PSI - Issue 54

Isyna Izzal Muna et al. / Procedia Structural Integrity 54 (2024) 437–445 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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transformations from one side of the unit cell namely S1 is used to obtain boundary conditions along these sides. This one side is chosen respectively in the z-axis or U3 direction where the axial tensile loading is applied to the unit cell. The reference point (RP1) is created in order to obtain the stress and strain distribution by translating the loading from tensile pulling movement within S1. Rigid body motions with displacements in three coordinate directions have been constrained in the following Eq.1. The rotations about the y and z-axes are constrained by fixing the rotation of the x-axis about these axes. This can be achieved naturally if the x-axis is chosen to be attached to the longitudinal direction of fibers. Furthermore, the rotation about the x-axis is constrained by fixing the rotation of the y-axis about the x-axis. = = = = = = ; … (Eq.1)

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3. Macromechanical modelling In this study, three models made with shell elements in FEM software were created. The composite was modeled with asymmetric laminate with 4 plies/layers where the fibers are unidirectionally aligned in the loading direction. The first model was subjected only to tensile loading as the intact sample without thermal loading. The second model was a sample subjected to the continuous (prolonged) temperature at 65 ° C then n in-plane tensile mechanical loading was applied. The second model was a sample subjected to the continuous (prolonged) temperature at 145 ° C then an in-plane tensile mechanical loading was applied. The idea of this current work is to determine numerically the additive-manufactured composites response (strain, stress) to the applied thermal and mechanical loads. The numerical analyses can be used instead of destructive mechanical tests for numerical models that were positively validated using experimental results. 3.1. Specimen model The material parameters considered in numerical simulation is based on experimental investigation. Each sample consists of 4 layers with the same fiber alignment in all layers. The volume fraction of the composite was kept constant throughout the experimental work due to having the same printing parameters. The carbon fiber reinforcement content was 18.2% (wt.). The total number of specimens printed was 15 samples of which 5 samples for each group of thermal treatment were required in accordance with the D3039 ASTM standard used for tensile testing. The rectangular specimen geometry was modeled in accordance with testing standard ASTM D3039 having dimension equivalent to which experimental work has been done, with standard analytical approaches and numerical modeling techniques (i.e. orthotropic shell) for uniaxial tensile loading case. The investigated structure is comprised of a combination of matrix and fibers. The individual volume fractions for matrix PLA and continuous carbon fiber (CCF) are obtained from the experiment. In this work, the elastic properties of the CFRP composite were calculated