Standard Test Method for Impact Resistance of Monolithic Polycarbonate Sheet by Means of a Falling Weight
5.1 This practice is applicable for qualitatively evaluating coated and uncoated monolithic polycarbonate sheet material, for monitoring process control, for screening studies, and as an aid in the prediction of hardware performance when exposed to impact service conditions.
5.2 A limitation of Type A specimen testing is that a thick sheet may not fail since the available impact energy is limited by the maximum drop height and falling weight capacity of the test apparatus. Use Specimen Type A for material less than 12.7 mm (0.50 in.) thick.
5.3 Within the range of drop heights of this system, tests employing different velocities are not expected to produce different results. However, for a given series of tests, the drop height should be held constant so that velocity of impact (strain rate) will not be a variable.
5.4 As the polycarbonate specimen undergoes large plastic deformation under impact, the down (opposite impact) side is under tensile loading and most influential in initiating failure. For that reason, polycarbonate sheet coated on one side should be tested with the coated side down.
5.5 Direct comparison of specimen Type A and specimen Type B test results should not be attempted. For test programs that will require the comparison of interlaboratory test results the specimen type and the approximate drop height must be specified.
5.6 Monolithic polycarbonate sheet is notch sensitive. Data obtained from other test methods, particularly notched Izod/Charpy test results, and extremely high- or low-strain rate test results, should not be compared directly to data obtained from this method. It is noted that Type A specimens, free of flaws, have not experienced the characteristic ductile-to-brittle transition between thin, less than 3.18 mm (1/8 in.), and thick, greater than 7.94 mm (5/16 in.), sheet as reflected by other test methods.
1.1 This test method covers the determination of the energy required to initiate failure in monolithic polycarbonate sheet material under specified conditions of impact using a free falling weight.
1.2 Two specimen types are defined as follows:
1.2.1 Type A consists of a flat plate test specimen and employs a clamped ring support.
1.2.2 Type B consists of a simply supported three-point loaded beam specimen (Fig. 1) for use with material which can not be failed using the Type A specimen. For a maximum drop height of 6.096 m (20 ft) and a maximum drop weight of 22.68 kg (50 lb), virgin polycarbonate greater than 12.70 mm (1/2 in.) thick will require use of the Type B specimen.
Note 1: See also ASTM Methods: D1709, D2444 and D3029.
FIG. 1 Type B Specimen Geometry and Loading
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3.1 Exception—The inch-pound units in parentheses are provided for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statement, See Section 7.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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