Papers by Keyword: Beam Deflection

Abstract: The characteristics of the e-beam have been investigated according to the various parameters of the wiggler in a miniaturized free electron laser (FEL) module by using 3-dimensional (3D) simulations. The e-beam emerging from the electron emitter was made parallel by applying a static bias to the middle electrode of the electron lens set. It was found that the width of the wiggler electrodes had great effect on the e-beam trajectory inside the wiggler.

Abstract: The present study experimentally investigated the pre-failure and post-fatigue behavior of reinforced concrete (RC) beams constructed with lightweight aggregate concrete (LWAC) in comparison with that constructed of normal weight concrete (NWC) of the same compressive strength (40 MPa). A total of twelve RC beams were tested under different fatigue loadings. Based on the experimental observations, the midspan total deflection measured in the fatigue testing consisted of the elastic and plastic components. The mechanismof the two deflection components developed with load cycles was different. The experimental results showed that the fatigue resistance of LWAC beams was better than that of NWC beams for the same fatigue loading levels. It was reflected in both the lower evolution of fatigue damage and the smaller growth of midspan residual deflection. After 2 million cycles, an average increase in residual load capacity of about 8% was found in the NWC beams, while that in the LWA beams remained virtually unchanged.

Abstract: Several devices of microelectromechanical systems (MEMS) are analyzed in the presented work, using a novel numerical meshless method called the random differential quadrature (RDQ) method. The differential quadrature (DQ) is an effective derivative discretization technique but it requires all the field nodes to be arranged in a collinear manner with a pre-defined pattern. This limitation of the DQ method is overcome in the RDQ method using the interpolation function by the fixed reproducing kernel particle method (fixed RKPM). The RDQ method extends the applicability of the DQ method over a regular as well as an irregular domain discretized by uniform or randomly distributed field nodes. Due to the strong-form nature, RDQ method captures well the local high gradients. These features of the RDQ method enable it to efficiently solve the MEMS problems with different boundary conditions. In the presented work, several MEMS devices that are governed by the nonlinear electrostatic force are analyzed using the RDQ method, and their results are compared with the other simulation results presented in the existing literature. It is seen that the RDQ method effectively and accurately solves the MEMS devices problems.

Abstract: There is an ongoing drive to reduce the operating costs of aero-engines and this may be achieved partially via an increase in engine efficiency. To achieve this, industry needs to utilise new materials that can withstand higher operating temperatures and stresses. Many of the nickel-based alloys suitable for these applications, eg MAR-M-002, are difficult to join using conventional welding techniques. This paper describes a technique used to successfully weld 2.5 mm thick plates of cast MAR-M-002. The technique used FEA modelling to analyse stresses during welding and multiple axis electron beam deflection to alter the temperature and stress distribution around the fusion zone to prevent the initiation or propagation of cracks. FEA modelling of the process has been used to reduce the total number of practical tests, and hence, to conserve the limited material supply. This technique has made it possible to produce crack free welds in what is usually classed as an 'impossible to weld' alloy.