Effect of Kinetic Energy due to Hail Impact on Damage Evolution in Gelcoated Glass Fibre Reinforced Polymer Composite

Leading Edge Erosion is a major concern for the wind energy industry as it affects the aerodynamic efficiency of wind turbine blades and, therefore, the power generated. Hail impact on the leading edge could significantly damage the protective layer and the composite substrate. The focus of this research study is to investigate the effect of...

Analysis and optimization of thermoplastic fuselage struts under crashworthiness requirements

The safety of a commercial aircraft is a factor to consider from the early stages of its design to guarantee that this one's structure can protect the occupants inside in a low-speed crash. In an aircraft's primary structure such as a fuselage, where the occupants and cargo should be protected, the design regulations imposed by the EASA have...

On the surface interaction between Cylindrotheca fusiformis and aerospace aluminum alloys

Microbes, and the biofilms they form on surfaces, generally have a negative impact on performance. Well­-known examples are the increase of drag in ships and pipes, and the accelerated corrosion of metallic structures known as MIC. Among microbes, diatoms form a large unicellular algae group known to play a relevant role in the first stages of...

Modelling Skin-Stringer Separation in a Post-Buckled Composite Stiffened Panel through Single Stringer Specimens

The collapse of composite stiffened panels in compression is complex and involves the interactions of many different failure modes. However, when the panel is allowed to enter the post-buckling regime, skin-stringer separation due to the interaction of the post-buckling deformations with the skin-stringer interface is often the critical failure...

Topology optimization, variable stiffness design and staggered optimization for laminated composite structures: a comparative study

The demand for efficient lightweight structures grows rapidly in the aerospace sector. Topology optimization, introduced in the late 80s, is a method capable of producing such structures and has been mainly studied for isotropic materials. On the other hand, the performance of composite structures, which are already widely employed in the...

Fatigue Behavior of Multi-Spot Welded Joints in Thermoplastic Composites: Effects of Spot Arrangement in a Four-Spot Joint

Welding is a joining method for thermoplastic composites (TPCs) that offers multiple advantages over the more traditional methods of mechanical fastening and adhesive bonding. A particularly promising welding technique is ultrasonic welding, which features very short process times as a result of the high heating rates that can be achieved. This...

Stress wave propagation in aircraft structures under bird impact

As collisions between aircraft and birds happen many thousands of times every year, all aspects of such impact events need to be taken into account in the process of designing an aircraft. One aspect that poses a risk is caused by the vibrations induced during bird impact. These vibrations are propagated through the aircraft structure by stress...

Induction welded unidirectional carbon fiber reinforced thermoplastic L-joints: Joint performance and testing methodology

Induction welding is an effective technique for joining unidirectional carbon fiber reinforced thermoplastic composites and L-joints can be produced through quick and cost-effective processing steps. However, due to high localized stresses in the skin-stiffener interface, these L-joints are often avoided in primary aircraft structures. Also, no...

Durability of stiffened CFRP panels with initial delaminations

A numerical fatigue delamination model is validated by means of experimental tests. Delamination is initiated on the skin-stiffener interface which, under cyclic compressive loading and in the post-buckling regime, grows at a decreasing rate. A cohesive zone formulation is used to model the static and fatigue delamination growth, good agreement...

Methodology for Prediction of the Fatigue Life for Lug Joints Subjected to Combined In-Plane and Out-of-Plane Loading

New methods for aircraft movables introduce oblique- and out-of-plane loads on lug joints. With the introduction of these loads on lugs the need arises for a more detailed fatigue life prediction method. <br/><br/>Therefore, the thesis research focused on creating a methodology for predicting the fatigue life for lug joints subjected to combined...