Available online
Description
The programme deals with tests on materials subjected to alternating stresses. It concludes with a discussion of some in service failures.
The programme deals with tests on materials subjected to alternating stresses. It concludes with a discussion of some in service failures.
| Module code and title: | T351, Materials under stress |
|---|---|
| Item code: | T351; 08 |
| First transmission date: | 05-06-1976 |
| Published: | 1976 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:30 |
| + Show more... | |
| Producer: | Ted Smith |
| Contributors: | Alan Lawley; Clive Richards |
| Publisher: | BBC Open University |
| Keyword(s): | Amsler machine; Cantilever tests; Dynamic stress; Experimental techniques; In-service failures; Materials testing; Rotating bend tests; Static stress; Tensile tests; Wohler machine |
| Footage description: | Alan Lawley introduces the programme. Lawley demonstrates the difference between static and dynamic loading. A scale model of a Spitfire aircraft with a strain gauge mounted on the wing is used to demonstrate both types. Lawley explains how cyclic (dynamic) loading can be schematised in the form of simplified diagrams. He shows several of these diagrams for tension and compression. Lawley goes on to explain why an understanding of cyclic loading and stressing is important for the design engineer. Lawley explains the various types of fatigue tests (axial, rotating bend and cantilever) which can be carried out. He uses some simple models to make his points. Lawley, at the Central Electricity Research Laboratories, simulates an axial fatigue test on an Amsler vibraphone fatigue machine. He shows the failed specimen and points out the characteristics of this fatigue fracture surface. Lawley next demonstrates a rotating bend fatigue test. He explains how the apparatus is set up and the testing procedure. Finally, Lawley very briefly demonstrates a cantilever fatigue test. Lawley, with the aid of several diagrams, shows how fatigue test data is displayed and interpreted. Clive Richards of the Central Electricity Research Laboratories explains why they are interested in having quantitative measures of the growth rate of fatigue cracks. Richards uses a diagram to explain how, in theory, one can calculate rate of fatigue crack growth in a specimen. He goes on to explain and then demonstrate a laboratory demonstration of this technique. Shots of the specimen. Alan Lawley and Clive Richards examine and discuss some in-service failures. The examples include a turbine component and a bicycle pedal. Examples of these component failures are shown. |
| Master spool number: | 6HT/71892 |
| Production number: | 00525_5259 |
| Videofinder number: | 1419 |
| Available to public: | no |
