Design and Testing of a Controllable Hinge for a Flapping-wing Micro Air Vehicle

Flying drones have been a well-established field of engineering for many years now. With the wave of bio-inspired design came the idea of flapping wing micro air vehicles (FWMAVs). These drones use flapping wings instead of fixed or rotary wings to generate their lift, giving them the potential for agile movement and application in confined...

Reversible shape morphing of a neutrally stable shell by untethered local activation of embedded Ni-Ti wires

This paper presents a novel shape morphing concept, which exploits neutral stability to achieve reversible shape morphing. The concept is based on actively changing the material stiffness on a local level in order to perturb the neutral stability and thus induce the shell to deform. This concept is realized by embedding Ni-Ti wires in a...

Stiffness reduction of cantilever I-beams through lateral torsional buckling for compliant beams

Lateral torsional buckling (LTB) of I-beams is an established buckling phenomenon in civil and structural engineering known for causing structural failures. However when a buckling instability is present the structure contains a form of negative stiffness. Due to the observed tendency of I-beams subject to LTB to twist about their longitudinal...

Patching a Fuselage: Application of Straight Fiber Variable Stiffness Laminates in Large Aerospace Structures

Straight fiber variable stiffness laminates use multiple overlapping patches to tailor the fiber orientations in particular regions of the laminate. A novel, automated framework for the design of manufacturable laminate has been developed using different stages. In the first and second stage an optimal stiffness distribution is determined using...

Commanding variable stiffness in three degrees of freedom through wiggling of a haptic master device: For a care robot application

Teleoperated semi-autonomous care robots aim to alleviate work pressure from care workers. Unlike many traditional stiff position-controlled robots, the care robot is operating in a shared environment with humans that is often unpredictable and unknown. Especially when dealing with tasks that involve contact with the environment, modulation of...

Design, fabrication and validation of an ankle-foot orthosis simulator system to optimize mechanical characteristics of AFOs for humans with impaired locomotion

The muscles around the ankle (calf and dorsal flexors) are essential for performing activities in daily life, like walking. Neurological and muscular pathologies, such as stroke, cerebral palsy, spinal cord injury, muscle atrophy and post-polio syndrome, affect the ability of voluntary muscle control and/or muscle strength of such muscles. This...

LayLa: An open-source offline programming framework for composite deposition

The versatility of automated composite technologies granted the possibility of manufacturing laminates with a continuous variation of fiber orientation, also known as Variable Stiffness Laminates (VSL). Despite offering enough dexterity to be adapted for composite deposition, industrial manipulators are nontrivial to integrate into other...

Semi-analytical modelling of VAT laminates with cut-outs: Behaviour of discontinuous variable stiffness laminates using Enriched Rayleigh-Ritz method

Using Variable Angle Tow (VAT) laminates, the stiffness and strength properties of laminates can be continuously varied to arrive at designs that outperform traditional straight fibre composite laminates in cases where the loads are distributed in a non-uniform manner. Cases of particular interest are laminates under buckling conditions or...

Semi-Analytical Buckling and Optimisation of Variable Stiffness, Variable Thickness Laminates

Variable Angle Tow designs have shown to improve structural performance by providing a better stiffness distribution. However, additional manufacturing constraints are involved compared to straight fibre laminates: mainly the maximum fibre steering curvature that can be achieved. Moreover, if a gap free laminate is constructed, overlaps will be...

A novel design for decoupling the energy storage and return in passive ankle foot prostheses: A redesign of the VSPA foot

Conventional passive prosthetic feet cannot provide net positive mechanical energy, causing a strong reduction in push-off work. This decrease the comfortable walking speed and increases the metabolic cost of walking in amputees, as more than half of the positive work performed during able-bodied gait is done during the powered plantar flexion...

Artificial Intelligence techniques in design optimization of variable stiffness cylindrical shells

The main driver of aerospace structures design is the increase in performances of currently in use components. The behavior of structures is investigated by means of highly accurate finite elements (FE) analysis. The problem related to this kind of simulations is the high computational time required to obtain the structural response associated...

Effect of Steering Limit Constraints on the Performance of Variable Stiffness Laminates

A method to optimise the fibre angle distribution of variable stiffness laminates is proposed. The proposed method integrates a fibre angle retrieval step with a fibre angle optimisation procedure. A multi-level approximation approach is used in combination with the method of successive approximations. First, fibre angle retrieval is done by...

Semi-Analytical Solution to Buckling of Variable-Stiffness Composite Panels (Plates and Shallow Cylindrical Shells)

Variable-stiffness panels have previously shown enhanced buckling performance compared to constant-stiffness panels, due to the beneficial load and stiffness redistribution. Two semianalytical models based on the Galerkin method and the Ritz method have been developed in order to solve the buckling problem of variable-stiffness composite panels ...

Static Aeroelastic Optimization of Composite Wings with Variable Stiffness Laminates

The application of composite material in load carrying structural components of an aircraft is rapidly gaining momentum. While part of the reason for this can certainly be attributed to an increasing confidence of designers in the new material as a result of growing experience, two other crucial points can be made. One, the continuous...

Optimum Design of Steered Fibre Composite Cylinders with Arbitrary Cross-sections

Automated fibre placement (AFP) machines are able to place simultaneously several bundles of fibres, called tows, on a surface. Using AFP machines, it is also possible to manufacture composite laminates with fibres placed in curvilinear paths. The fibre orientations and stiffness properties of these laminates are spatially varied and hence they...

Development of PlastoLock overtube with temperature controlled rigidity for colonoscopy

To diagnose and treat colon cancer a colonoscopy is usually performed. Current colonoscopy is performed by advancing a colonoscope (scope) through the tortuous colon. However, the flexible scope often buckles when advanced. This can cause discomfort and pain for the patient and can make the examination of the colon difficult for the endoscopist....