Applied Mechanics and Materials Vols. 764-765

Abstract: The chaos and nonlinear dynamic behaviors of porous air bearing system are studied by a hybrid numerical method combining the finite difference method (FDM) and differential transformation method (DTM). The numerical results are verified by two different schemes including hybrid method and FDM and the current analytical results are found to be in good agreement. Furthermore, the results reveal the changes which take place in the dynamic behavior of the bearing system as the rotor mass is increased. From the dynamic responses of the rotor center, they reveal complex dynamic behaviors including periodic, sub-harmonic motion and chaos. The results of this study provide an understanding of the nonlinear dynamic behavior of PAB systems characterized by different rotor masses. Specifically, the results have shown that system exists chaotic motion over the ranges of rotor mass 10.66≤ M_r<13.7kg. The proposed method and results provide an effective means of gaining insights into the porous air bearing systems.

Abstract: The Space Curve Meshing Skew Gear Mechanism (SCMSGM) is an innovative gear mechanism proposed by the present authors. In this study, the contact ratio for the SCMSGM is deduced. By analyzing the eight influencing parameters on the contact ratio for the SCMSGM, the principal influencing parameters on the contact ratio for the SCMSGM are obtained. This study provides a theoretical basis to calculate and select the contact ratio for the SCMSGM.

Abstract: The purpose of this study is to investigate the effect of crank arrangement on the dynamics of a quadruped walking machine. The dynamic characteristics of the walking machine, including the stance leg sequence, pitch angle and dynamic response of the quadruped walking machine are investigated and compared with the existing design. The results show that the phrase angle between front and rear legs on the same side should be 0^o or 90^o and the one between the legs on the different sides should be 180^o. The results of this study can serve as a reference for future design and optimization of quadruped walking machines.

Abstract: This paper explores the stroller mechanism by using the creative mechanism method. These creative mechanism methods include the freedom method and the link assortment method. The analysis modeling is the simply four link mechanism. From this analysis result, this can be known that the stroller mechanism changes from four link to three link on the operation type. The mechanism of the stroller becomes the structure of the stroller by using the latch lock. Therefore, the creative mechanism method can be used to analyze the one degree freedom mechanism. This paper uses the six link to analyze the stroller mechanism. Last, this can get the nine new mechanism of the stroller

Abstract: The main function of a suspension system is to isolate and absorb the impact from road surface to vehicle body. To provide good riding comfort, a damper with variable and wide-range damping is highly needed. This paper presents a complete procedure from design, optimization to experiment for a magnetorheological (MR) damper with multiple poles. This new designed damper is entirely different from those conventional single-pole MR dampers, effectively by extending the range of damping force. Magnetic simulation has been done in the paper to provide an optimal structure of the damper which significantly enhances the damping force while avoids magnetic saturation. The new damper was also manufactured and tested. The experimental results show that the provided damping force can be significantly increased with the increase of input current from low to high speeds. Damping force can be varied by 7.41 times. It proves that this new MR damper with high damping force can be controlled adaptively at wide range of operation conditions. It is suitable to be an adaptively variable damping source in semi-active suspension systems.

Abstract: This paper presents the embodiment designs of 3-speed transmission hubs which consist of basic planetary gear mechanisms and gear-shifting control mechanisms. Two feasible clutching sequence tables are synthesized by analyzing the kinematic structure of the gear mechanism. A mechanical control mechanism is used to control the engagement or disengagement of each clutch to guide the power flow from the rear sprocket via the gear mechanism to the hub shell. The power transmission path at each gear stage is further checked to verify the validity of the transmission hub. The embodiment designs of two 3-speed transmission hubs are presented.

Abstract: The pressure angle is one of the primary considerations in designing a cam mechanism since an inappropriate angle may cause excessive sliding loads on the follower. This paper presents a simple yet straightforward method for the design and analysis of a cam mechanism with a translating follower having double rollers. In the proposed approach, conjugate surface theory is employed to derive a kinematic model of the cam mechanism. Analytical expressions for the pressure angle is then derived. The validity of the analytical expressions is confirmed by machining a designed cam using a 3-axis CNC machine tool

Abstract: Due to that the load capacity of the conventional herringbone-grooved cylindrical journal bearing (HGJB) decreases significantly with a decreasing dimension, a requirement exists for miniature HGJB with high load capacity in miniaturized spindle motor applications. This paper investigates the design and characterization of a novel HGJB using dual-layer herringbone-grooved patterns for small spindle motors and cooling fans. In contrast to conventional HGJBs, the proposed HGJB contains another set of herringbone-grooved pattern on its outer surface. The performance of the proposed HGJB is characterized numerically using flow field analysis software. Results show that compared to the conventional HGJB presented by the current group in a previous study, the proposed HGJB can improve the load capacity by 53.7% of the previous value.

Abstract: The waste heat generated by high power LEDs is hardly effectively dissipated, therefore, it results in a serious problem in the luminous efficiency. The most important issue of the LED research is to find a potential design of heat removal and solve the problem of LED over-heating. The purpose of this study is to design the LEDs combined with the cooling module of the aluminum-acetone flat plate heat pipe by the experiment for the high efficiency of heat removal. The aluminum-acetone flat plate heat pipe is innovative proposed by our team. The high power LEDs with and without heat pipe cooling module is compared. The heat removal efficiency of the cooling module of the aluminum-acetone flat plate heat pipe reaches 77% and drops the junction temperature of LED about 36 °C. The cooling module of the aluminum-acetone flat plate heat pipe has proven to be effective in solving the heat concentration problems associated with the LED chips. In short, the phase change cooling module will apply on the electronic component of high heat concentration for more effective cooling method.

Abstract: A barrel heating system will be developed by using induction heating instead of current resistance heating. The experiment results showed the induction heating system can change successfully the current resistance heating system in heated the barrel of injection molding machine. A working coil coupled with magnetic concentrator bars was also considered. Finally, the uniformity of temperature distribution is compared between two barrel heating systems.