Applied Mechanics and Materials Vols. 764-765

Abstract: This study will be UV (355nm) laser processing system as a carrier. Using laser direct forming for CIGS solar cell technology P2 layer of stainless steel studied electrode insulated characteristic. To explore the impact of this process on the way to a stainless steel substrate P2 film sizes using its laser different frequency parameters. The experimental results indicated that the electrode pattern of the experiment was similar to that of the simulation result, and the laser process has good results in scribing processing. The analysis results confirm the effectiveness of the laser apparatus when applied to a CIGS solar cell P2 layer of stainless steel.

Abstract: Traditional bearings with one degree of freedom (1-DOF) translation are due to sliding between rigid bodies; however, the wear, backlash, and low precision are existing defects. For high-precision mechanism to overcome these limitations, a flexible bearing with 1-DOF translation in this paper is designed alternatively by the use of the concept of compliant mechanism because its motion replies on elastic elements. Besides, the fatigue strength, fracture, and crack are frequently appeared as mechanical failures due to high stress at the fixed end of flexible hinges. To reduce mechanical failures, experiments are conducted by an L₂₇ orthogonal array of the Taguchi multiple quality method to optimize design parameters, including an applied force and the length, width, thickness, and filleted radius of flexible hinges considering the stress concentration. The results demonstrate that the resulting stress of the new design flexible bearing is almost 99.7% smaller than that of the original design.

Abstract: The modified Reynolds equation for power-law fluid is derived from the viscous adsorption theory for thin film elastohydrodynamic lubrication (TFEHL) of circular contacts. The lubricating film between solid surfaces is modeled as three fixed layers, which are two adsorption layers on each surface and a middle layer. The differences between classical EHL and TFEHL with non-Newtonian lubricants are discussed. Results show that the TFEHL power law model can reasonably calculate the pressure distribution, the film thickness, and the velocity distribution. The thickness and viscosity of the adsorption layer and the flow index influence significantly the lubrication characteristics of the contact conjunction.

Abstract: The new axial-flow fans are designed by following a systematic procedure to construct the 3D multi-airfoil impeller, which is constructed by NACA four-digital series of 2D profiles. Also a new housing is proposed for enhancing the performance. The numerical flow visualization is observed carefully for modifying the design parameters when the undesirable flow pattern appeared. After that a CNC-fabricated prototype consisting of new housing and axial-flow fan is served for performance comparison. The results show that data from experiment and simulation have the same trend and in good agreement. Furthermore, the airflow rate for mockup is largely improved by 64.57% after imposing the new axial-flow fan and the new housing. Moreover, for design of single axial-flow fan, the maximum static pressure and maximum airflow rate are increased by a significant 33.7% and 55.48%, both much higher than the commercial products, respectively. In conclusion, the enhancement of hidden ceiling fan has been accomplished successfully via the systematic scheme proposed in this effort.

Abstract: A new two-degree-of-freedom hybrid-driven five-bar linkage mechanism is presented. The proposed linkage mechanism has two input links: one rotational input link and one linear input link, driven by a constant-speed motor and a servomotor, respectively. The rotational input link rotates with a constant angular speed, and the linear input link follows a reciprocating motion along a specified linear guide fixed on the rotational input link. The configuration was studied, and a kinematic analysis was performed. An example is provided to verify the feasibility and effectiveness of this methodology.

Abstract: This paper presents a general mathematical model for NC-machining an APT-LIKE rotating cutter. The design model of cutting-edge and helical groove are also developed by using the principles of differential geometry and kinematics. The analytical solution for the resolution profile of helical groove has also been developed. The results of numerical experiment indicate that the proposed systematic design method by using 2-axis NC machine setup are feasible and reliable.

Abstract: The thermal hydraulics (T-H) code, GINKGO, has been developed by China Nuclear Power Technology Research Institute (CNPTRI) for the transient analyses of pressurized water reactors. GINKGO is designed to simulate the non-loss-of-coolant-accidents (non-LOCAs), and the transients caused by the breaks in secondary side. This paper presents the GINKGO models as well as the analysis of double-ended MSLB that identifies the reactor core characteristics under reactivity feedback. The analysis results show that the variations of reactivity and nuclear power are governed by the competition between positive moderator feedback and negative reactivity insertion by borated water. Finally, the boron concentration is high enough to suppress the nuclear power to a lower power level of ~5%, terminating this reactivity insertion accident (RIA).

Abstract: A 250-kW organic Rankine cycle system comprised of a preheater, evaporator, condenser, turbine, generator, and pump was used to study its off-design performance and operational control strategy by the flow rate control approach of the working fluid R245fa. The net power output was 243 kW, and the system thermal efficiency was 9.5% under design conditions. The analytical results demonstrated that the flow rate of the working fluid increased with increasing the heat source temperature (T_W,in); higher T_W,in yielded better heat transfer performance of the designed preheater as well as a higher requirement for the evaporator’s heat capacity; and the net power output increased linearly with increasing T_W,in.

Abstract: As the failure of a hydraulic pump is always instantaneous, the failure data are difficult to obtain. High-efficiency fault diagnosis under small-sample conditions for hydraulic pumps is urgently required in engineering applications. A fault diagnosis approach based on wavelet packet transform (WPT), singular value decomposition (SVD), and support vector machine (SVM) is proposed in this study. First, the nonlinear, non-stationary vibration signal of the hydraulic pump is decomposed into components by WPT. Second, singular value vectors are acquired as feature vectors by applying SVD to the components. Third, the health states of the hydraulic pumps are determined and classified with a SVM classifier. Furthermore, the SVM and Elman neural network classifiers are compared in terms of fault classification to demonstrate the superiority of SVM in dealing with small-sample problems. The results of the plunger pump rig test show that the proposed method can diagnose the faults of the hydraulic pump accurately even when the number of samples is small.

Abstract: A digital simulation method for the performance degradation signal of rolling bearings is developed based on the analysis of experimental data. A self-organizing map neural network is utilized to build the performance degradation assessment model of the rolling bearings based on characteristic parameter extraction. Wavelet packet decomposition is then implemented to extract the wavelet coefficients in the corresponding performance degradation sensitive band. Different health confidence values are injected into the extracted wavelet packet coefficients, and signals are reconstructed according to the simulation needs to obtain rolling bearing vibration data under different degradation degrees. Understanding the exact mathematical model of the measured object is unnecessary in this method; the method is simple and reliable and helps solve the problem of performance degradation data simulation. Finally, an FPGA-based performance degradation signal simulator is designed by combining the analogy procedure, employed to support the verification process of fault diagnosis and prediction capability.