Applied Mechanics and Materials Vol. 197

Abstract: The cracks in clad layer are the most often defects in laser cladding of low ductility materials. This paper reports the efforts of crack prediction with finite element method. The process is modeled with commercial FEM software package ANSYS and the thermal-mechanical analysis is performed to inquire the strain-stress variation during cladding, especially the variation around the moment of solidification. The analysis result shows that, by the end of cladding, the clad layer is in tension stress and the stress values are varied in directions. The tension stress along the cladding direction is the maximum one, which causes the cracking in clayed layer. Increasing the preheating temperature of substrate is an effective way to avoid the crack generation.

Abstract: Since camera drivers provided by the different manufacturers are not compatible, machine vision systems must be redeveloped according to specific camera. It is great significant to work out the problem, which could improve the versatility of the inspection system. The reconfigurable technology has applied to image processing, image matching and so on. Hence, in the paper the reconfigurable image acquisition module is designed, which reserves some interfaces for the image detection module. Citing the nonel visual inspection system as an example, adopting DALSA and BASLER cameras to acquire the images, the images was displayed properly. Therefore, the compatibility of the image detection system has been improved greatly.

Abstract: Aiming at accurate predictions of coupler/daft gear systems' dynamic behaviour. Based on the analysis of structural and kinematic relations of two typical systems, hysteretic nonlinear draft gear models and 9DOF (Degree of freedom) detailed coupler/draft gear system models were developed. Frictional pairs on coupling surfaces and coupler tails along with interactive aligning shoulder models were integrated into system models. Utilizing two detailed locomotive models simulations were performed on a section of special track to validate the rationalities of coupler/draft gear system models. Simulation results indicate that all parts in coupler/draft gear system models can fullfill their roles, and the system models themselves can reproduce the run-time behaviour of coupler/draft gear systems with high reliability and accuracy.

Abstract: To overcome the limitations of traditional classification about hybrid power system, the analytical method of energy input-output are introduced into. From the viewpoint of energy input and hybrid power output, this paper classified hybrid power system pattern into four types that are applicable to a wider scope of hybrid power technology. Then, an overview of stirling engine (SE) that is well adapt to various energies and friendly to the environment was provided. In order to fully utilize solar energy, biomass energy and other clean renewable energy, a kind of stirling engine integrated with multi-energy platform was designed, by combined with the corresponding combustion chamber device. Finally, SE thermoelectric hybrid power system was constructed to take full advantage of the good characteristics of stirling engine and compensate for its shortcomings, that provides an effective way to the development and utilization of clean energy and advanced power technique.

Abstract: A new soft-braking strategy for modern Wind Turbines (WTs) is proposed. The braking torque is directly controlled by regulating the caliper’s hydraulic pressure via a controllable pressure valve, subject to some thermal constraints about mechanic braking units. The proposed control strategy consists of a pressure controller, a braking controller and an optimization algorithm for generating a braking torque reference. The modeling issues and some of these design/developments based on a lab-sized setup are discussed. Comparing with the existing WT braking solutions, either through an on/off control, or through some soft-braking mechanism which mainly employs a kind of generator-shaft speed control, the proposed approach can control the brake-induced mechanic stress to the transmission system in a more effective manner, and meanwhile, the thermal stress to the braking units is also explicitly cooperated into this design.

Abstract: From the viewpoint of vortex dynamics, the flowing properties and the characters of transition from laminar flow to turbulent flow were analyzed, the concept of the Reynolds number was reviewed and studied. The different form of the Reynolds number was presented to relate it with fluctuating and breaking down processes to show its dynamical mechanism. On the basis of phenomenological properties, the velocity distribution near the wall was studied to show that the profile connects with the flowing structure which is different from the linear form what usually considered to be, thus the velocity distribution near the wall remains open. Finally, the form of the velocity distribution should follow was probed.

Abstract: Automatic path planning has many applications in robotics, computer-aided design(CAD) and industrial manipulation. The property of safety is vital but seldom taken into consideration by typical path planning. In this paper, collision probability is introduced as an evaluation of crowd degree of environments to get a safer path. The smaller collision probability a node has, the more possibly the node can be extended. Meanwhile, the in/out degree of a node is limited to prevent some nodes to be extended excessively. Through evaluating collision probability on-line, a safe path planning based on DRRTs, called Safe-DRRT, is proposed to provide a path not only feasible but also safe. Finally, a path planner is implemented with Safe-DRRT as a guidance and a local planner. In plentifully crowded experiments with moving obstacles, the proposed method has demonstrated to be competent compared to the state of the art.

Abstract: Two types of typical heavy-haul locomotive coupler models were presented, one is round-pin coupler with shoulder-limit, and another is flat-pin coupler with frictional tail pairs and stop-limit, both of them adapting nonlinear hysteresis buffer models. Utilizing a train model consists of 2 detailed locomotives and 1 simplified freight wagon, curving behaviour of different couplers were studied. The results show that, the actual curving behaviour of different couplers could be accurately simulated by the established coupler dynamics models. This paper will play a promoting role for analyzing actual heavy-haul locomotive running behaviours and safety.

Abstract: It is a great challenge to plan motion for humanoid robots in complex environments especially when the terrain is cluttered and discrete. To address this problem, a novel method is proposed in this paper by planning the gait according to the stance sequence and ZMP (Zero Moment Point) reference. It consists of two components: an adaptive footstep planner and a walking pattern generator. The adaptive footstep planner can generate the stance path according to the walking rules and adjust the orientation of body relevantly. As the footstep locations are determined, Linear Inverted Pendulum Model (LIPM) is used to generate the walking pattern with a moving ZMP reference. As demonstrated in experiments on the humanoid robot HOAP-2, our method can successfully plan footstep trajectories as well as generate the stable and natural-looking gait in typical cluttered and discrete environments.

Abstract: This paper introduces the working principle of the micromacined gyroscope, and establishes the drive equation of it. By solving the differential Equation, the analytical solution and the amplitude-frequency characteristics of the driving mode are obtained. By the visual measurement based on high-speed photography and the post image processing, it measures the vibration of the drive mode of the micromachined gyroscope. And it puts forward a novel displacement detect algorithm that based on the image processing, and with Matlab it verifies the analytical solution and the amplitude-frequency characteristics of drive mode of the micromachined gyroscope. This helps the study on the vibration of the micromacined gyroscope, and provides a new way to measure MEMS.