A Coupled thermo-mechanical finite element model was employed to simulate the possible effects of varying laser scanning parameters on the surface hardening process for AISI 1045 and AISI 4140 steels. We took advantage of the high-power density of laser beams to heat the surface of workpieces quickly to achieve self-quenching effects. The finite element model, along with the temperature-dependent material properties, was applied to characterize the possible quenching and tempering effects during single-track laser surface heat treatment. We verified the accuracy of the proposed model through experiments. The effects of laser surface hardening parameters, such as power variation, scanning speed, and laser spot size, on the surface temperature distribution, hardening width, and hardening depth variations during the single-track surface laser treatment process, were investigated using the proposed model. The analysis results show that laser power and scanning speed are the key parameters that affect the hardening of the material. The numerical results reveal that the proposed finite element model is able to simulate the laser surface heat treatment process and tempering effect of steel.

The variable combined brake system (VCBS) is a mechanism for motorcycles to simultaneously activate the front and rear brake systems by using one brake lever or pedal. The purpose is to reduce the risk of rollover accidents due to misuse of the front brake when panic braking. Due to its ability in a wide variation range of braking force distribution (BFD) ratios between the front and rear wheels, the VCBS can simultaneously achieve high braking effort and driving comfort performances, provided that the BFD ratio is designed appropriately. This paper aimed to develop the design method for the VCBS. A mathematical model of the VCBS mechanism is derived, and a parameter matching design method that applies adaptive control theory is proposed. A prototype of VCBS is designed and built based on the proposed method. The straight-line braking test results show that the motorcycle equipped with the VCBS prototype effectively obtained a high braking performance in deceleration. The obtained maximum deceleration is an average of 6.37 m/s² (0.65 g) under an average handbrake lever force of 154.29 N. For front brake failure, maximum deceleration is obtained at an average of 3.38 m/s² (0.34 g), which is higher than the homologation requirement of 2.9 m/s².

A parallel planetary gear train design is proposed to construct the wind turbine system that has double inputs and one output. The proposed system is flexible for the application, which may use a combination of two rotors, as used for horizontal axis or vertical axis wind turbines. The proposed transmission mechanism merges the dual time varied input wind powers to a synchronous generator. The effect of the gear train parameters on the dynamic power flow variation is modeled and simulated for the proposed wind turbine system. Results indicate the proposed planetary gear train system is a feasible and efficient design for its application to wind turbine systems. The dynamic torque equilibrium equations between meshed gear pairs are employed to analyze the dynamic power flow. The nonlinear behavior of a synchronous generator is also included in the modeling. The dynamic responses of the dual input transmission mechanism are simulated using the 4th order Runge–Kutta method. The study also investigates the effect of system parameters used in this wind turbine system (i.e., the wind speed, the magnetic flux synchronous generator, and the inertia of flywheels) on variations in electrical power output.

The laser hammering technique on the coupling efficiency improvement in a lensed fiber butterfly laser diode module is studied in this work. The post weld shift (PWS) introduced from laser hammering technique is used to compensate the fiber alignment shift after laser welding in the packaging process. A wedge shaped lensed fiber was used in the coupling efficiency analysis of a 980 nm wavelength laser pumping signal. The 3D thermal-elastic-plastic finite element model was proposed to simulate the laser welding and solidification process by employing the MARC finite element package. The temperature dependent material properties were used in the FEM analysis. The commercial optical software, i.e. Zemax, was also employed in laser power coupling efficiency simulation. The effects of laser pulse sequence and power distribution on coupling efficiency improvement were discussed. The results showed that the proper laser hammering sequence combined with the proper pulse power distribution can improve the coupling efficiency significantly. The results also indicate that the proposed finite element model can simulate the fiber alignment shift induced by PWS in laser welding qualitatively and develop a design guideline for manufacturing laser module packages.

The variations of shear loads with the deformation of lead free tin-sliver-copper (Sn/3.0Ag/0.5Cu) and traditional eutectic tin-lead (Sn/37Pb) solder balls are studied in this work. Two load speeds, i.e. 200μm/s and 300μm/s, are used to show the effect of loading speed on the shear strength variation. A shear strength based on the plastic energy is proposed to indicate the strength variation. The shear deformation of the loaded solder balls during the pull test are measured and compared. Experimental results indicate that the lead free Sn/3.0Ag/0.5Cu solder balls can provide much ductile joint than the traditional eutectic 63Sn/37Pb solder ball can.

The effects of centrifugal force and operating temperature on the stress and creep deformation of rotating micro-turbo rotors are studied in this work. The thermal-mechanical- creep coupled finite element model provided in the MARC package is employed. The variation of stresses and creep strain distributions in turbo blades made of different materials, e.g. stainless steel (A304L), Ti-alloy (Ti-2411) and two ceramics (SiC and SiN3) are analyzed and compared. The effect of rotating speed on the natural frequencies of the micro-turbine with different turbo-blade materials are also evaluated and compared in this study. Numerical results indicate that the strength and dynamic behavior of the micro-turbo rotor is very sensitive to the material of turbo blade.