用有限元法计算飞秒激光双光子成型点弹性模量

采用有限元法对材料为SCR500的飞秒激光双光子成型点力学性能进行建模及仿真计算，得出了不同弹性模量下成型点与探针之间的作用力．进而利用原子力显微镜接触模式，选用无针尖探针，测量了成型点的力学性能，得出了相同位移载荷下成型点与探针之间的作用力．将测量结果和仿真结果进行比较，推算出成型点的弹性模量．分析结果表明。双光子固化成型点的弹性模量大约为宏观材料弹性模量的1／7．这为进一步研究双光子飞秒激光加工微器件的力学性能提供了基础．     

弯曲型支撑-框架的假想荷载法

为避免在钢结构设计中逐一去确定框架柱的计算长度,该文提出了一种应用于弯曲型支撑框架的假想荷载法。将假想荷载作用于框架楼层,配合二阶弹性分析,考虑材料非线性、残余应力和初始几何缺陷,研究了多种几何和荷载条件下的弯曲型支撑框架模型,分析了一系列模型的极限承载力,提出了统一的假想荷载系数以及假想荷载的近似公式,无论是有水平荷载或无水平荷载,无论是等截面还是变截面,其结果与有限元结果都符合较好。     

有限元模拟对CdZnTe共面栅探测器的优化设计

利用有限元分析软件ANSYS,通过变化栅宽、沟宽及栅极位置等因素,模拟了共面栅探测器在不同的电极设计时的电势分布,并讨论了电极分布不对称时所产生的边缘对感应信号的影响,显示了具有优化设计的共面栅电极,可以进一步提高探测器的能量分辩率。     

Numerical computation of thermal fatigue crack growth of cast iron

Thermal fatigue experiments have been carried out on a single‐edge wedge specimen of the SiMo cast iron to reproduce the conditions experienced by exhaust manifolds during operation. The leading edge temperature was cycled between 20 and 750 °C and the temperature distribution on the specimen surface was measured by thermocouples throughout the thermal cycle. Due to the complexity of the loading and interaction effects between cracks, numerical simulation of crack propagation and shielding effects in multicracked structures appear a useful way to analyze this problem. Therefore, 3D thermo‐mechanical computation was performed with the finite element code ABAQUS of both un‐cracked and multicracked specimen. This computation allowed us to assess the temperature, stresses and strains distribution over a thermal fatigue specimen and the estimation of the crack growth rate using the energy criteria based on the calculation of the J‐integral crack tip.     

悬臂梁压电发电装置的实验研究

为了进行压电陶瓷材料发电性能测试与研究,研制了一套悬臂梁压电振子发电系统.设计了悬臂梁压电振子,并对压电振子进行了有限元分析和电导测试.在此基础上,设计了能量存储电路,并在低频下对悬臂梁压电振子发电性能进行了实验研究.研究结果表明,当悬臂梁压电振子处于谐振频率状态下振动时,输出电压和功率达到最大.输出电压随着负载的增大而增大,输出功率并不随着负载的增大而增大;压电振子存在-个最佳阻抗,当负载与最佳阻抗匹配时,此时压电振子的能量转化效率最高且输出功率最大.利用本实验系统进行压电发电实验测试,当负载为50 kΩ时,压电振子输出电压为7 V;当负载电阻为15 kΩ时,此时的输出功率最大可达到1.4 mW,产生的功率可以满足无线传感器等低耗能产品的供能需求.     

2300轧机上支承辊轴座强度分析

论述了在ＡＧC改造中上支承辊承座的改造,利用有限单元进行强度校核,并提出最优结果。     

稳态扩展裂纹前缘形态的研究

利用超声波断口图技术对不同类型的带单侧贯穿裂纹的PMMA试件进行了测试,得到试件断口上的超声波线。基于ANSYS软件的有限元分析,计算了试件的三维J积分,得到的试件在不同裂纹长度下的三维J积分与它们断口图上的超声波线的形状和凸凹方向相似,将试件扩展裂纹前缘由直线调整为特定曲线后,计算出的三维J积分趋向常量,证实了扩展裂纹前缘的任一点,J积分矢量的幅值都是相同常量的假设。     

条烟配送笼车的结构强度分析与轻量化设计

采用ADAMS分析软件对条烟配送笼车在主副笼叠加运输方式中的载荷进行了分析,得到主笼车在设定条件下的最大载荷值。在此基础上,利用有限元分析软件对主笼车进行应力和形变计算,结果表明,现有的笼车强度和刚度均有较大的设计裕量,可对其进行轻量化设计。按照方管设计的国家标准,通过减薄钢管壁厚进行了减量化设计,并对其进行了应力和形变分析。对比分析结果可知,对笼车开展的轻量化设计,不仅可以满足现有条烟配送运输要求,同时节约了笼车的制造成本,减轻了配送运输过程中的空载质量,有效地提高了运输效能,减小了运输能耗。     

A simplified micromechanical model for predicting effective mechanical behaviors of continuous bidirectional-fiber-reinforced composites

A simplified micromechanical model is proposed to estimate the macroscopic mechanical properties of continuous bidirectional-fiber-reinforced composites (CBFRCs) by ignoring Poisson's effect. The model is validated by results from a homogenized finite element approach. Based on the proposed analytical model, the influences of the ratios of fiber/matrix modulus and the fiber volume ratio on the effective modulus and the tensile strength are specifically investigated. The suggested theoretical method provides a convenient tool for estimating the effective mechanical behaviors of CBFRCs, which can be expressed as a function of fiber volume fraction and material parameters.     

3D J‐integral evaluation using the computation of line and surface integrals

In the analysis of fracture mechanics of structures using three‐dimensional (3D) J‐integral, an integral evaluation of line and surface is required. However, because surface integral evaluation requires the calculation of the second derivative of displacement field and commercial finite element codes cannot calculate it, then this portion of the integral is neglected in some research. In this paper, a method for computing 3D J‐integral is presented using finite element analysis. In the analysis, the second derivative evaluation of displacement field is employed. The method is implemented in calculating the J‐integral of some 3D cracks and results are compared to well‐known reference values. The results show that the method is reliable and is suitable for applications in engineering. The portion of 3D J‐integral, namely the surface integral value is investigated and it is shown that neglecting this portion can introduce considerable error in the final results.     

三维五向编织复合材料的力学性能分析Ⅱ:细观应力数值模拟

在实验观察的基础上, 考虑轴纱的挤压变形及纱线填充因子变化, 修正了现有的细观结构模型, 建立了更加真实反映三维五向编织复合材料内部编织结构的单胞模型。利用该模型采用3D 有限元法计算了材料的轴向弹性模量, 数值预测与实验数据吻合较好。分析了单胞在拉伸载荷作用下的细观应力分布, 为材料进一步的强度预测奠定了基础。      

Fracture behaviour of cracked carbon nanotube‐based polymer composites: Experiments and finite element simulations

This paper studies the fracture behaviour of cracked carbon nanotube (CNT)‐based polymer composites by a combined numerical–experimental approach. Tensile tests were conducted on single‐edge cracked plate specimens of CNT/polycarbonate composites at room temperature and liquid nitrogen temperature (77 K), and the critical loads for fracture instabilities were determined. Elastic–plastic finite element simulations of the tests were then performed to evaluate the J‐integrals corresponding to the experimentally determined critical loads. Scanning electron microscopy examinations were also made on the specimen fracture surfaces, and the fracture mechanisms of the CNT‐based composites were discussed.