摘要：Based on the nonlocal strain gradient theory(NSGT),the static bending behaviors of an axially functionally graded(AFG)Bernoulli-Euler microbeam subjected to concentrated and distributed loads are *** material property of the AFG microbeam changes continuously along the longitudinal *** the basis of the minimum potential energy principle,the equations of motion and associated classical and non-classical boundary conditions are ***,Galerkin’s weighted residual method in conjunction with the normalization technique are utilized to solve the governing differential *** transverse deformations of the AFG microbeam suffering the sinusoidal distributed load within the framework of NSGT,nonlocal elasticity theory(NET),strain gradient theory(SGT)and classical elasticity theory(CET)are *** is observed that the bending flexibility of the microbeam decreases with the increase in the ratio of the material length scale parameter to the beam ***,the bending flexibility increases with the increase in the material nonlocal *** functionally graded parameter plays an important role in controlling the transverse *** study provides a theoretical basis and a technical reference for the design and analysis of AFG micro-beams in the related regions.

摘要：This paper focuses on the thermo-mechanical behaviors of functionally graded(FG)shape memory alloy(SMA)composite beams based on Timoshenko beam *** volume fraction of SMA fiber is graded in the thickness of beam according to a power-law function and the equivalent parameters are *** governing differential equations,which can be solved by direct integration,are established by employing the composite laminated plate *** influences of FG parameter,ambient temperature and SMA fiber laying angle on the thermo-mechanical behaviors are numerically simulated and discussed under different boundary *** indicate that the neutral plane does not coincide with the middle plane of the composite beam and the distribution of martensite is asymmetric along the *** the increments of the functionally graded parameter and ambient temperature make the composite beam become ***,the influence of the SMA fiber laying angle can be *** work can provide the theoretical basis for the design and application of FG SMA structures.

摘要：研究目的:提出一种新的腐蚀疲劳损伤演化模型,建立基于损伤演化的腐蚀疲劳寿命预测模型。创新要点:将应力腐蚀损伤与疲劳损伤非线性耦合,建立腐蚀疲劳损伤演化律,依托实验确定腐蚀疲劳损伤演化参数,形成基于损伤演化律的腐蚀疲劳寿命预测模型。研究方法:采用理论研究与实验验证相结合的研究方法。选取特定材料设计应力腐蚀实验,回归应力腐蚀门槛值应力和损伤参数(图2);查阅疲劳实验数据建立变幅疲劳损伤模型,将应力腐蚀损伤与变幅疲劳损伤非线性累加形成腐蚀疲劳损伤非线性演化模型。根据腐蚀疲劳实验结果,验证腐蚀疲劳损伤演化模型并确定非线性损伤累加参数(图5和6),形成基于损伤演化律的腐蚀疲劳寿命预测模型。重要结论:从损伤力学角度,将材料的腐蚀疲劳损伤处理成应力腐蚀损伤与疲劳损伤的非线性累加,形成腐蚀疲劳损伤演化模型。结合LY12CZ铝合金的试验结果,验证了损伤演化模型的可行性。该方法可以为材料腐蚀疲劳的寿命评价研究提供新的思路。