Papers by Keyword: Composite Laminate

Abstract: Replacing mild steel with composite laminates in automotive structures alters vibration characteristics, posing risks like resonance and structural damage. This study employs finite element (FE) analysis to investigate the influence of fiber configurations on the modal parameters of laminates. For unidirectional laminates (UDLs), natural frequencies exhibit symmetry with extrema at 45° fiber orientation angle (FOA). In multidirectional laminates (MDLs), modal responses depend critically on the position, proportion, and type of FOAs. A modal control method is integrated within the forward design under frequency constraints. A case study of an automotive rear floor demonstrates the method’s ability to achieve efficient frequency tuning without modifying the structural geometry, thereby outperforming conventional methods in cost and flexibility.

Abstract: A reliable hybrid modeling and simulation methodology is developed to predict the progressive damage evolution and ultimate strength in multidirectional fiber-reinforced polymer (FRP) composite laminates. The integrated modeling approach combines continuum damage modeling (CDM), the extended finite element method (X-FEM), and the cohesive zone modeling (CZM) technique, to capture fiber breakage, polymer matrix major cracking, composite ply interlaminar delamination, and the interactions of these failure modes. The Schapery theory is incorporated into the finite element model to accurately simulate the pre-peak nonlinearity of the load-bearing response caused by matrix micro-cracking. Multidirectional composite laminates with open-hole tension (OHT), open-hole compression (OHC), filled-hole tension (FHT), and filled-hole compression (FHC) configurations are examined as case studies. It is demonstrated that this hybrid modeling framework and methodology can effectively and efficiently capture the complex composite damage progression and properly predict the residual strengths of damaged composite laminates.

Abstract: In many structural applications, such as marine, aircraft and so on, structures are designed to withstand high impact loading, because they may be subjected to impact of the projectiles with high velocity [1,2] . Fabrics become good choice to resist impact of ballistic [3] because of light weight and high specific strength .

Abstract: Delamination or interlaminar fracture often occurs in composite laminate due to several factors such as high interlaminar stress, stress concentration, impact stress as well as imperfections in manufacturing processes. In this study, finite element (FE) simulation of mode I delamination in double cantilever beam (DCB) specimen of carbon fiber/epoxy laminate HTA/6376C is investigated using cohesive zone model (CZM). 3D geometry of DCB specimen is developed in ANSYS Mechanical software and 8-node interface elements with bi-linear formulation are employed to connect the upper and lower parts of DCB. Effect of variation of number of elements on the laminate critical force is particularly examined. The mesh variation includes coarse, fine, and finest mesh. Simulation results show that the finest mesh needs to be employed to produce an accurate assessment of laminate critical force, which is compared with the one obtained from exact solution. This study hence addresses suitable number of elements as a reference to be used for 3D simulation of delamination progress in the composite laminate, which is less explored in existing studies of delamination of composites so far.

Abstract: Understanding the failure behaviour of composite laminate is crucial in designing a reliable composite structure. Failure analyses have been carried out widely. Nevertheless, the composite laminate displacements before the occurrence of failure have not been analysed thoroughly, especially when comparing between Glass/Epoxy and Graphite/Epoxy, which are the two most common composite laminates. For example, it could be observed that the lamination schemes and variations of angle orientation could affect the displacements and failure behaviour of the symmetric laminate. Therefore, this paper aims to investigate the effect of lamination scheme and angle variations to the displacements and failure behaviour of two most common composite laminates, which are Glass/Epoxy and Graphite/Epoxy laminates. Finite element modelling and analysis of symmetric Glass/Epoxy and Graphite/Epoxy laminates with various angles of fibre orientation subjected to uniaxial tension are performed. Maximum Stress Theory and Tsai-Wu Failure Criteria are employed to determine the failure load. Prior to that, convergence analysis and numerical validation are carried out. Displacements and failure behaviour of the Glass/Epoxy and Graphite/Epoxy laminates (symmetric) are analysed. The failure curves (FPF and LPF) for both theories (Maximum Stress Theory and Tsai-Wu) are plotted and found to be very close to each other. Therefore, it can be concluded that the current study is useful and significant in enhancing knowledge about the failure behaviour, deformation behaviour and mode of failure of composite laminate.

Abstract: The first damage mode to appear in continuous fibre-reinforced composite laminates subjected to in-plane loading is usually transverse cracking, i.e. matrix cracking in the off-axis plies of the laminate. Since the density of transverse cracks has a great influence on the subsequent failure steps like delaminations, it is important to be able to predict it accurately. In this paper, the evolution of crack density with increasing external load is predicted using a combination of the Coupled Criterion of Finite Fracture Mechanics and the Equivalent Constraint Model.

Abstract: The aim of this study is to develop structural strength analysis technique and real-time measuring system of composite laminate using finite element method (FEM) and fiber bragg grating (FBG) sensor. A composite laminate of cantilever beam was designed and fabricated using glass fiber reinforced plastic (GFRP) for structural mechanics behavior research. Six design cases of different orientations composite laminate were considered for the better combinations by using FEM program. The bending test of a composite laminate of cantilever beam was performed by using FBG sensor to obtained relationship between strain and displacement. The study result shows that the higher stiffness of composite laminate of cantilever beam was obtained in the [0/90/0/90] orientation. The first natural frequency is 34.83 Hz and corresponding mode shape is bending mode in Z-direction. The FEM and FBG sensor have been successfully used in variety of composite laminate design with different layering sequences by this article.

Abstract: This research was done to evaluate flexural properties (flexural strength, flexural modulus, and failure mode) of Bambu Tali (Gigantochloa Apus) composite. Lycal 1101 was used as matrix. Two types of laminate were tested in four point bending, unidirectional (0⁰/0⁰) s and symmetric cross ply (0⁰/90⁰) s. Results were then compared with numerical simulation using MSC PATRAN-NASTRAN to determine flexural strength and failure mode prediction for both specimens. All specimens were manufactured using cold press manufacturing method. Results show there was around 28% reduction in flexural strength from unidirectional specimen to symmetric cross ply. Numerical simulation results on failure mode prediction show good agreements with actual four point bending test.

Abstract: This work investigates the effect of residual stresses on the damage of composite laminate. The incremental hole-drilling method is applied to determine residual stresses in composite laminates [0₂/θ₂]_s and then acoustic emission technique is used for the identification of damage appearance during the tensile testing. The samples with different residual stress distribution are prepared through curing and post curing in order to study the role of residual stress on the damage of composite laminates. Besides the experimental method, the theoretical approach is applied to illustrate the role of residual stress on the damage of composite laminates.

Abstract: In this work, study on impact damage FEM model of composite structure was performed. From the finite element method analysis results of composite laminate, it was confirmed that the results of analysis was reasonable. The velocity of impactor to initiate damage was estimated, and in order to investigate the damage at the predicted velocity, impact analysis using finite element method was performed. According to the impact analysis results of composite laminate, it was confirmed that the damage was generated at the estimated impact velocity. Finally, the comparison of the numerical results with those measured by the experiment showed good agreement.