VZ004)
文摘The elastic-plastic indentation properties of materials with varying ratio of hardness to Young’s modulus(H/E) were analyzed with the finite element method. And the indentation stress fields of materials with varying ratio H/E on the surface were studied by the experiment. The results show that the penetration depth, contact radius, plastic pile-up and the degree of elastic recovery depend strongly on the ratio H/E. Moreover, graphs were established to describe the relationship between the elastic-plastic indentation parameters and H/E. The established graphs can be used to predict the H/E of materials when compared with experimental data.
基金financial support from the National Key R&D Program of China (2018YFF0214500)
文摘The Young’s modulus was measured at high temperatures by impulse excitation of vibration method,and the effects of heating rate,holding time and temperature cycle on the test results were analyzed.The results show that the heating rate has obvious effect on the high temperature Young’s modulus of the green body,but has no obvious effect on that of the sintered products;the holding time of the heating process has no regular effect on the Young’s modulus,and the effect varies with the different products at a certain temperature;the method can also be used to test the Young’s modulus during cooling process.
文摘Introduction: To investigate a long-term in vivo deterioration of polymethylmethacrylate (PMMA) bone cement over time, we evaluated retrieved PMMA cement in terms of chemical elements presenting in the cement using energy dispersive analysis of X-rays;Knoop hardness;and the Young’s modulus using scanning acoustic microscopy. Materials and Methods: For mechanical evaluation, we could neglect the influences of entrapped air bubbles or blood by the use of small specimens. The study was based on thirteen cement samples (six used in the acetabulum and seven in the femur) derived from eight patients (age at revision surgery: mean 72.5, range 68 to 79). All of these samples were Simplex-P?cement. They were functioning well at least ten years after the previous surgery. Duration until revision surgery was ranged 12 to 25 years (average, 17.4 years). The reason for revision was aseptic mechanical loosening. Twenty samples of Simplex-Preg;cement were served by manually mixing as a control. Results: The average of the hardness of the cement was 17.0 ± 1.2 (range, 13.4-20.6). In the control, the hardness was 17.8 ± 1.5 (range, 14.0-24.6). There was no significant difference between these values. The mean of Young’s modulus of the cement was 5.61 ± 0.19 GPa (range, 5.09-6.10). In the control, the modulus was 6.04 ± 0.13 GPa (range, 5.68-6.45). Although the modulus was significantly less than that of the control, there was only 7% decrease in average between twelve and twenty-five years in vivo. Conclusions: Our results suggest that long-term implantation and functional loading in vivo may not be the limiting factor in the mechanical integrity of the bone cement.
文摘In this paper, we will study the most important effects in the nano-scale resonator: the coupling effect of temperature and strain rate, and the non-Fourier effect in heat conduction. A solution for the generalized thermoelastic vibration of nano-resonator induced by thermal loading has been developed. The Young’s modulus is taken as a linear function of the reference temperature. The effects of the thermal loading and the reference temperature in all the studied fields have been studied and represented in graphs with some comparisons. The Young’s modulus makes significant effects on all the studied fields where the values of the temperature, the vibration of the deflection, stress, displacement, strain, stress-strain energy increase when the Young’s modulus has taken to be variable.
基金This work is financially supported by the National Natural Science Foundation of China(No.52073030).
文摘For decades,it has been well accepted that every 1 wt.%Li addition to Al will reduce Al alloy’s density by 3%and increase its Young’s modulus by 6%.However,the fundamental mechanism of modulus improve-ments stays controversial though all studies agreed that the contribution of such a substantial boosting comes from Li-rich clusters either in solid solution or precipitations.In this study,we experimentally produce nano-sized Li-rich clusters by non-equilibrium solidification using centrifugal casting and trace their evolutions as a function of subsequent heat treatments.High-resolution transmission electron mi-croscopy(HRTEM)reveals a further decrease in the lattice constants of Li-rich regions from the as-cast(0.406 nm),solid solution(0.405 nm)to the aged state(0.401 nm),while Young’s modulus of the Al-Li al-loy reaches 89.16 GPa.Small-angle neutron scattering(SANS)experiments and first-principle calculations based on density functional theory have shown both the bond strength around precipitates and the size of those Li-rich region dominate Young’s modulus.At the beginning,it is volumetric compression due to Li addition that increases modulus,tightening the Al-Al potential curves.In the end,it is the Al-Al and Al-Li valence bonds in Al 3 Li at large size and high-volume fraction which increase its second derivative of internal energy and thus Young’s modulus.
基金financially supported by the National Natural Science Foundation of China(No.51871077)the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515012626)+3 种基金the Shenzhen Knowledge Innovation Plan-Fundamental Re-search(Discipline Distribution)(No.JCYJ20180507184623297)the S henzhen Science and Technology Plan-Technology Innovation(No.KQJSCX20180328165656256)the Development and Reform Commission of Shenzhen Municipality-Shenzhen R&D Center for Al-based Hydrogen Hydrolysis Materials(No.ZX20190229)the Startup Foundation from Shenzhen and Startup Foundation from Harbin Institute of Technology(Shenzhen).
文摘Stress shielding is caused by the mismatch of stiffness between bone and implant materials,which may give rise to bone resorption and loosening,thereby causing implantation failure.There is a huge gap between Young’s modulus of human bone and low Young’s modulusβTi alloys.A porous structure design can achieve the target of low Young’s modulus,and thus achieve the matching between human bone and implant materials.However,a suitable space holder(SH)that can be applied at high temperatures and sintering pressure has not been reported.In this study,the TiZrNbTa/Ti titanium matrix composite(TMC)with high strength and large ductility was used as scaffold materials and combined the SH technique with the spark plasma sintering(SPS)technique to obtain a porous structure.A novel space holder,i.e.,MgO particles was adopted,which can withstand high-temperature sintering accompanied by a sintering pressure.The porous TiZrNbTa/Ti with 40 vol.%MgO added exhibits a maximum strength of 345.9±10.4 MPa and Young’s modulus of 24.72±0.20 GPa,respectively.It possesses higher strength compared with human bone and matches Young’s modulus of human bone,which exhibits great potential for clinical application.
文摘To get the quantitive value of abnormal biological tissues, an inverse algorithm about the Young＇s modulus based on the boundary extraction and the image registration technologies is proposed. With the known displacements of boundary tissues and the force distribution, the Young＇s modulus is calculated by constructing the unit system and the inverse finite element method （IFEM）. Then a tough range of the modulus for the whole tissue is estimated referring the value obtained before. The improved particle swarm optimizer （PSO） method is adopted to calculate the whole Yong＇s modulus distribution. The presented algorithm overcomes some limitations in other Young＇s modulus reconstruction methods and relaxes the displacements and force boundary condition requirements. The repetitious numerical simulation shows that errors in boundary displacement are not very sensitive to the estimation of next process; a final feasible solution is obtained by the improved PSO method which is close to the theoretical values obtained during searching in an extensive range.
基金financially supported by the National Key Research and Development Program of China(No.2019YFA0708700)National Natural Science Foundation of China(52174054,51804326)Shandong Provincial Natural Science Foundation(ZR2019BEE046)
文摘The effect of mechanical strength of the dispersed particle gel(DPG)on its macro plugging performance is significant,however,little study has been reported.In this paper,DPG particles with different mechanical strengths were obtained by mechanical shearing of bulk gels prepared with different formula.Young’s moduli of DPG particles on the micro and nano scales were measured by atomic force microscope for the first time.The mapping relationship among the formula of bulk gel,the Young’s moduli of the DPG particles and the final plugging performance were established.The results showed that when the Young’s moduli of the DPG particles increased from 82 to 328 Pa,the plugging rate increased significantly from 91.46%to 97.10%due to the distinctly enhanced stacking density and strength at this range.While when the Young’s moduli of the DPG particles surpassed 328 Pa,the further increase of plugging rate with the Young’s moduli of the DPG particles became insignificant.These results indicated that the improvement of plugging rate was more efficient by adjusting the Young’s moduli of the DPG particles within certain ranges,providing guidance for improving the macroscopic application properties of DPG systems in reservoir heterogeneity regulation.
文摘Young’s modulus of New Red Sandstone was investigated experimentally to gain insight into its nonlinear nature.A large experimental programme was carried out by applying a controllable quasi-static and dynamic uniaxial loading to 286 dry sandstone samples of four different sizes.The static and dynamic tests,similar to those aiming at determining the uniaxial compressive strength,were conducted using the state-of-the-art experimental facilities at the University of Aberdeen including a custom-built small experimental rig for inducing a dynamic uniaxial compressive load via a piezoelectric transducer.The obtained results have confirmed a complex nature of Young’s modulus of sandstone.Specifically,under a harmonic dynamic loading,it shows strongly nonlinear behaviour,which is hardening and softening with respect to frequency and amplitude of the dynamic loading,respectively.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50801005)
文摘It is difficult to establish structure-property relationships in a defective solid because of its inhomogeneous-geometry microstructure caused by defects. In the present research, the effects of pores and cracks on the Young’s modulus of a defective solid are studied. Based on the law of the conservation of energy, mathematical formulations are proposed to indicate how the shape, size, and distribution of defects affect the effective Young’s modulus. In this approach, detailed equations are illustrated to represent the shape and size of defects on the effective Young’s modulus. Different from the results obtained from the traditional empirical analyses, mixture law or statistical method, for the first time, our results from the finite element method （FEM） and strict analytical calculation show that the influence of pore radius and crack length on the effective Young’s modulus can be quantified. It is found that the longest crack in a typical microstructure of ceramic coating dominates the contribution of the effective Young’s modulus in the vertical direction of the crack.
基金This work was financially supported by the Beijing Municipal Science&Technology Commission(Z181100001818005)the National Natural Science Foundation of China(31671036)and Beijing Natural Science Foundation(JQ18022)the Australian National Health and Medical Research Council(APP1120249).
文摘Background:Apparent Young’s modulus(AYM),which reflects the fundamental mechanical property of live cells measured by atomic force microscopy and is determined by substrate stiffness regulated cytoskeletal organization,has been investigated as potential indicators of cell fate in specific cell types.However,applying biophysical cues,such as modulating the substrate stiffness,to regulate AYM and thereby reflect and/or control stem cell lineage specificity for downstream applications,remains a primary challenge during in vitro stem cell expansion.Moreover,substrate stiffness could modulate cell heterogeneity in the single-cell stage and contribute to cell fate regulation,yet the indicative link between AYM and cell fate determination during in vitro dynamic cell expansion(from single-cell stage to multi-cell stage)has not been established.Results:Here,we show that the AYM of cells changed dynamically during passaging and proliferation on substrates with different stiffness.Moreover,the same change in substrate stiffness caused different patterns of AYM change in epithelial and mesenchymal cell types.Embryonic stem cells and their derived progenitor cells exhibited distinguishing AYM changes in response to different substrate stiffness that had significant effects on their maintenance of pluripotency and/or lineage-specific characteristics.On substrates that were too rigid or too soft,fluctuations in AYM occurred during cell passaging and proliferation that led to a loss in lineage specificity.On a substrate with‘optimal’stiffness(i.e.,3.5 kPa),the AYM was maintained at a constant level that was consistent with the parental cells during passaging and proliferation and led to preservation of lineage specificity.The effects of substrate stiffness on AYM and downstream cell fate were correlated with intracellular cytoskeletal organization and nuclear/cytoplasmic localization of YAP.Conclusions:In summary,this study suggests that optimal substrate stiffness regulated consistent AYM during passaging and proliferation reflects and contributes to hESCs and their derived progenitor cells lineage specificity maintenance,through the underlying mechanistic pathways of stiffness-induced cytoskeletal organization and the downstream YAP signaling.These findings highlighted the potential of AYM as an indicator to select suitable substrate stiffness for stem cell specificity maintenance during in vitro expansion for regenerative applications.
基金supported by the National Basic Research Program (2007CB935602)the National Natural Science Foundation of China (90607004, 10672005)
文摘A convenient technique is reported in this note for measuring elastic modulus of extremely soft material for cellular adhesion. Specimens of bending cylinder under gravity are used to avoid contact problem between testing device and sample, and a beam model is presented for evaluating the curvatures of gel beams with large elastic deformation. A self-adaptive algorithm is also proposed to search for the best estimation of gels＇ elastic moduli by comparing the experimental bending curvatures with those computed from the beam model with preestimated moduli. Application to the measurement of the property of polyacrylamide gels indi- cates that the material compliance varies with the concentrations of bis-acrylamide, and the gels become softer after being immersed in a culture medium for a period of time, no matter to what extent they are polymerized.
基金supported by the Research Grants Council of the HongKong Special Administrative Region (Grant No. CityU 117406)
文摘It has been a known fact in classical mechanics of materials that Young’s modulus is an indicator of material stiffness and materials with a higher Young’s modulus are stiffer. At the nanoscale, within the scope and under specific circumstances described in this paper, however, a nanorod (or a nanotube) with a smaller Young’s modulus (smaller stress-strain rate) is stiffer. In such a scenario, Young’s modulus is not a stiffness indicator for nanostructures. Furthermore, the nonlocal stress-strain rate is dependent on types of load, boundary conditions and location. This is likely to be one of the many possible reasons why numerous experiments in the past obtained significantly varying values of Young’s modulus for a seemingly identical nanotube, i.e. because the types of loading and/or boundary conditions in the experiments were different, as well as at which point the property was measured. Based on the nonlocal elasticity theory and within the scope of material and geometric linearity, this paper reports the strange and hitherto unrealized effect that a nanorod (or a nanotube) with a lower Young’s modulus (smaller stress-strain rate) indicates smaller extension in tensile analysis. Similarly, it is also predicted that a nanorod (or a nanotube) with a lower Young’s modulus results in smaller bending deflection, higher critical buckling load, higher free vibration frequency and higher wave propagation velocity, which are at all consequences of a stiffer nanostructure.
文摘In gas turbines, thermal barrier coatings （TBCs） applied by air plasma spraying are widely used to lower the temperature of hot components. To analyze the characteristics of TBCs such as residual stress, bond strength, fracture toughness, and crack propagation ratio, the Young＇s modulus and Poisson＇s ratio are important parameters. For TBC is a brittle and thin film, it is desirable to evaluate those properties while the coatings are bonded to a substrate. An atmospheric plasma spray MCrAIY bond coat and Yttria stabilized zirconia （YSZ） top coat are deposited onto a nickel-base superalloy GH150 substrate. The Young＇s modulus and Poisson＇s ratio are measured by cantilever beam bending with NDI. The method will be developed to test the Young＇ s modulus and Poisson ratio of other multilayer systems.
文摘Young′s Modulus of concrete is studied on the basis of triaxial compressive experiments. The authors proposed two empirical equations to calculate its static Young′s modulus and dynamic Young′s modulus when dynamic Poisson ratio μ d varies nearby 0.20.P wave velocity and elastic modulus have the same varying tendency as letter N. μ,μ d decrease with the increase of loading rate and μ d has a great effect on the parameters E d and E D.
文摘Polymer layers adsorbed to a surface or in a confined environment often change their mechanical properties. There is even the possibility of solidification of the confined layer. To judge the stiffness of such a layer, we used the Hertz model to calculate the Young＇s modulus of the polymer layer in the confinement of AFM experiments with silicon nitride tip with a radius of curvature ofR ≈ 50 nm and a glass sphere attached to the cantilever R =5 μm. Since there is no visible indentation of the layer in the AFM experiments, the layer is either penetrated very easily, or the indentation is too small to be seen in a force curve. The latter would be the case for a polymer layer with a Young＇s modulus above 4 × 10^8 Pa in case of an experiment with a silicon nitride tip and 4×10^5 Pa in case of a glass sphere.
基金supports from National Natural Science Foundation of China (Nos.50775183 and 50805118)Research Fund for Doctoral Programof higher Education (N6CJ0001)National High Technical Research and Development Programme of China (No.2009AA04Z418)
文摘The flat cylindrical indentation tests with different sizes of punch radius were investigated using finite element method （FEM） aimed to reveal the effect of punch size on the indentation behavior of the film/substrate system. Based on the FEM results analysis, two methods was proposed to separate film＇s reduced Young＇s modulus from a film/substrate system. The first method was based on a new weight function that quantifies film＇s and substrate＇s contributions to the overall mechanical properties of the film/substrate system in the flat cylindrical indentation test. The second method, a numerical approach, including fitting and extrapolation procedures was put forward. Both of the results from the two methods showed a reasonable agreement with the one input FE model. At last, the effect of maximum indentation depth and the surface micro-roughness of the thin film on the reduced Young＇s modulus of the film/substrate system were discussed. The methods proposed in the present study provide some new conceptions on evaluating other properties of thin films, e.g. creep, for which a flat-ended punch is also employed.
文摘Based on the Hertzian granular contact mechanics model, the paper built up a Macroscopic Young’s Elastic Modulus of particle/granular packing rock layers, and built up a ties to connecting Young’s Elastic Modulus of sand particle in Meso and the Macroscopic Young’s Modulus of granular packing rock layers. The Macroscopic Young’s Modulus of granular packing rock layers is far less than the Young’s Modulus of sand particle. The Macroscopic Young’s Modulus of granular packing rock layers is proportioned to the powers of 1/3 of the vertical contact force of sand particles. The Macroscopic Young’s Modulus is inversely proportional to particle diameter. The paper calculated the vertical contact force of five types aligning mode of the particles. When equal stress, the increased of the coordination number lead to the decrease of the contact force fn, this lead to the coordination number is an inverse proportion to Macroscopic Young’s Modulus. But the larger coordination number change only means very little Macroscopic Young’s Modulus change.
