A mathematical model for enhancing the torsional stability of a slender, tapered, composite wind turbine blade is presented. The increase of the stability boundary is measured by maximization of the critical wind speed at which failure may occur by aeroelastic divergence in parked-turbine state. The total structural mass of the blade is kept constant in order not to violate other economic and p...

This paper presents an analytical method to calculate the buckling stress of a rectangular thin plate under nonuniform applied axial stresses. Two cases are considered, buckling of a plate simply supported on all four sides and buckling of a plate simply supported on three sides with one unloaded edge free and the opposite unloaded edge rotationally restrained. These two cases illustrate the in...

Downhole drilling motors or mud motors are frequently used during the oil and gas well construction, especially for construction of directional and horizontal segments. However, low operation life of the down hole drilling motors and high rate of wear in their working elements may constrain their application due to technical and economical disadvantageousness. In this work, a high-torque modula...

PURPOSE Vertically skewed eye movements are induced by head tilt toward the shoulder (roll). Because vertical and torsional eye movements are tightly coupled both mechanically and neuronally, the purpose of the present study was to investigate the conjugacy of torsional eye movements during the Bielschowsky head tilt test (BHTT). Furthermore, the purpose was to investigate the influence of diff...

When proximal bone stock is compromised at revision hip arthroplasty, distal fixation is often relied upon for stability of the femoral component. In such circumstances, torsional forces can result in debonding and loosening. This study compared the torsional behaviour of a cemented, polished and featureless (plain) stem with cemented, polished stems featuring fins or flutes. The finned stem co...

This paper investigates a low degree-of-freedom wheel model, which describes the lateral vibration of towed wheels, called the shimmy. The model takes into account the lateral deformation of the tyre and also the torsional elasticity and the damping of the steering mechanism. The lateral deformation of the wheel is modeled by the stretched-string like tyre model, which considers the relaxation ...

An active flutter suppression using linear sub-optimal control scheme is investigated for a 2dof airfoil system with nonlinear torsional stiffness and limited deflection amplitude of its single actuator. The suppression of limit cycle oscillations in the nonlinear closed-loop system is achieved through maximization of the stability region of its linearized system. The critical value of the cont...

We study the stability of passive motion of a fish model. The (articulated body) fish model accounts for the finite dimensions of the fish, its bending stiffness (via the torsional springs at the joints), the unsteadiness of the flow (via the added mass effect) but it does not take into consideration vortex shedding from the trailing edge of the fish. The stability analysis shows that there is ...