摘要
波形膨胀节的常规应力公式与实际吻合区间范围较窄，超过它的赋值区间，即会产生较大偏差。有限元方法克服了这一局限性，其理论基础是应力矩阵等于单元内的弹性系数矩阵和应变矩阵的乘积。如果有限元网格过大，虽然对平面均布应力分析的影响不大，但是它不能正确分析平面非均匀应力和曲面的弯曲应力，往往会产生很大的偏差。其整体刚度存储程序反映了有限单元的连接原理。通过对波形膨胀节的有限元分析，可以看出，由于位移产生的弯曲应力往往大于单纯由内压引起的薄膜应力。在拉伸变形情况下，最大应力发生在波峰的内侧；在压缩变形的情况下，最大应力发生在波谷的外侧。因此设计人员和制造厂家宜采用预应力的方式进行优化设计和制造。
The coincidence range between the general stress formula and the actual stress for the bellow expansion joint is narrow, and it will causes big difference beyond its evaluated interval. The finite element conquers this limitation, and its theoretical basis is that the stress matrix is equal to the multiplication of the elastic coefficient matrix and the straining matrix. If the grid of the finite element is too large, though it has few affect in planar uniform stress, it can＇t correctly analyze the non-uniform stress of the plane or the bending stress of the curve, which often causes large difference. Its memory program of integrate stiffness shows the connection principle of each element. By analyzing the bellow expansion joint, it shows that usually the bending stress caused by displacement is bigger than the membrane stress caused by the internal pressure. The biggest stress occurs inside of the wave crest in the pulling situation; the biggest stress occurs outside of the wave trough in the pressing situation. So the designers and the manufacturers should adopt the pre-stress mode to optimize the design and the manufacture.
出处
《机械》
2008年第8期20-22,共3页
Machinery
关键词
波形膨胀节
有限元分析
换热器
预应力
bellow expansion joint
finite element analysis
heat exchanger
pre-stress
