A Study On Adhesive Strength Of Single Lap Structural Adhesive Join Of Glass Fiber Reinforced Composites

In recent years,the body of the material more and more diversified,from the traditional metal to plastic and then to the new composite materials,the diversity of materials given to the car design more space,but because of different materials between the physical,Chemical and mechanical properties,etc.,at the same time,with the modular,the overall shape of the technology and other mature,auto parts and fasteners significantly reduced the number of components usually need to arrange some of the interface,these parts need There is a corresponding way to solve the connection,therefore,the same or heterogeneous material connection technology put forward new challenges,but also because of this,new materials and dissimilar materials between the connection technology has become a research hot spot.Due to the traditional connection technology such as welding,riveting and bolting connections in the connection with the prone to stress concentration is very obvious shortcomings,and viscose connection as a new connection technology,because of a smooth aerodynamic shape and eliminate the force of the characteristics of concentration In the distribution of heterogeneous materials occupy an important position.In this paper,the application of glass fiber reinforced composite materials in the structure of automobile connection is discussed.Based on the three-dimensional asymptotic damage theory,the finite element analysis software ABAQUS is used to connect the different types of bonding connections.Parametric model to discuss the influence of geometric parameters on the strength of connecting structures.The details are as follows:1.The connection mechanism and process flow of the viscose were analyzed and analyzed.The type and failure form of the adhesive joint were introduced to ensure the correct use of the adhesive joint and the best process data,as the connection strength Of the forecast to provide a reliable scientific basis.The three-dimensional model of the bonding of the traditional metal material was established.The cohesive unit was used to simulate the adhesive layer unit,and the damage initiation criterion based on the secondary stress criterion was used to determine the damage of the adhesive layer.Finally,the adhesive structure was obtained by combining the damage evolution rule Strength of the strength of its prediction,the software simulation analysis results with the existing experimental results were compared to verify the accuracy of the analysis.2.Based on the theory of composite structure,Hashin failure criterion and stiffness degradation theory,aiming at the common failure modes of composite materials,the stress and strain curves and the basic parameters of the materials are obtained.Such as fiber tensile(compression)fracture,matrix tensile(compression)cracking,fiber shear,etc.,proposed a new material based on the mapping method to obtain the equivalent properties of composite materials,and compared the literature in the experiment As a result,the accuracy is verified.3.Establish a three-dimensional model of composite materials with glued joints,simulate cohesive units with cohesive units,identify damage initiation of adhesive layer units based on the criterion of damage initiation corresponding to the secondary stress criterion,and finally determine adhesion with the evolution rule of damage.The structural strength compares the simulation analysis results with the experimental results and verifies the accuracy of the analysis model.Then the same analysis method was used to study the influence of different factors on the strength of adhesive joints.The results showed that:(1)When the stiffness of the two sections of composite adhesive joints is symmetrical,the strength of the adhesive joints follows the thickness of the adhesive layer and the overlap length.The increase in the width tends to increase because these factors directly or indirectly affect the bonding area of the joint,and when the thickness of the adhesive layer alone or the overlap length is increased,the thickness of the adhesive layer increases the increase in the increase in the failure load.The length of the connection increases the amplitude of the failure load,that is,increasing the thickness of the adhesive layer to increase the strength of the joint is more significant.However,practical application should be reasonable choice of glue layer parameters to avoid defects.(2)When the stiffness at both ends of a glued joint is asymmetric,the strength of the glued joint is determined by the base material at the relatively weaker yield strength end,and when the composite material needs to be connected with other materials,it may be considered to increase the rigidity of the connected material.To increase the strength of joints,but due to the difference in stiffness may increase the risk of failure of the adhesive layer,so under the premise of meeting the connection requirements,the rigidity of the base material at both ends of the joint should be as close as possible.4.The degree of influence of various geometric parameters on the joint strength was studied.The minimum number of experiments was selected by Taguchi experimental design method,and the influence degree and trend of each geometric parameter on joint strength were obtained through analysis of the ratio of noise to noise.According to the analysis results,the parameters of the influence of geometric parameters on the mechanical properties of cemented joints from largest to smallest are the thickness of the glue layer,the width of the glue layer and the overlap length.