In this paper, the typical mechanical joint surface is taken as the research object. Through the combination of theoretical analysis and experimental analysis, the dynamic characteristics of typical joint surface parameters with different surface textures and the influence of texture parameters on the dynamic characteristics of the joint surface are studied.
A novel fully compliant slider-crank mechanism with no backlash property is presented. Analysis and design approaches for the fully compliant slider-crank mechanism are proposed. A design table displaying stroke, axis drift of the output segment, and critical stresses of compliant segments are presented. Approaches are verified with FEA simulations and experiment.
The present work provides the separation point and its relative location in a circular diffuser carrying incompressible laminar flow in the presence of a non-uniform external magnetic field. Two different approaches are deployed: a dual integral–numerical method and the least square method (LSM). The influence of magnetic field intensity on the separation position is observed.
This extensive review paper, which involves 204 papers, discusses comprehensively a number of performance indices that are instrumental in the design of parallel kinematics manipulators. These indices measure the workspace as well as its quality including the distance to singularity, dexterity, manipulability, force transmission, accuracy, stiffness, and dynamic performance. This paper would benefit designers, practitioners and researchers in better understanding parallel manipulators.
This paper proposes a novel type of bistable mechanism with linear negative stiffness and large in-plane lateral stiffness. Then, by connecting the negative-stiffness mechanism in parallel with a positive-stiffness mechanism, a novel quasi-zero stiffness compliant mechanism is developed. It has better axial guidance capability and in-plane lateral anti-interference capability compare to the conventional mechanism. Such mechanism can be used as constant-force mechanism and vibration isolator.
The paper presents a general procedure to determine the instantaneous rotation center for planar mechanisms, or its kinematical equivalent in the case of spherical or spatial cases, from the velocity analysis of the mechanism. The procedure is based on the theoretical results of the Lie algebra, se(3), of the Euclidean group, together with the Killing and Klein forms. The paper shows that a previous contribution contains fundamental errors and it was done in order to unify the theory.
Rotary forging is a continuous local pressure plastic forming technology. The equipment to realize the rotary forging technology is called the rotary forging machine. In this paper, the finite element analysis of the frame of the rotary forging machine is carried out, and then the structure and size of the machine frame are optimized. Finally, the experimental results show that the grain size and hardness of the formed workpiece are improved, which shows that the optimization scheme is reasonable.
The bending-torsional-axial coupling nonlinear dynamic model of double-sided meshing nutation drive system has been established. The modal analysis of double circular arc spiral bevel gears is carried out, and the ten order natural frequencies and their corresponding modes are obtained. The natural frequencies of nutation drive system and double circular arc spiral bevel gears are different, and there is no resonance.
This paper examines a code-to-code verification between two thermal models. One used a non-commercial code; the other a commercial. A point heat source was applied to one end of a cylindrical geometry. Melting and re-solidfying of a 316 L stainless steel alloy was considered. Temperature dependent material properties and latent heat were included. Mesh independency was achieved. Positive agreement of thermal histories, temperature profiles, melt pool depth and maximum temperature along the rod.
The performance of different models of grooves with various tip gap height on NASA rotor 37 is investigated by discretizing 3D RANS equations based on finite volume technique. Rectangular circumferential grooves casing treatment (CGCT) profile and smooth wall casing performances are evaluated. Moreover, the adiabatic efficiencies and the stall margins of smooth wall casing, rectangular grooves and rectangular grooves with fillet and chamfer corners are compared to assess the impacts of profiles
In the high-precision servo feed system, when the permanent magnet synchronous motor is operated at low speed in the classical drive feed system, the speed fluctuation caused by the motor torque harmonics seriously affects the speed smoothness of the servo system. In this paper, a novel double-drive differential feed system is proposed to effectively suppress the effect of torque harmonics of PMSM on speed fluctuation of a linear feed system at low-speed operation.
The pressure compensation is the most commonly used method at home and abroad to reduce the impact of external seawater pressure on the hydraulic system. The pressure compensator is the key equipment of the pressure compensation system. In this paper, the pressure characteristics of the bellows-type pressure compensator are analyzed. Through the control variable method, the influence of different design parameters on the dynamic characteristics of the pressure compensator is studied.
In helicopter flight simulators, the joystick is a key element, which is used to achieving a reliable helicopter driving while providing a force feedback feeling. In the flight control process, the current force of the haptic interface needs to be used as the simulation calculation of the feedback force. This paper proposes a different strategy aiming at avoiding the use of an expansive and complex force/torque sensor.
To strengthen the convective heat transfer ability of the limited cooling air in the cabin, temperature field homogenization (TFH) in the core flow region of the engine block area was achieved. The TFH optimization model helped minimize the temperature gradient in the core flow region and maximize it at the heat transfer boundary, and the optimum vector field and flow path were obtained. More comprehensive changes to the structural design were made according to the TFH.
This research investigates the outcome of wire EDM process over the taper cross-sectional workpieces of Titanium Alloy (Ti6Al-4V). The outcomes result in better kerf width, surface finish, wire wear and metal removal rates, which can be controlled by taper angle of the workpiece, current, and pulse-off time. The effect of these parameters over the four outcomes of the wire EDM process have been studied in this research. Mathematical models have been developed to predict the outcomes.