Verification on the standard procedure of the measurements in the plane shear test of a cross-play vinylester-carbon laminate
Agnieszka Bondyra, Paweł Gotowicki
Quarterly No. 2, 2010 pages 105-109
DOI:
keywords: vinylester-carbon laminate, regular cross-ply laminate, in-plane shear test, in-plane shear modulus, in-plane shear strength, verification of standard procedures, statistical analysis
abstract The paper presents some experimental studies on a regular cross-ply laminate of the [(0/90)F]4S configuration. Each layer is VE 11-M vinylester resin (the manufacturer: „Organika-Sarzyna” Chemical Plants, Sarzyna, Poland) reinforced with plain weave carbon fabric of parameters: Style 430, Carbon 6K, substance 300 g/m2, warp/weft 400/400 tex, 3.7/3.7 yarn/cm (the manufacturer: C. Cramer GmbH & Co. KG Division ECC). The orthotropic laminate was produced by the ROMA private enterprise, Grabowiec, Poland, using the vacuum molding technology and the technological parameters developed by ROMA taking into account the VE 11-M material specification. The PN-EN ISO 14129:2000 standard and closely related standards were taken into consideration in experimental studies on the static in-plane shear response by a tensile test of a [(}45)F]nS laminate. A program of the experiments was focused on testing a rate of a testing machine crosshead and a number of static stress cycles. An influence of these factors on the in-plane shear modulus was investigated. Based on the conducted investigations, the modified experimental procedure has been proposed for determination of the correct value of the in-plane shear modulus and the in-plane shear strength. This procedure concerns the in-plane shear test and contains the following steps: 1. Execution of the initial loading cycle of the triangular shape (linear increase of the crosshead displacement up to 0.55 mm and a linear decrease to zero), at the crosshead rate of v = 2 mm/min) in order to redistribute the residual (technological) stresses in the specimen. 2. A 30’ break after the initial loading cycle, in order to perform the reverse creep of the specimen. 3. Execution of the main test, i.e., linear increase of the crosshead displacement at the velocity of v = 2 mm/min until the break of the specimen appears or the limited strain γ = 0.0500 is reached. Determination of the τ-γ diagram. 4. Determination of the in-plane shear modulus, G12, based on the γ = 0.0010÷0.0020 interval, using the linear regression due to measurement fluctuations. 5. Determination of the in-plane shear strength, R12, equal to the maximum value in the τ-γ diagram.