The Shift2Rail project Pivot2 introduces an innovative metro vehicle with two single axle running gears with only one suspension step to reduce the vehicle's weight. A U-shaped connection frame is designed in Carbon Fibre Reinforced Polymer to further reduce weight and incorporate the anti-roll bar. Due to the poor ride comfort of the vehicle with standard passive dampers, all six dampers are replaced by hydraulic actuators. Modal control is applied and optimized with genetic algorithms. Despite the good improvements obtained, the weighted vertical acceleration remains above the acceptance level. Two modifications of modal control are studied, i.e., modal control with additional sensor, and blended control. Based on the frequency response of the results, it is proposed a low-pass filtered blended controller to neglect frame accelerations high frequency content. This last improves vertical comfort at the expenses of a more complex control system in comparison to modal control.

Within the Shift2Rail projects Pivot2 and NEXTGEAR, an innovative Metro vehicle with single axle running gear and only one suspension step is proposed. A composite material running gear frame is developed to be used both as structural and as suspension element. The design with only one suspension step can significantly degrade the passengers ride comfort. Thus, active modal control is implemented both in lateral and vertical direction to increase the performance of the system. The running gear frame is modelled in Abaqus® as well as the carbody. Structural modes of both elements are implemented in SIMPACK®. A hydraulic actuator model is developed in Simscape®, where two pressure-controlled valves are used to control the pressure inside the chambers of a double acting hydraulic cylinder. A co-simulation environment is then established between SIMPACK® and Simulink®. The vehicle is running with speeds between 10 and 120 km/h. Active modal control makes it possible to maintain ride comfort levels of conventional bogie vehicles with this innovative single axle and single suspension step running gear, promising substantial weight savings of about 400 kg/m. The single axle running gear solution with active comfort control developed here can be an attractive alternative to bogies, providing reduced Life Cycle Costs.

The current study focuses on the bearing failure process of NCF composites and associated damage mechanisms. A set of experiments on bolted joints between NCF composite and steel plates have been performed. The bearing damage onset and failure progression in the composite was monitored at different load levels by microscopic image analysis. Fibre kinking in 0 degrees. layers was found as the key damage mechanism that initiates and drive the bearing failure. Matrix cracking and delaminations were found as well. A cost-effective FE model that predicts bolt bearing failure of NCF composites was proposed. The model utilises state-of-the-art failure criteria and predicts both intra- and inter-laminar progressive damage. A good correlation between the predicted damage development process and experiments was observed both in terms of failure modes and load levels.

The current study is focused on the compressive strength of composite materials containing non-crimp fabric (NCF) reinforcement, and how ply stacking sequence and fibre waviness influence onset and growth of damage in such materials. Experiments reveal significant effects from stacking sequence, both on the compressive strength as such, and on the underlying failure mechanisms. The fibre waviness also has a strong influence on the strength. Fibre kinking is seen before ultimate failure for all configurations but some of them also show local delamination prior to kinking. A finite element simulation methodology is developed and used for the studied cases. It handles local variations of fibre orientations by corresponding re-orientation of stiffness matrices at element level. The simulations provide good predictions of intra- and inter-laminar failure considering both in- plane and out-of-plane fibre bundle waviness. The model is further used in a parametric study of the influence from bundle waviness on the compressive strength.

The design of reliable and efficient mechanical joints with non-crimp fabric (NCF) composites depends on several factors but knowledge on actual loading direction and an accurate compressive strength prediction is essential. Motivated by this, the current study is focused on the compressive strength of cross-ply NCF composites and the influence of fibre orientation in relation to the loading direction. Possible influence of stacking sequence on the compressive strength is also studied. Compression tests of cross-ply NCF composite laminates that are loaded at various off-axis angles are performed and the failure mechanisms are identified. An analytical semi-laminar based model for strength prediction of NCF composite laminates loaded in compression is then suggested. The model take in- and out-of-plane bundle waviness into account. Good agreement between the proposed model and experiments is observed.

Bistable tape springs are ultrathin fiber-reinforced polymer composites, which could self-deploy through releasing stored strain energy. Strain energy relaxation is observed after long-term stowage of bistable tape springs due to viscoelastic effects and the tape springs might lose their self-deployment abilities. In order to mitigate the viscoelastic effects and thus ensure self-deployment, different tape springs were designed, manufactured, and tested. Deployment experiments show that a four-layer, [â '45/0/90/45], plain weave glass fiber tape spring has a high capability to mitigate the strain energy relaxation effects to ensure self-deployment after long-term stowage in a coiled configuration. The two inner layers increase the deployment force and the outer layers are used to generate the bistability. The presented four-layer tape spring can self-deploy after more than six months of stowage at room temperature. A numerical model was used to assess the long-term stowage effects on the deployment capability of bistable tape springs. The experiments and modeling results show that the viscoelastic strain energy relaxation starts after only a few minutes after coiling. The relaxation shear stiffness decreases as the shear strain increases and is further reduced by strain energy relaxation when a constant shear strain is applied. The numerical model and experiments could be applied in design to predict the deployment force of other types of tape springs with viscoelastic and friction effects included.

Design of reliable and efficient mechanical joints with non-crimp fabric (NCF) composites depends on accurate compressive strength prediction. Motivated by this, the current study is focused on the compression strength of NCF and the effect of fibre orientation in relation to the loading direction. Influence of stacking sequence on the compressive strength is studied as well. An experimental methodology is developed based on the classic IITRI test setup complemented with digital speckle photography (DSP) for accurate strain measurements. Compression tests of NCF composite laminates loaded at various off-axis angles are performed for different lay-ups. An engineering model for strength prediction of NCF composite laminates loaded in compression is suggested. Good agreement between the proposed model and the experiments was observed.