Analytical model for the mechanical behavior of CFRP double-stepped adhesively bonded lap joint
Topic(s) : Material and Structural Behavior - Simulation & Testing
Co-authors :
Rashmiranjan MOHAPATRA (INDIA), Hetram SONWANI (INDIA), Sai SIDHARDH , V NARAYANAMURTHY , M RAMJI (INDIA)Abstract :
Composite joints have garnered extensive attention in various engineering applications for their capacity to deliver superior joint strength at a fraction of the weight in comparison to metallic joints [1,2]. In these joining processes, adhesive joints are preferred over fastened joints since they provide a uniform stress distribution in the joint region. However, they are limited to the joining of thin structures. Hence, having an accurate predictive model to capture the mechanical behavior of adhesive joints is quite essential and is of practical requirement.
A two-dimensional energy-based analytical model is proposed to evaluate the stiffness and strength of adhesively bonded double-stepped lap joints for carbon fiber-reinforced polymer (CFRP) laminates subjected to tensile loading as shown in Fig. 1. The analytical model is developed based on energy approach, and it involves deriving the energy expressions for all the components in the three-stepped lap joint present at different step positions. Then, these individual energy expressions are combined together to form the total deformation energy for the complete joint configuration. The disbond behavior of the adhesive layer is characterized using bilinear and exponential cohesive zone model (CZM) laws. Subsequently, the model proposed here is solved using the two-dimensional finite element (FE) framework.
The response predicted by the analytical model is then validated with a developed three-dimensional FE model and also with an experimental estimate for overall accuracy. The influence of different CZM laws on joint strength prediction is also explored. The proposed model provides a cost-effective alternative to three-dimensional FE models while significantly reducing the computational time. In addition, the study of the influence of the thickness of the adhesive layer and the length of the joint overlap on the stiffness and strength of the joint is also provided by the analytical model that helps in fixing the design parameters for the chosen application.
A two-dimensional energy-based analytical model is proposed to evaluate the stiffness and strength of adhesively bonded double-stepped lap joints for carbon fiber-reinforced polymer (CFRP) laminates subjected to tensile loading as shown in Fig. 1. The analytical model is developed based on energy approach, and it involves deriving the energy expressions for all the components in the three-stepped lap joint present at different step positions. Then, these individual energy expressions are combined together to form the total deformation energy for the complete joint configuration. The disbond behavior of the adhesive layer is characterized using bilinear and exponential cohesive zone model (CZM) laws. Subsequently, the model proposed here is solved using the two-dimensional finite element (FE) framework.
The response predicted by the analytical model is then validated with a developed three-dimensional FE model and also with an experimental estimate for overall accuracy. The influence of different CZM laws on joint strength prediction is also explored. The proposed model provides a cost-effective alternative to three-dimensional FE models while significantly reducing the computational time. In addition, the study of the influence of the thickness of the adhesive layer and the length of the joint overlap on the stiffness and strength of the joint is also provided by the analytical model that helps in fixing the design parameters for the chosen application.