Research On Mechanical Properties Of Adhesive Joints With Aluminum Foam Sandwich

Sandwich structure is a lightweight structure with excellent specific strength and specific rigidity.It is of great significance for improving the power and operating speed of equipment,and is widely used in the fields of aerospace and transportation.However,in the actual engineering structure design process,the connection joint of the sandwich structure is the part with many design problems,and many related scholars have conducted extensive discussions on that.At present,according to the different materials of the sandwich structure,the connection method of the joint can be divided into laser welding,mechanical connection and adhesive bonding.The adhesive bonding has attracted more and more attention due to its non-selective material and easy realization characteristics.Because the actual application occasions and connection forms of the sandwich structure connection joint are different,the researchers are often based on engineering to research,and which lack a complete macroscopic performance characterization.Therefore,this paper uses experiments and simulation methods to study the mechanical properties and failure modes of two common forms(T-shaped and flat-faced)sandwich structure adhesive joints.The main contents are as follows:Based on the methods of experiment and simulation,the tensile test of the sandwich structure T-joint was implemented,the corresponding finite element model was established,the failure mode of the sandwich structure T-joint under tensile load was analyzed,and the influence of geometric parameters of reinforcement plates on the mechanical properties of T-joints were discussed.The research results show that the failure of the T-joint occurs in the bonding area of the joint under tensile load,and the sandwich structure does not fail.The horizontal adhesive layer in the joint connection area mainly bears the peeling stress along the y direction,and the vertical adhesive layer mainly bears the peeling stress along the x direction.By changing the thickness of the reinforcement layer,the stiffness of the T-joint increases significantly,and the peak load and failure mode of the joint become unstable.Based on the experimental method,the four-point bending experiment of the sandwich structure and its butts joint was carried out,the effects of panel parameters on the failure mode and crashworthiness of the sandwich structure were analyzed,and the failure process of flat butt joints of sandwich structure with different types and panel parameters were discussed.The research results show that for sandwich structures with different panel parameters,the Al6061 panel has better plasticity,which makes the sandwich structure more prone to occur debonding failure of sandwich,while the CFRP panel is more brittle and more prone to form bending corners,leading to core shear failure of sandwich.For the plane butt joints of different bonding types,the direct butt adhesive joints,Al3003 plate reinforced joints and CFRP reinforced plate joints are due to the stress concentration of the adhesive layer in the foam aluminum butt area and debonding occurred at the adhesive layer,while the Al6061 reinforced joints are caused by the core shear failure of the sandwich.Using Al6061 reinforcement plate is proved to be a very effective way of butt joints.