Test Procedures for Evaluating Bolt-Load Retention of Magnesium Alloy
1.1 A bolt-load retention (BLR) test is a practical test to determine the bolt load of a fastener joint with time and at given temperatures. There are three types of BLR tests described in this standard, namely general-purpose test, design-purpose test, and screening material test. A general-purpose BLR test may be used for screening materials, while a design-purpose BLR test is usually used to verify the BLR behavior of a specific joint. The screening material test is an example of the general-purpose test for typical automotive applications. 1.2 The test procedures provides guidance in the following areas: (a) BLR sample and test fixture, (b) test fastener, washer and nut, (c) bolt-load measurement and data acquisition, (d) heating device, (e) initial loading, (f) baseline test, and (g) instrumentation of strain gages and calibration (see Appendix B).