标准化抗凹痕测试程序

[中文适用范围]： 这些测试程序是基于钢板抗凹痕特性与应变率相关的知识而开发的。程序的“准静态”部分模拟了在低压头速度下发生的真实凹痕现象，例如掌纹、肘印、工厂搬运等。程序此部分中指定的压头速度旨在最大限度地降低材料应变率效应。程序的动态部分模拟了在较高压头速度下发生的载荷条件，例如冰雹撞击、购物车撞击和门对门停车场撞击。本程序涵盖了三种凹痕测试方案。方案A适用于指定的实验室制备（通用）面板，方案B适用于成型的汽车外车身面板或组件，方案C适用于最终产品或整车测试。这些方案针对的是汽车/钢铁产品开发周期中不同阶段获得的钢板样品。我们采用了多方案方法，以最大限度地提高凹痕测试方法的灵活性，从而使钢铁生产商和最终用户都能从标准化方法中受益。然而，将一个时间表的结果推断到另一个时间表的结果可能无效，并可能导致错误的结论。 [外文原描述]： These test procedures were developed based upon the knowledge that steel panel dent resistance characteristics are strain rate dependent. The “quasi-static” section of the procedure simulates real world dent phenomena that occur at low indenter velocities such as palm-printing, elbow marks, plant handling, etc. The indenter velocity specified in this section of the procedure is set to minimize material strain rate effects. The dynamic section of the procedure simulates loading conditions that occur at higher indenter velocities, such as hail impact, shopping carts, and door-to-door parking lot impact.Three dent test schedules are addressed in this procedure. Schedule A is for use with a specified laboratory prepared (generic) panel, Schedule B is for use with a formed automotive outer body panel or assembly, and Schedule C addresses end product or full vehicle testing. These schedules are targeted at sheet steel samples obtained at different points in an auto/steel product development cycle. A multiple schedule approach has been utilized to maximize dent test method flexibility and thereby allow both the steel producers and end users to benefit from a standardized approach. Extrapolating results from one schedule to another, however, may not be valid and could result in erroneous conclusions.For “quasi-static” testing, each test schedule provides a load-displacement curve for a given material, either as-stamped or after assembly, under a prescribed set of conditions such as specified strain state, specimen geometry, boundary conditions, indenter type, etc. In order to obtain the most information about dynamic denting behavior comparable in scope to the quasi-static testing, it is necessary to use high speed measuring and recording equipment. If use of this equipment is cost-prohibitive, other dynamic dent evaluations use a drop weight, pendulum, or air gun to fire a projectile at the test surface. For this latter type of dynamic testing, only the impact energy is calculated and the dent depth measured after impact. This information may be sufficient to measure some aspects of dent resistance in the absence of high-speed measuring and recording equipment, but the indenter speed/energy interaction will not be captured. Uniform methods for calculating panel property characteristics such as stiffness and oil canning load are presented. A format for reporting test results is suggested. Using this procedure, reproducible values of “dent resistance” should be obtained in different laboratories.Cross Reference: 1999-01-0025,930786,ASTME691