发动机螺栓连接强度有限元分析

用ANSYS校核6缸发动机的连接螺栓和飞轮的强度,结果表明:在预紧工况和最大扭矩工况下,连接螺栓的受力情况基本相同,飞轮的峰值应力出现在飞轮螺纹附近;当螺栓的拧紧力矩为95 N.m时,飞轮螺纹附近区域的最大拉应力为242 MPa,满足强度要求但裕量较小,螺栓最大应力在其材料的许用应力范围内.在实际安装过程中,螺栓拧紧力矩应小于95 N.m.该仿真分析结果可为6缸发动机飞轮制造提供参考.     

钢管弯制过程有限元仿真及断裂原因分析

针对某金属结构公司在钢管弯制过程中出现的个别钢管断裂现象进行研究,根据现场钢管弯制工艺和工序的情况描述,采用非线性有限元软件Marc对钢管的多工位弯制过程进行模拟仿真.以最恶劣的情况即曲率最大的胎具进行多工位弯制,仿真结果显示6个工位的连续弯制过程最大应力为552 MPa,没有达到材料的抗拉极限626 MPa,该弯制过程不会引起钢管强度失效.模拟钢管多种曲率胎具弯制下的应力应变分布情况和回弹后残余应力应变情况.仿真结果表明,弯制此种钢管最大曲率的圆弧时,钢管上的最大应力为542 MPa,小于材料的抗拉强度626 MPa;最大塑性应变为0.031,小于材料允许的最大伸长应变0.2.经过模拟仿真分析,该公司采用的弯制工艺不会引起材料强度失效断裂.引起钢管弯制断裂的原因为个别材料夹杂或气孔造成的小概率事件.     

校车车身结构的有限元分析

建立某型校车的有限元模型,计算在不同工况下其车身骨架的静态强度.计算结果表明:在弯曲和扭转工况下,该校车最大应力分别为154.8和171.4 MPa,均小于Q235屈服应力235 MPa;最大变形分别为4.925和12.92 mm,满足《客车定型试验规程(GB/T 13043—2006)》中所规定的弯曲和扭转工况下10及12 mm的限额;车身结构整体应力大多集中在30 MPa左右,有较大的安全裕度.分析结果可为该校车车身骨架结构优化提供参考.     

基于Abaqus的足部有限元分析

通过Engauge软件从CT图像上提取出成年男子足部轮廓数据,根据得到的数据运用SolidWorks建立足部模型,然后利用Abaqus进行应力分析.分析人体站立及承受碾压力时足部受力情况,结果表明:该成年男子站立时最大应力及变形均在跖骨,应力为0.919 MPa,变形为1.19mm;足部承受100 N碾压力时,跖骨的最大应力为2.635 MPa,碾压力为1 000 N时,跖骨的最大应力已达到23.572 MPa.人体足部受到碾压时,跖骨极易出现损伤.     

基于有限元的门座起重机结构强度分析及应力测试

为保证某港长时期服役的门座起重机工作的安全,运用有限元分析与实测相结合的方法对其金属结构的应力分布进行分析,辅助起重机安全评估工作。根据实际评估需求,选取起重机最危险工作位置时的作业工况进行分析。通过ANSYS有限元计算结果显示：在选择的载荷组合作用下,整机应力分布比较合理,基本小于100 MPa,最大应力值为145 MPa,小于材料的许用应力值,与实际测试的应力数据比较,两者的数据基本吻合,金属结构可安全使用。     

离心泵叶轮爆裂转速数值仿真和试验

基于SimXpert对某液体火箭发动机离心泵叶轮进行弹塑性有限元分析,计算离心泵叶轮在离心载荷作用下的爆裂转速,并与在超速试验台上得到的爆裂试验结果进行对比.结果表明,考虑材料非线性的弹塑性有限元计算结果与试验结果误差为0.59%,可应用于离心泵叶轮的强度校核和结构优化. 该离心泵叶轮的爆裂转速为2.716倍的工作转速,对其进行结构轻量化或优化十分必要.     

某V型柴油机曲轴疲劳寿命仿真

为了对某V型柴油机将最大爆发压力由15.5 MPa提升至16.5 MPa后曲轴的强度及疲劳寿命进行预测,首先在ADAMS/Engine中根据发动机模型及参数建立了发动机动力学模型,获取曲柄销处的载荷时程数据,然后建立了最大爆发压力为15.5 MPa和16.5 MPa一缸点火及二缸点火共4个工况有限元模型,由各工况的应力结果结合材料的S-N曲线及载荷时程曲线,计算得到各工况曲轴的疲劳寿命。计算结果表明,曲轴在各工况下其最大应力小于材料弯曲疲劳极限,应力集中处主要出现在连杆轴颈过渡圆角处,各工况下曲轴寿命高于1 000小时。     

CAE技术在汽轮机高温强度计算中的应用

为分析某百万千瓦超超临界汽轮机高压缸旋转部件在高温以及高离心力载荷下的强度状况,建立高压缸第一级动叶片的模型.根据蠕变试验数据,采用最小二乘法拟合幂蠕变方程中的各个参数,并详细介绍各参数的拟合、优化和验算过程;用CFD分析软件计算流体域内的对流传热系数并插值到有限元计算程序中,分析叶根倒角处危险区域的蠕变应力状况.数据验算结果表明,利用拟合数据计算得到的蠕变应力值与试验值比较接近,证明该方法可靠;CAE计算结果表明,叶根倒角处危险区域蠕变应力考核合格,并且有充足的安全裕量.     

某隧道盾构刀盘仿真与力学性能研究

针对以长沙某地铁施工的地质条件为依据设计的盾构刀盘,利用SOLIDWORKS建立刀盘三维精确模型,通过ANSYS软件对盾构刀盘在土压平衡和土压不平衡两种工况下的受力特性进行了具体分析,得到两种工况下的应力和变形分布;同时对刀盘进行模态分析,得到了刀盘的固有振动特性。结果表明：危险截面均位于牛腿与面板交界处,土压不平衡下刀盘最大应力为230 MPa,最大变形为2.1 mm;土压平衡下最大应力为143 MPa,最大变形为1.63 mm。刀盘的最大应力小于材料的屈服极限345 MPa,变形相对刀盘尺寸不大,满足强度和刚度要求。根据模态分析可知刀盘的激励频率小于刀盘固有频率,刀盘不会发生共振,刀盘满足动力学要求。     

大跨度异型斜拉桥塔柱后锚点空间应力分析

为准确确定大跨度异型斜拉桥的结构受力情况,以采用三角形异型塔、2根水平压杆和1根后斜拉杆交汇于后锚点的、主跨为225 m的某大跨度异型斜拉桥为例,在空间杆系模型整体结构分析的基础上,采用ANSYS建立结构的几何模型和有限元模型,分析后锚点的空间应力分布情况. 结果表明:后锚点的局部应力除在交接处应力集中达到200 MPa外,其余最大值不超过150 MPa;锚箱整体应力水平不高,但存在局部应力集中的问题;内部分隔加劲板的应力分布均匀;钢锚管和剪力板的应力不超过130 MPa,且分布均匀. 该桥的后锚点结构在设计载荷作用下整体应力水平不高,满足规范要求,结构设计安全合理.     

Investigation of an efficient shape optimization procedure for centrifugal pump impeller using eagle strategy algorithm and ANN (case study: slurry flow)

Investigation an efficient shape optimization method for centrifugal pump and other turbo-machine is significant to reduce time consumption of process and increase accuracy and modification. For analysis an efficient shape optimization procedure, slurry flow in centrifugal pump is investigated. Since a centrifugal water pump has been not designed to carry out slurry flows, its performance decreases and energy consumption of this kind of pump increases. Therefore, improvement of performance and reduction of energy consumed for these pumps are the major issues. Since the performance of a centrifugal pump strictly depends on its impeller shape, in this study, the shape of impeller was optimized in order to achieve a higher efficiency for slurry flow. To optimize the impeller geometry and to improve the performance of Berkeh 32–160 pump as for the case study, Artificial Neural Networks (ANN) and Eagle Strategy (ES) algorithms have been coupled with a validated 3D Navier–Stokes equations for two phase flow based on Eulerian-Eulerian model. In the next step, the pump experimentally tested in an established slurry flow test rig in laboratory. Measured data were used to verify the numerical results of initial pump with slurry flow. Finally, the complete numerical characteristic curves of the pump with the optimized impeller were compared to the validated numerical characteristic curves of that with the initial impeller to verify optimization. An efficiency improvement of 3.33% at only 9.9% increasing of head has been obtained for optimized geometry. The results indicated a reasonable improvement in the optimal design of pump impeller and a higher performance using the ES algorithm. Furthermore the ES and PSO algorithm was compared and results shows that ES is efficient than PSO algorithm in this application and this methodology is more efficient than other surrogate methods.     

Performance of a centrifugal compressor with holed casing treatment in the large flowrate condition

As demonstrated by former work,the holed casing treatment can be used to expand the stall margin of a centrifugal compressor with unshrouded impeller.In addition,the choked margin can also be expanded as experimental results indicated.Moreover,the compressor performance,especially the efficiency,on the whole working range is improved.As shown by experiments,the stall margin and choked margin of the compressor are extended,and the maximum efficiency improvement is 14%at the large flowrate of 1.386.Numerical ...     

Mechanical characterization of post-buckled micro-bridge beams by micro-tensile testing

A micro-tensile testing system has been developed to measure the mechanical properties of post-buckled silicon dioxide micro-bridge beams. A kind of vernier-groove carrier is presented to improve alignment precision and repeatability of the measurement, and the stiffness coefficient of the tensile system is calibrated in situ in order to obtain the deformation of the tensile beams. Through analyzing a series of stress states in the beam over film preparation, post-buckling and unfolding of the beam, the initial residual stress in the film is obtained from the original load–displacement curves. The residual stress of 354 MPa is consistent with that calculated from the theory of finite deflection of buckled beams. Young’s modulus and tensile fracture strength are also obtained from the load–displacement curves. The measured modulus and strength are 64.6 ± 3 GPa and 332–489 MPa respectively. The measured properties of the thermal silicon dioxide film are reasonably coherent with other reports.     

Prediction of service life of large centrifugal compressor remanufactured impeller based on clustering rough set and fuzzy Bandelet neural network

In order to predict the service life of large centrifugal compressor impeller correctly, the rough set and fuzzy Bandelet neural network are combined to construct the novel prediction model which can give full play to theirs advantages. The attribute reduction algorithm based rough set and clustering method is firstly designed to optimize the inputting variables of fuzzy Bandelet neural network. And then the prediction model based on fuzzy Bandelet neural network is proposed, the Bandelet function is used as the excitation function of hidden layer and is combined with fuzzy theory to improve the prediction effectiveness of the prediction model. The training algorithm of fuzzy Bandelet neural network is designed based on improved genetic algorithm, the improved genetic algorithm introduces the adaptive differential evolution method into the traditional genetic algorithm, which can effectively optimize the parameters of fuzzy Bandelet neural network. Finally, the original 30 input variables of fuzzy Bandelet neural network are reduced to 9 input nodes based on rough set using 500 remanufacturing impellers as research objects. The service life of remanufacturing impeller is predicted based on three prediction models, and simulation results show that the fuzzy Bandelet neural network optimized by improved genetic algorithm has highest prediction precision and efficiency, which can correctly predict the service life of remanufacturing impeller.     

基于有限元的杆端关节轴承结构优化

针对某型号杆端关节轴承在疲劳试验时发生断裂的问题,对其原结构进行有限元仿真分析,得到的最大应力位置与实际断裂位置吻合,圆柱段仿真结果误差与应力理论计算结果仅为0.5%,验证仿真结果的可靠性。对杆端体各结构参数依次进行单变量有限元仿真分析,获取各参数对杆端体最大应力和质量的影响,据此确定优化顺序并对关节轴承进行优化。优化后的杆端关节轴承质量增加9.8%,最大等效应力降低14.9%,计算疲劳寿命从500万次提高到4 600万次,大于目标疲劳寿命值3 000万次,优化后的样件均顺利通过疲劳试验。