The Research On Mechanical Behaviors Of Composite Double Lap Joints

Composite has been used more and more widely in the structures of aeronautics and astronautics. It appears the linking problem inevitably. There are three ways in the connection: adhesive bonding, mechanical connection and mixed connection. Each way has its own advantages and disadvantages. Due to the characteristics of stress in aeronautical structures. In some areas, adhesive bonding is the very way to meet the needing of the connection. The destruction of the composite structure occurs mostly in joints. Therefore, it is necessary to study the influence factors of structure strength for engineering practice. This article analysises a kind of typical unit in the connection structure-double lap joints. Concretely speaking, it mainly includes the following questions:Analytical method is used to study the double lap joints, which sustain tension under the environment of high temperature. The stress of temperature representate with a series. We solve the related factor through Castigliano theorem and then superimpose the action of the role of stress under the temperature and tension under the stress. It concludes that the joint parts of stress and checks its strength with related failure criterion.Finite element method is used to simulate the double lap joints, establish the element model. With the uniaxial tensile load, we analyze the distribution of the stress, judge the damage of each part,determine the effect of the temperature and connectors geometric parameters (such as cover lap length, cover plate thickness) on the joint. In the two-way load, the stress distribution is under the joint parts of different modes. We check intensity with different strength criterion, judge strength criterion for two-way loading range.The analysis is correct with the test methods above. A number of specimens are made, including the effect of geometrical parameters and temperature in the test. We observe the way of destruction and obtain the corresponding data through a preliminary test. The finite element model and analysis are verified by test. The results can be used for strength check and design improvement of double lap joints.