Nowadays, there is a tendency to use various materials in the aircraft structures. It is caused by weight and strength optimisation as well as manufacturing and service (including repairs) cost optimisation.
As the range of materials and parts in aeroplane structures is vast, the problem of joining them is significant. The design of the hole vicinity in composite elements and, therefore, the improvement of load transfer is of great importance.
The main goal of PROJOINT is to design a metal-composite mechanical connection with improved bearing performance of a composite panel. The particular tasks are to study the local phenomena in composite material during the bearing and riveting process as well as to investigate benefits of local laminate modification in the hole vicinity in composite panel.
Although fibre reinforced composites have high tensile strength, the load transfer in mechanical joints is limited due to bearing strength determined by matrix. A proper solution of load transfer into the composite structure using shear stress between metal and composite layers can improve bearing capacity of mechanical joints. Bonding of metal inserts (foils) between laminate layers seems to be the most advantageous solution. The optimal and economically reasonable solution that creates a possibility of transferring the load into the composite material in a gradual way will be searched for. Different titanium or aluminium alloy inserts shape and content will be taken into account. Joining panels will be made of CFRP laminate.
A deep study of load transfer by means of shear stress and numerical FE analysis of various locally modified laminate configurations will be the principal investigation method. However, identification of material properties as well as validation and verification tests using DIC, strain gauges, SE and non-destructive methods will also be included.
The target groups of the project are scientists (due to new competences) and airplane manufacturers and services.