板翅式换热器封头强度的分析设计研究

Research on DBA of Strength for a Plate-fin Heat Exchanger Header

采用塑性功曲率(plastic work curvature,PWC)准则和非线性有限元技术相结合的直接法计算了工业封头产品的塑性压力和塑性接管载荷,并将其与其他方法的计算结果进行了比较。分析结果表明,PWC准则塑性压力在理想塑性分析条件下与Cloud-Rodabaugh极限压力和ASME极限压力很接近;PWC准则塑性载荷以总塑性功作为结构整体塑性失效的全局指标,其应变硬化分析条件下的结果能反映材料应变硬化对封头强度的强化效果,克服了TES(twice elastic slope)准则需凭经验选择变形参数的缺点;直接法避免了弹性应力分类的困难,方法简便。研究表明,基于PWC准则的直接法是解决板翅式换热器封头这种复杂结构分析设计问题的有效方法。

A direct route by combining the PWC（plastic work curvature） criterion and the nonlinear FEA technology,was adopted to calculate the plastic internal pressure and the plastic piping loads of an industrial header product,and the calculated results were compared with that of other methods.The comparisons show that the PWC plastic pressure load results of perfect-plastic analysis are very close to the Cloud-Rodabaugh limit pressure result and the ASME limit pressure result;the PWC plastic loads are characterized by reflecting the structural strengthening effect of the material strain-hardening on the header by using the plastic work as the global indicator of plastic collapse mechanism,and avoids the arbitrary of users＇ experience to select an appropriate deformation parameters for determining the TES（twice elastic slope） plastic loads;the direct route is advantageous of convenient calculation by avoiding the cumbering elastic stress categorization procedure.In summary,the direct method based on the PWC criterion is an effective approach to solving the strength DBA problem of the plate-fin heat exchanger header with complicated structure.