Simulation of the bone healing process of fractured long bones applied with a composite bone plate with consideration of the blood vessel growth

The healing process of long bones such as the tibia was simulated on the basis of a mechanoregulation theory by taking blood vessel growth into consideration. The tissue differentiation process of calluses by taking into consideration blood vessel growth was simulated by a user subroutine program based on the mechanoregulation model and a diffusion equation. Composite bone plates made of a plain weave carbon/epoxy composite (WSN3k) and a plain weave glass/polypropylene composite (Twintex) were applied to the fracture site to investigate the effect of plate modulus on the healing performance. The simulation results revealed that the flexible composite bone plate made of Twintex [0]₁₈, which had a slightly higher Young’s modulus than a cortical bone, provided the highest healing performance. Moreover, it was found that the effect of the plate modulus on the healing performance reduced when the blood vessel growth at the fracture site was considered, which reflected a more realistic bone healing process.     

Influence of initial ovality on creep life of P92 pipe bends subjected to in-plane bending

Initial ovality is an inevitable problem in the process of pipe bends manufacturing which results in the stress redistribution of the pipe bends working at high temperature. In order to study the influence of ovality on creep life of pipe bends, full-size creep experiment of P92 pipe bend subjected to in-plane bending has been conducted. The creep strains and outside diameters of dangerous positions have been measured. The microstructures of three different positions of the pipe bend were compared through SEM and the results showed the number and size of the carbide precipitation were the largest at the flank of the pipe bend, which indicated that the creep damage developed fastest at the flank. The modified Kachanov–Robatnov constitutive equations were used to stimulate the creep of P92 pipe bends with FEA software. The representative stress, damage and multiaxiality distributions of the pipe bends have been discussed. The FEA results were consistent with the experimental results and the influence of initial ovality on creep life of P92 pipe bends were analyzed. The results showed that creep life of pipe bends reduced by the increase of ovality and their relationship coincided with the parabolic law.     

爆炸作用下夹层玻璃幕墙动力响应试验研究

为研究夹层玻璃在爆炸作用下的动力响应特征,对四边简支夹层玻璃面板进行了爆炸作用试验研究。试验按3个爆炸等级进行,研究了夹层玻璃面板在不同爆炸当量下的动力响应特征和破坏形态。试验表明：爆炸作用后冲击波的超压迅速升至峰值,并在数十毫秒内逐渐衰减,夹层玻璃的位移和应力随爆炸等级的增加而增大;在爆炸作用下,玻璃面板开始碎裂时裂纹在中心处呈环状,并由中心向四周均匀扩散,整个裂纹呈放射状展开,随着爆炸等级的增加,最终呈撕裂状破坏,钢化玻璃破碎为颗粒附着在PVB胶层上,没有发生飞溅。同时运用LS-DYNA有限元分析软件对试验模型进行了数值分析,分析所得玻璃面板的中心点最大位移与试验结果差别为38.7%,最大应力与试验结果的差别为20%,所得破坏模式与试验结果相吻合,表明数值模拟方法可靠。     

基于结构频响函数的再生混凝土框架地震作用损伤评估

结构遭受地震作用时,其内部损伤的累积会导致该结构频响函数曲线的变化,这可为评估结构损伤程度提供依据。利用ABAQUS有限元软件,对1榀2层单跨平面再生混凝土框架拟动力试验进行有限元分析,计算结果与试验值吻合良好。通过对再生混凝土框架频响函数曲线的分析可知,结构1阶和2阶自振频率分别在2.5Hz和6.0Hz附近变化,随着地震峰值加速度的不断增大,结构自振频率不断降低,反映损伤累积导致结构刚度的不断退化。基于结构的频响函数,提出可用于评判框架结构在地震作用下损伤程度的指标。分析结果表明：该损伤评估方法能有效评判再生混凝土框架在不同强度地震作用下的损伤程度。     

向心关节轴承撑杆上节点试验研究及有限元分析

将向心关节轴承引入弦支穹顶结构的索杆体系,作为撑杆上节点的刚性转动核心,形成了向心关节轴承撑杆上节点。对该节点进行轴向加载试验,得到其承载力以及全过程应力发展情况。试验结果表明,即使在节点耳板屈服后,刚性转动核心转动性能仍然良好,能够保证该节点在轴压作用下仍然具有较好的转动能力。采用ANSYS软件对该节点试验进行了考虑接触的非线性有限元分析,得到各部件应力状态,补充节点试验数据。试验和数值分析结果表明,该类型节点力学性能良好。最后根据分析结果提出了铰节点刚性转动核心的概念,并给出了该类型撑杆上节点承载力及转动能力的建议设计计算式。     

竞赛机翼结构的优化设计与验证

要使复合材料轻质高强的优势得到充分发挥,在给定设计条件下开展复合材料结构的优化设计研究是十分必要的。以SAMPE超轻复合材料竞赛机翼为研究对象,根据给定的外形及工况,基于Hyperworks软件的Opti Struct分析和优化模块,对机翼的结构形式、铺层位置、铺层方向、铺层厚度等进行了优化设计,结合实际制造时的工艺性等,确定出了一款复合材料模型机翼的优化设计方案。基于该优化设计方案开展了模型机翼的制备与试验研究工作,并根据试验结果进行了进一步的改进,最终得到了该赛事组织以来满足承载及变形要求的最轻的一个机翼。     

PCR轮胎滚阻仿真计算及验证

本文介绍了一种基于ABAQUS软件计算滚动阻力的方法,提取轮胎静载工况下的应变、应力等印痕信息再结合胶料的损耗因子计算轮胎温度场分布及滚动阻力。在185/65R14规格轮胎对仿真结果进行了验证,结果表明FEA与试验测试得到的滚阻数值有差距,但是变化趋势及幅度基本吻合。该仿真方法可以有效预测调整结构、胶料后对PCR轮胎滚阻的影响。     

3D Two-way coupled TEHD analysis on the lubricating characteristics of thrust bearings in pump-turbine units by combining CFD and FEA

The thermal elastic hydro dynamic(TEHD) lubrication analysis for the thrust bearing is usually conducted by combining Reynolds equation with finite element analysis(FEA). But it is still a problem to conduct the computation by combining computational fluid dynamics(CFD) and FEA which can simulate the TEHD more accurately. In this paper, by using both direct and separate coupled solutions together, steady TEHD lubrication considering the viscosity-temperature effect for a bidirectional thrust bearing in a pump-turbine unit is simulated combining a 3D CFD model for the oil film with a 3D FEA model for the pad and mirror plate. Cyclic symmetry condition is used in the oil film flow as more reasonable boundary conditions which avoids the oil temperature assumption at the leading and trailing edge. Deformations of the pad and mirror plate are predicted and discussed as well as the distributions of oil film thickness, pressure, temperature. The predicted temperature shows good agreement with measurements, while the pressure shows a reasonable distribution comparing with previous studies. Further analysis of the three-coupled-field reveals the reason of the high pressure and high temperature generated in the film. Finally, the influence of rotational speed of the mirror plate on the lubrication characteristics is illustrated which shows the thrust load should be balanced against the oil film temperature and pressure in optimized designs. This research proposes a thrust bearing computation method by combining CFD and FEA which can do the TEHD analysis more accurately.     

基于混合消能减震技术的组合结构独柱高架站台抗震性能研究

结合高性能组合结构形式以及混合消能减震体系的双重技术优势,研发了适用于独柱长悬臂式高架站台结构的抗震体系。采用有限元分析软件MSC.MARC分别对该体系进行了强震作用下的静力弹塑性分析和动力弹塑性时程分析。分析结果表明基于MSC.MARC二次开发的纤维模型和采用宏观本构的一维非线性弹簧模型能高效准确地模拟站台结构的非线性动力特征以及损伤破坏规律。混合消能减震技术可显著提高结构的刚度和承载力,在降低主体构件耗能的同时增强结构的整体耗能能力。在体系层面,混合消能减震技术可明显改善结构刚度分布不均匀带来的不利影响,有效地降低结构的整体变形和层间位移角;在构件层面,消能减震体系能减少或避免主体构件的出铰,有效地降低主要承重构件的截面应力水平,降低悬臂梁所承受的扭矩。值得注意的是,在混合消能减震体系中,由于结构的各个薄弱环节均得到了加强,未受到消能减震构件保护的其他结构构件的地震响应可能会被放大。     

高速水力测功器安装机架的动静态结构特性分析

在高速水力测功器功率加减载测试系统中,发动机所产生的功率在被其吸收与测试的过程中会产生不平衡动态载荷,为了吸收在高速水力测功器中所产生的振动能量,其安装机架的强度与刚度必须满足技术要求。根据某型高速水力测功器的相关技术参数要求对其机架进行设计,随后应用ANSYS软件建立高速水力测功器机架的计算模型,并进行有限元计算,确保机架能够满足各向刚性和最低自然频率的要求。此外,采用试验测试手段得到安装机架在设备载重状态下的固有特性,并与数值结果进行对比,其最大误差不超过5%,表明数值计算方法的有效性。在此基础上,系统地研究机架的动态响应特性,为更好地确保整机的安全运行提供了依据。