共查询到16条相似文献,搜索用时 62 毫秒
1.
2.
3.
用加权残数法计算变截面梁的固有频率 总被引:1,自引:0,他引:1
本文应用加权残数法导出了考虑剪切变形、转动惯量及弹性地基等因素的变截面梁的自由振动方程。并由一简例说明本文推导方法的精度。 相似文献
4.
基于拉格朗日方程推导出复合材料封闭变截面旋转薄壁梁的自由振动方程。与基于哈密顿原理的动力学建模方法相比,该文所采用的方法更为简洁。此外,在薄壁梁的结构模型中还考虑除横向剪切外的扭转、拉伸和弯曲引起的翘曲,具有考虑翘曲因素多的特点。给出了两种刚度配置下的变矩形截面旋转悬臂直梁的自由振动方程简化形式及其相应的迦辽金法求解的固有频率。基于大型通用有限元软件ANSYS,计算了薄壁变截面旋转悬臂梁的固有频率,并且与迦辽金法的求解结果进行了对比。分析了复合材料的弹性耦合、铺层角度、截面变化和旋转速度对薄壁梁的自由振动的影响。 相似文献
5.
该文针对复合材料变截面薄壁旋转轴在不同约束下的振动与稳定性问题,提出了一个动力学模型。基于变分渐进法和拉格朗日方程,推导了复合材料变截面薄壁转轴的自由振动方程。在转轴的结构模型中,综合考虑了扭转、拉伸和弯曲引起的截面翘曲的影响。采用伽辽金法,分析了截面按线性或者抛物线变化的变截面旋转轴的固有频率和临界转速,其中还考虑了一端固定一端自由和一端固定一端铰支两种边界条件以及复合材料铺层角的影响。此外,通过对比分析模型的计算结果与商用有限元软件ANSYS的结果,该文所提出的分析模型的有效性在一定程度上得到了验证。 相似文献
6.
7.
8.
9.
10.
对层状复合材料矩形截面圆柱螺旋弹簧的自由振动特性进行了研究,方程中首次考虑了簧丝截面的翘曲变形对固有频率和振动模态的影响。在各向异性自然弯扭梁理论的基础上,导出了该弹簧在考虑翘曲效应时的运动微分方程,它们由14个一阶偏微分方程组成。弹簧的固有频率可以使用改进的Riccati传递矩阵法确定,单元传递矩阵则采用Scaling- Squaring方法以及Pad´e逼近表达式进行计算。计算结果表明:对于对称层压复合材料矩形截面的圆柱螺旋弹簧,翘曲变形对其固有频率有一定的影响,在自由振动分析中应该加以考虑。最后研究了各种设计参数对该弹簧固有频率的影响,并发现了一些与各向同性材料矩形截面圆柱螺旋弹簧不同的性质。 相似文献
11.
12.
以橡胶原料为基材、改性胶原纤维为吸波剂,通过混炼、热压成形的方法制备一种新的结构型吸波材料,并对其吸波性能和机械强度进行研究。实验结果表明:胶原吸波剂可均匀地分布在橡胶基材中形成结构型吸波材料,可见实验所用的方法适合于胶原吸波剂与橡胶基材的复合;复合材料有较好的吸波作用,吸波剂含量50%、厚度为2mm的材料对电磁波的最大反射损失为8.62dB、吸收强度大于5dB的频宽为3.2GHz;胶原吸波剂与橡胶基材复合后机械强度明显提高,与胶原吸波材料相比,复合吸波材料的抗张强度提高27.6%、撕裂强度提高99.6%;复合材料的吸波性能、机械强度与胶原吸波剂的含量有关,随着吸波剂含量的增加,吸波性能改善但机械强度减弱。 相似文献
13.
Commercial utilization of the composite leaf springs in the suspension application is significantly decided by its eye end joint performance. Present work attempts to design and evaluate the performance of double bolted end joint for thermoplastic composite leaf spring. Injection molded 20% glass fiber reinforced polypropylene leaf springs were considered for the joint strength evaluation. Servo hydraulic test facility is utilized to evaluate the static and fatigue performance of the bolted joint. Various bolt sizes were utilized for the joint and its performances were evaluated under static loading condition to understand the effect of fit between bolt and its hole of the joints. Ultimate bearing strength of the joint is found to decrease with the increase in the clearance between bolt and part hole. Joints were subjected to various amplitudes of completely reversed fatigue loads to evaluate the endurance strength. Load–deflection hysteresis plot of the joint under fatigue conditions is continuously measured and used as the bearing damage index of the joint. Inspection of the bearing surface tested under static and fatigue loading condition revealed severe matrix deformation and fibrillation. In spite of unidirectional load being acted at the joint, curved nature of the bearing surface induces bi-axial stresses, which results in severe matrix fibrillation at the bearing surface. Failure morphology under static conditions shows net-tension beside the bearing damage. Failure morphology under fatigue condition revealed net-tension, and shear-out failures besides the bearing damages. 相似文献
14.
M. Saitoh T. Yamamoto H. Okino M. Chino M. Kobayashi 《Materials Research Innovations》2002,5(5):208-213
Changing the combination of 2nd layer in a double-layer type microwave absorber, the matching frequency (8.10–10.88 GHz), maximum reflection loss and matching
thickness at the matching frequency could be systematically controlled and compared with those of single-layer type microwave
absorber.
Received: 2 December 2001 / Accepted: 20 January 2002 相似文献
15.
16.
The effect of variable fiber spacing on the supersonic flutter of rectangular composite plates has been investigated using the finite element method and quasi-steady aerodynamic theory. The formulation of the location dependent stiffness and mass matrices due to nonhomogeneous material properties was derived. This study first demonstrates the flutter analysis of composite plates with variable fiber spacing. Numerical results show that the sequence of the natural mode may be altered and the two natural frequencies may be close to each other due to the fiber distribution may change the distributed stiffness and mass of the plate. Therefore, it may change the flutter coalescent modes. It is seen that the flutter boundary may be increased or decreased due to variable fiber spacing. The punch phenomenon on the flutter boundary is obvious in the absence of aerodynamic damping. 相似文献