ASTM D7136/D7136M-05 Measuring Damage Resistance of Composite to Impact Event
Based on the impact portion of Boeing BSS 7260 Type II, Class 2, ASTM D7136/D7136M-05, covers measuring the damage resistance of fiber reinforced polymer matrix composite plates that have been subjected to a drop-weight impact test. Five flat, rectangular specimens of each material/lay-up are to be tested. The potential energy to be used – defined as mass and drop height – is to be 4.94 ft-lb (6.7J) multiplied by the specimen thickness. Supported on a rigid support fixture with the appropriate sized window in the support base the specimen is subjected to an out of plane, concentrated impact using a hemispherical impactor/insert with a diameter of 0.625 inches (16mm). The damage resistance of the plaque is quantified in terms of the size and type of damage left in the specimen after impact thru post examination. Subsequent compression tests per ASTM D7137/D7137M-05 are conducted if required. Knowing the damage resistance properties of a laminated composite plate is useful for both product development and material selection.
When asked to offer a testing solution to this standard we recommend the use of either our CEAST 9340 or our CEAST 9350. For those customers whose impact energy requirements fall between 1.0 – 97.9 ft-lbs (1.356 – 132.8 J) we recommend using the 9340. With impact energies ranging from 1.9 – 1182 ft-lb (2.6 – 1603 J) either our 9350 or the 9350 with optional High energy System with our Data Acquisition System and Visual Impact Software would be our recommendation for those composite customers who need higher impact energies.
For the testing of plaques that are less than 1 inch (2.42 mm) thick we have optional lightweight crossheads to meet those lower impact energies. To prevent a secondary impact of the falling weight onto the composite plate we employ our anti - rebound device. For larger composite products we offer larger, extended support tables. To fully protect the operator from flying debris we include and offer a selection of interlocked safety enclosures.
Though the test defined in the standard calls for visual inspection and measurements after impact to determine if the specimen has failed, by including instrumentation with our Data Acquisition System complete with Visual Impact and a strain gauged tup failure points/modes that may remain hidden under normal test conditions can be found. One piece of information that may not be found without the use of instrumentation is the first crack or incipient damage point.
Impact resistance is one of the most important properties for component designers to consider, as well as the most difficult to quantify. Impact resistance is a critical measure of service life and more importantly these days, it involves the perplexing problem of product safety and liability. With the combined experience of Dynatup® and CEAST, Instron® has more than 80 years experience in designing impact testing systems to simulate real-life impact conditions.
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