Effect of Laminate Thickness and Specimen Configuration on the Fracture of Laminated Composites

Effects of Processing Parameters for Vacuum-Bagging-Only Method on Shape Conformation of Laminated Composites

Processes ◽

10.3390/pr8091147 ◽

2020 ◽

Vol 8 (9) ◽

pp. 1147

Author(s):

Yasir Mujahid ◽

Nabihah Sallih ◽

Mazli Mustapha ◽

Mohamad Zaki Abdullah ◽

Faizal Mustapha

Keyword(s):

Composite Structures ◽

Laminated Composites ◽

Statistical Significance ◽

Processing Parameters ◽

Coefficient Of Determination ◽

Thickness Variation ◽

Optimum Selection ◽

Concave Corner ◽

Laminate Thickness ◽

Thickness Variations

Complex composite structures manufactured using a low-pressure vacuum bag-only (VBO) method are more susceptible to defects than flat laminates because of the presence of complex compaction conditions at corners. This study investigates the contribution of multivariate processing parameters such as bagging techniques, curing profiles, and laminate structures on laminates’ shape conformation. Nine sets of laminates were produced with a concave corner and another nine sets with a convex corner, both with a 45° inclined structure. Three-way analysis of variance (ANOVA) was performed to quantify thickness variation and spring effect of laminated composites. The analysis for concave and convex corners showed that the bagging techniques is the main factor in controlling the laminate thickness for complex shape applications. The modified (single) vacuum-bag-only (MSVB) technique appeared to be superior when compared to other bagging techniques, exhibiting the least coefficients of variation of 0.015 and 0.016 in composites with concave and convex corners, respectively. Curing profiles and their interaction with bagging techniques showed no statistical significance in the contribution toward laminate thickness variation. The spring effect of laminated composites was investigated by calculating the coefficient of determination (R2) relative to that of the mold. The specimens exhibited a good agreement with R2 values ranging from 0.9824 to 0.9946, with no major data offset. This study provides guidelines to reduce thickness variations and spring effect in laminated composites with complex shapes by the optimum selection of processing parameters for prepreg processing.

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ANALYSIS OF DAMAGE PREDICTION IN LAMINATED COMPOSITES SUBJECTED TO IMPACT LOADING

EPRA International Journal of Research & Development (IJRD) ◽

10.36713/epra4128 ◽

2020 ◽

pp. 241-249

Author(s):

Mohamed Fayas Saffiudeen ◽

Abdullah Syed ◽

Fasil T Mohammed

Keyword(s):

Boundary Conditions ◽

Contact Force ◽

Impact Loading ◽

Laminated Composites ◽

Laminated Composite ◽

Fiber Reinforced ◽

Transverse Impact ◽

Fiber Volume ◽

Central Deflection ◽

Laminate Thickness

Fibre-reinforced laminated composites are susceptible to transverse impact, at low velocities causing significant damage, in terms of matrix cracks and delamination’s, which are very difficult to detect with the naked eye and can cause significant reductions in the strength and stiffness of the materials. This study aimed at analysing the transient dynamic response of laminated composites due to impact. The effect of fiber volume fraction, laminate thickness, plate boundary conditions, velocity and mass of impactor on the behaviour of composites during low velocity impact is analysed using ABAQUS software. For the analysis, a laminated composite panel made of graphite/epoxy fiber-reinforced laminates is subjected to transverse impact by projectile with a spherical nose. Hashin failure model was adopted for the analysis. The optimal fiber capacity fraction for extreme impact energy for T300/976 type of composite was determined. The velocity required to cause damage initiation was found out for different fiber volume fractions. The variation of contact force and central deflection with velocity and mass of impactor was determined and appropriate empirical models were developed to predict the maximum contact force and central deflection for particular values of impactor velocity and mass. The variation of resistance to failure with laminate thickness was found out and suitable boundary conditions of the plate were identified for different types of impact loading INDEX TERMS—Fiber Reinforced laminated Composite, impactor mass, contact force central deflection

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