The Creep Parameters of SAC305 Unleaded Solders

The tensile and shear loading creep parameters of unleaded Sn/3.0Ag/0.5Cu solders are extracted from the proposed tensile and shear creep tests in this work. Four creep loading temperatures, that is, , , , and C, are employed to extract the corresponding parameters. The creep parameters for tensile and shear loading models, that is, stress exponent, material constant, and activation energy, are curve-fitted by using the least square error and simplex optimization algorithms. The accuracy of the extracted parameters correlated with the measured strain rate versus temperature curves. Results indicate that the proposed measurement setup and extraction algorithm is feasible to extract the tensile and shear type creep parameters with good accuracy

The squeeze film effect on micro-electromechanical resonators

The air squeeze film damping effect on the dynamic responses of clamped micro- electromechanical resonators is investigated in this study. A dynamic model for a clamped micro-electromechanical resonator with the damping consideration is derived using Lagrange’s equation. The corresponding resonator eigen solutions are formulated and solved by employing the assumed-mode method. The effect of different parameters; i.e. the resonator size, ambient temperature and pressure on the squeeze film damping characteristics were simulated and investigated. The results indicate that the squeeze film damping effect may significantly affect the dynamic responses of micro-scale electromechanical resonator

Kinematic Analyses of a Parallel-type Independently Controllable Transmission

This study proposes a novel design of a parallel-type Independently Controllable Transmission (ICT). The parallel-type ICT can produce a continuously variable transmission ratio and a required angular output velocity that can be independently manipulated by a controller yet not affected by the angular velocity of the input shaft. The proposed parallel-type ICT is composed of two planetary gear trains and two transmission-connecting members. A prototype was built to investigate its kinematic characteristics and verify application feasibility

Plastic Optical Fiber Displacement Sensor Based on Dual Cycling Bending

In this study, a high sensitivity and easy fabricated plastic optical fiber (POF) displacement sensor is proposed. A POF specimen subjected to dual cyclic bending is used to improve the sensitivity of the POF displacement sensor. The effects of interval between rollers, relative displacement and number of rollers on the sensitivity of the displacement sensor are analyzed both experimentally and numerically. A good agreement between the experimental measurements and numerical calculations is obtained. The results show that the interval between rollers affects sensitivity most significantly than the other design parameters. Based on the experimental data, a linear equation is derived to estimate the relationship between the power loss and the relative displacement. The difference between the estimated results and the experimental results is found to be less than 8%. The results also show that the proposed POF displacement sensor based on dual cyclic bending can be used to detect displacement accurately

Dynamic interaction between contact loads and tooth wear of engaged plastic gear pairs

ABSTRACT The interaction between the dynamic contact loads and the tooth profile wears of a meshing plastic gear pair is simulated and investigated in this study. A dynamic model of a plastic gear pair is presented. The effects of position-varying mesh stiffness, damping ratio, load sharing, tooth profile errors and temperature variation, on the dynamic contact loads are included in this model. The tooth wear equation proposed by Flodin et al is used to simulate the tooth wear and the tooth profile variation. The variation of the contact load introduced from the cumulative tooth profile wear is simulated and analyzed. Numerical results indicate that the dynamic load histogram of an engaging plastic gear pair may change greatly with the tooth wear

THE BENDING AND SURFACE CONTACT STRESS VARIATIONS IN A MATING PLASTIC GEAR PAIR

ABSTRACT A dynamic model of an engaging spur gear pair is proposed to study the distributions and variation of bending and surface contact stresses around the fillet and contacting points for plastic gears. The parameters used in this dynamic model include time-varying mesh stiffness, frictional coefficient, and profile-shifted factor, etc. Due to high sensitivity to heat for plastic material, the influence of temperature on plastic gears is has also been taken into consideration in this work. A computational algorithm is developed to simulate the variation of fillet bending and surface contact stresses during the engagement with different speeds. The results indicate that the operating temperature may affect the distribution and the magnitude of bending and surface contact stresses of a plastic gear pair significantly. INTRODUCTION For metallic gears, the bending and surface stresses have been widely discussed. Considering the tooth surface contact stress, operating temperature, and film of lubrication, Seireg and Conry [1] proposed a lumped parameter to indicate the optimal tooth surface durability. In 1970, Gay [2] discussed the sliding wear of an engaging gear pair. To obtain a lumped parameter about the tooth surface wear and pitting, the velocities were investigated at initial contact point (IP), lowest point of single tooth contact point (LPSTC), pitch point (PP), highest point of single tooth contact (HPSTC), and final contact point (FP) along the path of contact. The fatigue-life model of rolling-element bearing was applied to gear elements by Coy, Townsend, and Zaretsky [3]. Using the constant of proportionality related to material, the surface fatigue life was built, and the results of experiment were shown to prove th

Partial Slip Rolling Wheel-Rail Contact With a Slant Rail Crack

This paper investigates the tip characteristics of an oblique crack in the whee

DYNAMIC CHARACTERISTICS OF A MISTUNED HEAT EXCHANGER IN CROSS- FLOW

ABSTRACT The dynamic behaviors of tubes of a heat exchanger are frequently affected by the existence of local flaw. These tubes are worn from the hot-cold fluid shock waves

Temperature Modeling of AISI 1045 Steel during Surface Hardening Processes

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