Metode Pengukuran Kekuatan Tarik Impak dan Mekanisme Retak dari Pelat Komposit GFRP

Abstract

The measurement method of tensile strength of GFRP composite plate under impact loading is presented in this thesis. The impact is produced by accelerating a load transfer bar on the test rig by making use of an air gun apparatus. To obtain a direct impact tensile wave on the specimen, a special test rig is provided. The incident stress transmitted into the test rig as calculated by using two-gage method. The method is based on the theory of one-dimensional tensile stress wave propagation in a bar utilizing a modified Hopkinson pressure-bar technique (KOMPAK). Specimens are composite plate of hand lay-up glass fiber reinforced plastic (GFRP), us thickness is around five to seven mm (six layers). The formation of composite plate is the combination of chop strand mai (CSM) and woven roving (WR). To obtam the impact tensile strength of the GFRP specimen a series of impact tests was carried out; each specimen was equipped with strain guges. The results of tensile stress oblamed in specimens and those of calculation using a two-gage method. The impact tensile strength of specimen also is compared to its static tensile strength, and static tensile test is conducted by using Servopuiser testing machine The obtained data's measurement is processed statistically by using Weibull distribution. It was obtained composite plate GFRP type CSM has the highest tensile impact strength and tensile static strength (143.262-153.52) MPa and (102.26-136.07) MPa. Due to tensile stress, material is crack or failure, and concluded as crack mechanism. Crack mechanism of GFRP composite plate is examined on specimen surface by using digital microscope Keyence and Scanning Electron Microscope (SEM). Result of examination were obtained due to impact tensile load GFRP plate asymmetric has the smallest wide of crack but the deepest are 2,85 pm and 612 pon. And due to static tensile load, GFRP composite plate type WR has the widest and the deepest crack is 11.42 pm and 533 μm