Instrumented impact testing

Methods employed to determine the impact resistance of plastics include pendulum methods (Izod, Charpy, tensile impact, falling dart, Gardner, Dynatup, etc.) and instrumented techniques. In the case of the Izod test, what is measured is the energy required to break a test specimen transversely struck (the test can be done either with the specimen notched or unnotched). The tensile impact test has a bar loaded in tension and the striking force tends to elongate the bar (Chapter 5, Impact Strength). 

ISO 6603-1, Plastics - Determination of puncture impact behaviour of rigid plastics - Part 1 Non-instrumented impact testing, 2000. 

ISO 179-2 1998 Plastics - Determination of Charpy impact properties - Part 2 Instrumented impact test... 

The so-called brittle point, associated with sample failure in impact tests, may be determined qualitatively using a penetrometer or a Shore durometer (an instrument used to measure resistance of a sample to penetration by a blunt needle) to measure the change in penetration hardness with temperature. Also, a thin film of a polymer may be readily folded at temperatures above T but may crack when folded at temperatures below Tr... 

Stein M.E.Pollack, "Development of an Improved Rifle Bullet Impact-Sensitibity Test , PATR 2247(1956) 17)Anon, Ordnance Proof Manual , OPM 10-86. Aberdeen PG, Md(1957),p 2 (Bullet impact tests for bombs) 18)H.Will G.Silvestro, "Development of Method for Determining the Sensitivity of Explosives to Bullet Impact , Instrumentation Rept No TR 681-58, PicArsn, Dover, NJ(1958) 19)W.R. Tomlinson, Jr, "Properties of Explosives of Military Interest , PATR 1740, Revision 1(1958) by O.E.Sheffield 20)O.E.Sheffield, "Properties of Explosives of Military Interest , PATR 1740, Supplement No l(1958)(Conf) 21)W.H. 

G. C. Adams, Materials Characterization by Instrumented Impact Testing, in... 

Although the processing variables appear to have correlations with morphology, results of impact tests fail to produce a definitive description of the morphological response to impact. However, this problem is shown to be substantially eliminated through the use of instrumented impact testing (17). Such tests measure the time dependence of the impact load borne by the sample and indicate that impact fracture is a... 

Many impact tests measure the energy required to break a standard sample under certain specified conditions. The most widely used tests are the lzod test (pendulum-type instrument with notched sample, which is struck on the free end), the Charpy test (pendulum-type instrument with sample supported at the two ends and struck in the middle), the falling-weight test (standard ball dropped from known height), and the high-speed stress-strain test. 

INVERSE METHOD FOR THE ANALYSIS OF INSTRUMENTED IMPACT TESTS... 

Instrumented impact tests, three-point bending, bending force, analogical model, inverse problem. 

Inverse Methodfor the Analysis of Instrumented Impact Tests of Polymers... 

Compared to other methods used to extract the bending force from impact tests, it can be noted that using the present approach several drawbacks existing with the other methodologies are removed a) the increase of fracture time and addition of nonlinearities characteristic of mechanical damping b) the lack of foundation of methods used to numerically smooth the experimental registers c) the additional cost incurred when samples are instrumented. 

Cain, P.J. (1987) In Instrumented Impact Testing of Plastics and Composite Materials. pp. 81-102, S.L. Kessler, G.C. Adams, S.B. Driscoll, and D.R. Ireland (Eds). American Society for Testing and Materials, Philadelphia. 

Thanks are due to CEAST, Turin, for assistance with the instrumentation of the impact test apparatuses. The PA6.6 G30 material in the form of extruded rods was kindly supplied by Radici NovaCips, Villa d Ogna, Italy and the POM G15 and POM G30 samples in the I orm of extruded rods were kindly supplied by Rhodia, Ceriano Laghetto, Italy. 

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