碳纤维增强复合材料反射镜的刚度分析

用有限元法对层合板结构和蜂窝夹层结构的两种复合材料反射镜的刚度进行分析计算,分析是以Ex1522环氧树脂为基体,M60J碳为增强材料的平面反射镜为例进行的,分析包括不同铺层取向、顺序的层合板反射镜自重下的镜面变形;对蜂窝夹层结构反射镜,分别比较了以芳纶纸、玻璃布、耐久铝三种夹层材料的反射镜刚度,对比了碳纤维复合材料、铍金属、微晶玻璃为面板材料的反射镜刚度,讨论了不同蜂窝单元结构形状对反射镜刚度的影响.分析表明,对于以Ex1522环氧树脂为基体,M60J碳为增强材料的平面复合材料反射镜,要使其具有相对稳定的面形,应采用单元形状为正三角形铝蜂窝,前后面板各为12层;90/45/0/－45］3层合板的夹层结构.     

几何相似体应力-应变分布相同时的载荷关系

为了保证几何相似模型与原件具有完全相同的应力-应变分布,必须对几何相似模型施加与实际构件成对应比例的各种载荷,因此需要寻求几何相似模型在应力-应变分布完全相同时各种外加载荷的比例关系。从相似理论入手,以2端固支的矩形梁下表面边线中点的应力解析表达式为基础进行推导,得出相应的理论载荷关系,并用算例在弹塑性状态下验证了所得关系的正确性。得到的结论是:对于2个几何相似构件,若几何相似系数为kl,则当外加集中载荷的载荷系数为kl、均布线载荷的载荷系数为kl、均布面载荷的载荷系数为1时,2构件的应力-应变分布完全相同。     

土的不同本构关系对三维有限元分析的影响

1概述宏观上假定土体为连续介质材料或者固体材料,根据材料的不同受力阶段和应力-应变关系特性,连续固体材料的本构关系可以分为弹性、塑性和粘性3大类本构关系[1].这里主要考虑理想弹塑性模型中的Mohr-Coulomb模型、Drucker-Prager模型和修正剑桥模型,这3种模型都是土体数值模     

基于ANSYS的结构设计优化

优化设计是工程界较为关注的领域,阐述了ANSYS软件设计优化程序的原理及具体设计步骤,针对两个实例分别采用GUI交互式和命令流式介绍ANSYS在具体结构优化设计中的实现方法。结果表明:基于ANSYS的合理结构设计能够在满足安全性的前提下节省材料。获得很大的经济效率。相对于交互式来说。采用ANSYS程序的命令输入整个优化文件并进行优化的方法是采用计算机解决工程实际问题的简单易行、快速可靠的方法。     

受损托圈承载能力的有限元计算和分析

综合运用计算机仿真、动力学、有限元分析理论和测试技术等科学理论,并以大型的有限元分析软件ANSYS作为仿真和分析的工具,详细研究不同工况下受损托圈的强度,同时校核了受损托圈的承载能力。     

Finite Element Analysis and OADs Optimization of the Temperature in the Plane-strain Orthogonal Metal Cutting Process

IntroductionDuringthemetalremoving process,a greatdealofheatwillbe generatedbythemechanicalworkbeingconvertedintoheatthroughthe plasticdeformationinvolvedduringchipformationandalsoduetofrictionalworkbetweenthetool,chipandworkpiece[1] .Thisheatmaybeveryharmfultothemachine ,toolandtheworkpiecesbeingmachined ,socontrollingthequantityofcuttingheatisaveryimportant probleminmachiningprocess.Overthese years ,manyimprovementsinmanufacturingtechnologiesrequiredinthemodelingandsimulationofmetalcutting p…     

Experimental and numerical investigation of aramid fibre reinforced laminates subjected to low velocity impact

The low velocity impact performance of domestic aramid fibre reinforced laminates is investigated experimentally and numerically. Laminates with different thicknesses are impacted by drop-weight test machine under different impact energies. The time histories of impact force are recorded and ultrasonic C-scan technology is used to inspect the internal damage of the laminates. Numerical simulation is conducted using finite element method (FEM), taking into account both intralaminar and interlaminar damage. The intralaminar damage model is based on the continuum damage mechanics (CDM) approach, which consists of the strain-based Hashin failure criteria and the exponential damage evolution law, and considers the nonlinear shear behaviour of the material. The interlaminar damage is simulated by interface elements with cohesive zone model. The numerical results show good agreements with the experiments, thus verifying the validity of the presented numerical model.     

Investigation of flexural properties and failure behaviour of biaxial braided CFRP

In this research, the experimental tests of quasi-static three-point bending and three-point bending fatigue were carried out for a ±25° biaxial braided carbon fibre reinforced polymer (CFRP) manufactured using vacuum assisted resin transfer moulding (VARTM). A finite element (FE) model was also set up for quasi-static testing and the prediction results revealed that local fibre volume fraction (FVF) is a primary source affecting the mechanical properties of braided CFRP. The fatigue of the braided CFRP was defined as three different stages according to the flexural modulus results. The damage modes of the test specimens were observed via a digital microscope and scanning electron microscope (SEM) and the process-induced defects were summarised. With compiled results and observations, this study provides a better understanding of failure and fatigue behaviour of biaxial braided composites and their flexural properties which offers a good basis for any further research in fibre volume fractions, structure design and manufacturing for braided CFRP.     

A finite element method based comparative fracture assessment of carbon black and silica filled elastomers: Reinforcing efficacy of carbonaceous fillers in flexible composites

This study is focused on numerical investigation on fracture behaviors of carbon black (CB) and silica filled elastomeric composites. Finite element analysis (FEA) in compliance with multi-specimen method is used to calculate J-integral and geometry factor of the rubber composites up to a displacement of 20 mm for single edge notch in tension (SENT) and double edge notch in tension (DENT) specimens. An empirical relationship between crack tip opening displacement (CTOD) and crack advancement is established depending on notch to width ratio (NWR). The stress contours across the notches for SENT and DENT specimens is discussed briefly. It is found that fracture propagation resistance of CB filled elastomer is 125% more than that of silica filled elastomer. Although, Silica filled elastomer have good tensile strength and crosslink density but it fails to replace carbon black in terms of fracture properties. The critical J-integral for CB filled elastomer is 18.7% and 32.2% more than silica filled elastomer for SENT and DENT specimens respectively. The effect of specimen type on various fracture properties is also explored. The factor of safety is found to be significantly more in case of CB filled elastomers making them less vulnerable to crack propagation and catastrophic failure.     

Study on the application of active balancing device to solve the vibration problem for the rotor with bending fault

The rotor with bending faults that occurrs on the rotating machinery usually vibrates seriously. This paper investigates to apply the active balancing device on a flexible rotor with bending faults to solve the vibration problem. Two problems are studied by finite element method firstly： Where the balance actuator is fixed on the shaft and how much the balancing capacity of the active balancing device is needed. The experiment is then carried out on the test rig, which consists of a flexible rotor with bending faults. The test results indicate that the bending rotor peak vibration response can be decreased from 550~m to 40~tm below by using the active balancing device. The peak vibration response decreases approximately by 93 %. The synchronous vibration due to the rotor bending faults can be controlled effectively by using ac- tive balancing device. The active balancing device is especially adapted to solve the problem caused by thermal distortion with time-variation and randomness, which is varied with working conditions, thus it has good practical value in practice.