Impact damage test

Table 7.14 Test Conditions for impact damage test...

Impact resistance is determined usiag flyer plate impact tests, long rod impact tests, Hopkinson bar tests (50), and the Hquid jet technique (51). Impact damage resistance is often quantified by measuring the postimpact strength of the ceramic. 

Sun. C.T. and Rechak. S. (1988). Effect of adhesive layers on impact damage in composite laminates in Composite Materials Testing and Design (8th Conf.) ASTM STP 972 (J.D. Whitcomb ed.), ASTM, Philadelphia, PA, pp 97-123. 

Many applications of ceramic composites will expose the material to impact damage. Here again, the amount of work which has been done in this arena is limited, and needs to be increased. Impact tests can be performed using drop towers or Charpy impact testing apparatus. Such measurements have been done at room temperature30 and the apparatus can be adapted for use at elevated temperatures. 

An assessment of drop-impact damage risks can be made by direct observation, self-contained instruments (within packs), and special recording instruments to identify how simulated laboratory tests can ultimately be substituted for travel tests. Data loggers are now capable of recording temperatures, RH, impacts and vibrations. 

Greszczuk, L. B.. and Chao, H. (1976). Impact damage in graphite-fiber-reinforced compo-sitc.s. Proc. of the 4th Conf on Composite Materials testing and design. AST Pub. 617. May 1976. pp, 389-408. 

For example, Melin et al. [20] showed that fatigue tests of impact-damaged laminates in tension—compression fatigue at R values of — 1 and —5 have almost identical stress-life (S-N) curves when the lives are plotted in terms of maximum compression stress. Tests at an J value of -1 have a mean stress of zero and equal excursions into tension and compression, whereas tests atR= -5 will have stress cycles with tension... 

Pritchard JC, Hogg PJ. The role of impact damage in post-impact compression testing. 

Symonds DD, Davis G. Fatigue testing of impact damaged T300/914 carbon fibre reinforced plastic. Compos Sci Technol 2000 60 379-89. 

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