电阻焊 - 焊缝破坏性试验 - 多点焊接试件疲劳试验方法

[中文适用范围]： 本文件规定了在室温和最大相对湿度为 80% 的情况下，对厚度范围为 0.5 mm 至 5 mm 的多点焊接和多轴样品进行恒定载荷振幅疲劳试验的试验样品和程序。 本文件对较大厚度的适用性可能受到机械性能的限制，例如试样材料的屈服强度和可成形性。 先进高强度钢 (AHSS) 的厚度范围通常低于 3.0 毫米。 例如，更大的厚度适用于铝合金。 根据所使用的样本，可以从结果中评估以下各项的疲劳行为： ——承受规定的均匀载荷分布的点焊； ——承受规定的非均匀载荷分布的点焊； ——承受不同定义的剪切、剥离和法向拉力载荷组合的点焊；和 — 测试样本。 可实现不同载荷分布的多点试样如下： a) 定义的均匀载荷分布： 1) 用于剪切和剥离载荷的 H 试样（焊缝承受横向于接头的均匀剪切或剥离载荷）线）; 2) 承受四点弯曲的单帽和双帽试样（点焊缝沿焊缝排方向承受均匀剪切载荷）； 3）扭转下的双盘试样（点焊缝承受均匀剪切载荷）； 4）拉伸载荷下的双盘试样（点焊缝承受均匀剥离载荷）； 5）扭拉联合载荷下的双盘试样； 6) 使用规定的夹具制作平坦的多点样品； b) 规定的非均匀载荷分布： 1) 带有改良夹具的 H 试样； 2) 带有标准夹具的改进的 H 样本； 3) 改进的 H 试样，带有改进的夹具； 4) 带有改良夹具的扁平多点样品； 5) 改进的带有标准夹具的多点平面试样； 6) 改进的多点扁平试样，带有改进的夹具； c) 剪切、剥离和法向拉伸载荷的定义组合： 1) KS-2 样本；  2) 双盘标本； d) 承受未定义的非均匀载荷分布的点焊——单帽、双帽和类似的封闭空心截面，在扭转、三点弯曲和/或内压下。 上述 c) 中提到的样本和测试在本文件中不会进一步讨论，因为这些样本获得的结果特定于所测试的部件，并且可能无法概括或用于导出与承载行为有关的数据焊缝。 通过此类测试获得的结果适合于将测试部件的机械性能与以相同方式测试的类似部件的机械性能进行比较。 然而，这些测试不适用于评估或比较焊缝的承载性能。 使用类似部件的样本获得的疲劳试验结果适合于得出承受循环载荷的结构和部件的材料和厚度组合的选择标准。 该陈述对于通过具有边界条件的样本获得的结果特别相关，即局部刚度与所讨论的结构相似。 仅当使用中的载荷条件与接头区域的设计刚度相同时，疲劳试验的结果才适合直接应用于设计。 注：对样本进行修改，以考虑设计提出的约束或特定要求，例如小于标准重叠、小于或大于标准熔核直径以及特定载荷分布，从而提高设计工程师的测试结果的价值。 [外文原描述]： This document specifies test specimens and procedures for performing constant load amplitude fatigue tests on multi-spot-welded and multi-axial specimens in the thickness range from 0,5 mm to 5 mm at room temperature and a relative humidity of maximum 80 %. The applicability of this document to larger thicknesses can be limited by mechanical properties such as yield strength and formability of the specimen material. The thickness range for advanced high strength steels (AHSS) is generally below 3,0 mm. Greater thicknesses apply for aluminium alloys, for example. Depending on the specimen used, it is possible from the results to evaluate the fatigue behaviour of: — spot welds subjected to defined uniform load distribution; — spot welds subjected to defined non-uniform load distribution; — spot welds subjected to different defined combinations of shear-, peel- and normal-tension loads; and — the tested specimen. Multi-spot specimens with which the different load distributions can be realized are the following: a) defined uniform load distribution: H-specimens for shear- and peel-loading, (welds subjected to uniform shear or peel loading transverse to the joint line); single- and double-hat specimens subjected to four-point bending (spot welds subjected to uniform shear load in the direction of the row of welds); double-disc specimen under torsion (spot welds subjected to uniform shear load); double-disc specimen under tensile load (spot welds subjected to uniform peel load); double-disc specimen under combined torsion and tensile loading; flat multi-spot specimens using defined grips; b) defined non-uniform load distribution: H-specimens with modified grips; modified H-specimens with standard grips; modified H-specimens with modified grips; flat multi-spot specimens with modified grips; modified multi-spot flat specimens with standard grips; modified multi-spot flat specimens with modified grips; c) defined combinations of shear-, peel- and normal-tension loads: the KS-2 specimen; the double disc specimen; d) spot welds subjected to undefined non-uniform load distribution — single-hat, double-hat and similar closed hollow sections under torsion, 3-point bending and/or internal pressure. The specimens and tests referred to under c) above are not dealt with further in this document, because the results obtained with these specimens are specific to the components as tested and may not be generalized or used for deriving data pertaining to the load-carrying behaviour of the welds. Results obtained with such tests are suitable for comparing the mechanical properties of the tested components with those of similar components tested in the same manner. These tests are, however, not suitable for evaluating or comparing the load-carrying properties of the welds. The test results of the fatigue tests obtained with component like specimens are suitable for deriving criteria for the selection of materials and thickness combinations for structures and components subjected to cyclic loading. This statement is especially relevant for results obtained with specimens with boundary conditions, i.e. a local stiffness similar to that of the structure in question. The results of a fatigue test are suitable for direct application to design only when the loading conditions in service and the stiffness of the design in the joint area are identical. NOTE Specimens are modified to take into consideration constraints or specific demands posed by design, e.g. smaller than standard overlap, smaller or larger than standard nugget diameter, and specific load distribution, thus enhancing the value of the test results for the design engineer.