上下表面平整度对型材压损破坏载荷的影响

摘要

Based on the flatness degree of“Z” and“2” Shapes up-down surface using measured value of strain gauge under certain loading,the influence of shapes crippling failure load and failure mode were analyzed.For“Z”shapes having finer up-down surfaces,the maximum dispersity of failure loads is 2.6%;and for“2” shapes having worse up-down surfaces,the value is 3.5%.Among all shapes, the failure modes in same type of shapes are uni-form, the deformation curves in strain gauge zones are same for “Z” shapes, and the curves are different for “2”shapes.It is concluded that if only the purpose of shapes crippling test were to confirm the failure load,the flatness degree of up-down surfaces is adequate to some extend, and if the local deformation process were investigated,the up-down surfaces should be remachined and treated.%以应变片测量值确定“Z”型和“2”型长桁上下表面平整程度，并分析其对长桁压损破坏载荷及破坏形式的影响情况。“Z”型长桁上下表面平整度好，试件的破坏载荷最大分散性达到2．6％，而上下表面平整度差的“2”型长桁分散性达到3．5％，二者差别甚小。在破坏形式上，通过对同种类型的长桁形式进行组内对比，发现同种类型试件的破坏形式基本相同；而对于变形曲线，上下表面平整程度会起到影响作用，“Z”型长桁的所有区域（应变片区域）的变形曲线基本相当，而“2”型长桁相差较大。最后得到结论，长桁压损试验目的是在于确定长桁的压损破坏载荷，此时可以在有限范围内，无需调节上下表面的平整度，若考虑观察中间变形过程，则要对上下表面进行调平或再加工。