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通过对5个野双峰驼（Camelus bactrianus ferus）下颌骨进行螺旋CT扫描，利用软件Amira 311对CT扫描图三维重建得到下颌骨三维点云图，并利用Geomagic软件进行实体化，通过有限元分析软件Ansys 140对野双峰驼下颌骨角部施加1000 N大小的力后对下颌骨进行有限元分析，得到下颌骨在受力时的应力分布情况：当左下颌角受到水平向右垂直于矢状面的外力时，左下颌角及髁状突颈部极易造成骨折，左颏孔区可能会出现骨裂，而其余部分仅会造成轻微损伤。当右下颌角下缘受到垂直向上垂直于矢状面的外力时，也易出现同样的结果。由此得出结论：当野双峰驼下颌骨角部受到瞬间外力时，应力主要集中在施加力所在骨支的薄弱区域，应力较大部位与骨折易发部位密切相关；且在薄弱区域，下颌角及髁状突颈部的损害最为严重。以上结果有利于深入了解野双峰驼下颌骨应力分布情况，并为骨三维重建在生物学领域的应用提供理论依据。

目的：研究正常功能负荷下，骨结合率对骨界面应力分布的影响。方法：采用三维有限元法分析比较骨结合率分别为100%、75%、50%和25%时，骨界面应力分布状况及种植体位移。结果：随骨结合率升高，骨界面平均应力降低，最大应力值减小，种植体颈周密质骨应力集中程度降低，稳定性增强。结论：从生物力学观点看，骨结合率大于50%的种植体-骨界面更为安全，适宜的种植体-骨界面的结合率不应低于50%。

目的 分析下颌桩核基牙式全口覆盖义齿基托及其支持组织的应力分布状况，为临床工作提供实验依据和指导。方法 应用三维有限元法研究下颌桩核基牙式全口覆盖义齿基托及支持组织的应力分布特点，计算基托、黏膜、皮质骨的应力值并与自然基牙作对比分析。结果 基托在基牙周围有明显应力集中；双侧磨牙区牙槽嵴顶处的黏膜应力值相对较大；皮质骨主要承受压应力，在基牙周围有明显应力集中。结论 基托在基牙处易折裂；基牙周围皮质骨受力较大，易发生骨吸收；桩核对义齿基托及黏膜的应力分布无明显影响，对皮质骨的应力分布有一定影响。

On 25 April 2015,an M_w 7.8 earthquake occurred on the Main Himalaya Thrust fault with a dip angle of~7° about77 km northwest of Kathmandu,Nepal.This Nepal Gorkha event is the largest one on the Himalayan thrust belt since 1950.Here we use the compressive sensing method in the frequency domain to track the seismic radiation and rupture process of this event using teleseismic P waves recorded by array stations in North America.We also compute the distribution of static shear stress changes on the fault plane from a coseismic slip model.Our results indicate a dominant east-southeastward unilateral rupture process from the epicenter with an average rupture speed of ~3 km s~（-1）.Coseismic radiation of this earthquake shows clear frequency-dependent features.The lower frequency（0.05-0.3 Hz） radiation mainly originates from large coseismic slip regions with negative coseismic shear stress changes.In comparison,higher frequency（0.3-0.6 Hz） radiation appears to be from the down-dip part around the margin of large slip areas,which has been loaded and presents positive coseismic shear stress changes.We propose an asperity model to interpret this Nepal earthquake sequence and compare the frequency-dependent coseismic radiation with that in subduction zones.Such frequency-dependent radiation indicates the depth-varying frictional properties on the plate interface of the Nepal section in the main Himalaya thrust system,similar to previous findings in oceanic subduction zones.Our findings provide further evidence of the spatial correlation between changes of static stress status on the fault plane and the observed frequency-dependent coseismic radiation during large earthquakes.Our results show that the frequency-dependent coseismic radiation is not only found for megathrust earthquakes in the oceanic subduction environment,but also holds true for thrust events in the continental collision zone.

Thermal barrier coating （TBC） systems are widely used in industrial gas-turbine engines. However, premature failures have impaired the use of TBCs and cut down their lifetime, which requires a better understanding of their failure mechanisms. In the present study, experimental studies of isothermal cycling are firstly carried out with the observation and estimation of micro- structures. According to the experimental results, a finite element model is established for the analysis of stress perpendicular to the TBC/BC interface. Detailed residual stress distributions in TBC are obtained to reflect the influence of mechanical prop- erties, oxidation, and interfacial roughness. The calculated results show that the maximum tensile stress concentration appears at the peak of TBC and continues to increase with thermal cycles. Because of the microstructural characteristics of plas- ma-sprayed TBCs, cracks initialize in tensile stress concentration （TSC） regions at the peaks of TBC and propagate along the TBC/BC interface resulting in the spallation of TBC. Also, the inclusion of creep is crucial to failure prediction and is more important than the inclusion of sintering in the simulation.

The evolution of misfit dislocation network at γ/γ＇ phase interfaces and the stress distribution characteristics of Ni-based single-crystal superalloys under different temperatures of 0, 100 and 300 K are studied by molecular dynamics （MD） simulation. It was found that a closed three-dimensional misfit dislocation network appears on the γ/γ＇ phase interfaces, and the shape of the dislocation network is independent of the lattice mismatch. Under the influence of the temperature, the dislocation network gradually becomes irregular, a/2 [110] dislocations in the γ matrix phase emit and partly cut into the γ＇ phase with the increase in temperature. The dislocation evolution is related to the local stress field, a peak stress occurs at γ/γ＇ phase interface, and with the increase in temperature and relaxation times, the stress in the γ phase gradually increases, the number of dislocations in the γ phase increases and cuts into γ＇ phase from the interfaces where dislocation network is damaged. The results provide important information for understanding the temperature dependence of the dislocation evolution and mechanical properties of Ni-based single-crystal superalloys.

Effect of Laves phase formation on mechanical properties in a pressurized T-junction of P91 steel pipe at849 K for 58,000 h with 25.65 MPa vapor pressure was studied. Thermodynamic calculations had been performed by using the software Thermo-Calc to study the phase at equilibrium state. Counter plot of von Mises stress in the pipe during service life was calculated by finite element analysis to study the effect of the operated stress distribution on the evolution of Laves phase. The change in the microstructure and mechanical properties in the sites with different stress was also studied. The results indicated that the formation of Laves phase in P91 steel was a thermodynamically possible process due to enrichment of Mo and depletion of C adjacent to M23C6 particles or along martensite lath and packet boundaries. The formation of Laves phase had a detrimental influence on the mechanical properties in P91 steel. The mean size of Laves phase would be significantly increased with increasing operated stress, leading to a reduction in tensile properties and impact energy. In particular, crack initiation energy and crack growth energy during impact test rapidly decreased with increasing the mean size and volume fraction of Laves phase.

In a strip winding process,the sleeve is a hollow cylinder that is mounted between a strip coil and a mandrel to maintain uniform coil shape when the strip coil is very thin,but its deformation behavior has not been investigated before.Thus,a finite element（FE）model was presented to calculate the stress distribution in a sleeve and strip coil when 1-3mm-thick stainless steel was wound around the sleeve.The FE model was developed by extending aprevious model by adding a sleeve between the mandrel and strip,and by modifying the boundary and interaction conditions.The strip winding process was divided into an initial process and a steady-state process.During the initial process,the minimum and maximum pressure required on the belt wrapper to maintain coil shape by self-friction of the strip was calculated by the FE model when the belt wrapper is ejected at the end of the initial process.After the initial process,an analytical model of the steady-state process was established to calculate the stress distribution and was compared with the FE model to validate it.The suggested analytical model took 11 sto give the same stress distribution that the FE model took 30 dto produce.

This paper is to study the two-dimensional stress distribution of a finite functionally graded material （FGM） plate with a circu- lar hole under arbitrary constant loads. Using the method of piece-wise homogeneous layers, the stress analysis of the finite FGM plate having radial arbitrary elastic properties is made based on the complex variable method combined with the least square boundary collocation technique. Numerical results of stress distribution around the hole are then presented for different loading conditions, different material properties and different plate sizes, respectively. It is shown that the stress concentration in the finite plate is generally enhanced compared with the case of an infinite plate, but it can be significantly reduced by choosing proper change ways of the radial elastic modulus.

The residual stress distribution was studied by an analytical model, due to shot peening on the welding carbon steel surface layer. The initial welding residual stresses before shot peening were taken into consideration in this analytical model. The Hertzian elastic contact theory was used to get the elastic compression stress state after impact on the surface layer. The initial welding stress field and the shot peening stress field would superpose and the welding surface layer would yield based on the elastic-plastic evaluation, then the residual stress after shot peening can be achieved. The influence of initial welding residual stress on the stress distribution after shot peening was analyzed and discussed. A series of experiments were carried out and the residual stress on the welding surface was determined by X-ray diffractometer before and after shot peening. The calculation results of the analytical model are consistent with the experimental results. The critical shot velocities when welding surface layer yielded and reverse yielded were calculated. While the welded joint surface material reversely yielded, the maximum compressive residual stress would not obviously increase with the increase of shot velocity, the thickness of the compressive stress layer would be increased. Welding residual tensile stress can enlarge the thickness of the compressive stress layer at the same shot velocity when reverse yield appeared.