Re: 533 Rear axle broken thread ...age or materials?
Posted by 32model901 On 2018/7/29 7:12:48
Looks like a typical fatigue break, indicated by the "beach marks". When it comes to fatigue, sharp corners greatly increase the stress concentration and are areas where a crack can initiate, and then spread. When this happens you'll see telltale marks left in the broken parts, that look like beach marks. The attachment goes into this in depth.
Looks like the root of the thread ended in the corner. Since the thread comes to a point in the root localized stress here is going to be high.
For a fastener you always want to have it in tension so it is loaded higher than what will be seen in the application. This way the fastener is never subjected to cyclical reverse loading, which can eventually fatigue the fastener.
Attach file:
Size: 1,230.23 KB; Hits: 135
Looks like the root of the thread ended in the corner. Since the thread comes to a point in the root localized stress here is going to be high.
For a fastener you always want to have it in tension so it is loaded higher than what will be seen in the application. This way the fastener is never subjected to cyclical reverse loading, which can eventually fatigue the fastener.
Attach file:
Size: 1,230.23 KB; Hits: 135This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=204765