Computer-based Creativity Enhanced Conceptual Design Model for Non-routine Design of Mechanical Systems

Computer-based conceptual design for routine design has made great strides, yet non-routine design has not been given due attention, and it is still poorly automated. Considering that the function-behavior-structure（FBS） model is widely used for modeling the conceptual design process, a computer-based creativity enhanced conceptual design model（CECD） for non-routine design of mechanical systems is presented. In the model, the leaf functions in the FBS model are decomposed into and represented with fine-grain basic operation actions（BOA）, and the corresponding BOA set in the function domain is then constructed. Choosing building blocks from the database, and expressing their multiple functions with BOAs, the BOA set in the structure domain is formed. Through rule-based dynamic partition of the BOA set in the function domain, many variants of regenerated functional schemes are generated. For enhancing the capability to introduce new design variables into the conceptual design process, and dig out more innovative physical structure schemes, the indirect function-structure matching strategy based on reconstructing the combined structure schemes is adopted. By adjusting the tightness of the partition rules and the granularity of the divided BOA subsets, and making full use of the main function and secondary functions of each basic structure in the process of reconstructing of the physical structures, new design variables and variants are introduced into the physical structure scheme reconstructing process, and a great number of simpler physical structure schemes to accomplish the overall function organically are figured out. The creativity enhanced conceptual design model presented has a dominant capability in introducing new deign variables in function domain and digging out simpler physical structures to accomplish the overall function, therefore it can be utilized to solve non-routine conceptual design problem.

The optimum design of the pressure control spring of the relief valve based on neural networks

Based on the traditional optimization methods about the pressure control spring of the relief valve and combined with the advantages of neural network, this paper put forward the optimization method with many parameters and a lot of constraints based on neural network. The object function of optimization is transformed into the energy function of the neural network and the mathematical model of neural network optimization about the pressure control spring of the relief valve is set up in this method which also puts for ward its own algorithm. An example of application shows that network convergence gets stable state of minimization object function E, and object function converges to the utmost minimum point with steady function, then best solution is gained, which makes the design plan better. The algorithm of solution for the problem is effective about the optimum design of the pressure control spring and improves the performance target.

Finite Element Analysis and Test of an Ultrasonic Compound Horn

An?ultrasonic compound horn is designed and manufactured, and the horn is analyzed by wave equation, finite element method and test. The modal frequencies and frequencies of the first and second longitudinal vibration of the horn are obtained by the finite element analysis. The horn is made and modal testing is carried out. The modal frequencies of the first and second longitudinal vibration are obtained respectively. The test results are in good agreement with the theoretical calculation. Experimental results show the maximum amplitude of the horn can reach 9?nm with applied excitation voltage of amplitude 7?V and frequency 21,450?Hz, when the amplitude of voltage increases?to 80?V, the horn of maximum amplitude reaches?23 μm. The maximum amplitude of the horn is approximately proportional to the amplitude of excitation voltage. The horn has the characteristics of high sensitivity and large amplitude, and can be used in ultrasonic machining and other fields.

Study on Performance of Laminated Porous Metal Fiber Sintered Felt as Catalyst Support for Methanol Steam Reforming Microreactor

In this study, the laminated porous metal fiber sintered felt(PMFSF) functioning as catalyst support was used in a cylindrical methanol steam reforming(MSR) microreactor for hydrogen production. The PMFSF was fabricated by the low temperature solid-phase sintering method using metal fibers such as copper fibers and aluminum fibers which are obtained by the multi-tooth cutting method. The two-layer impregnation method was employed to coat Cu/Zn/Al/Zr catalyst on the PMFSF. The effect of fiber material, uniform porosity and gradient porosity on the performance of methano steam reforming microreactor was studied by varying the gas hourly space velocity(GHSV) and reaction temperature. Our results showed that the loading strength of porous copper fiber sintered felt(PCFSF) was better than porous aluminum fiber sintered felt(PAFSF). Under the same reaction conditions, the PCFSF showed higher methanol conversion and more H_2 output than PAFSF. Moreover, the gradient porosity(Type 5: 90%×80%×70%) of PMFSF used as the catalyst support in microreactor demonstrated a best reaction performance for hydrogen production.

Research Status and Development Direction of Piezoelectric Wind Energy Harvesting Technology

In recent years, with the rapid development of large-scale distributed wireless sensor systems and micro-power devices, the disadvantages of traditional chemical battery power supply mode are becoming more and more obvious. Piezoelectric energy collector has attracted wide attention because of its simple structure, no heating, no electromagnetic interference, environmental protection and easy miniaturization. Wind energy is a reproducible resource. Wind energy harvester based on piezoelectric intelligent material can be named piezoelectric wind energy harvesting which converts wind energy into electric power and will have great application prospect. To promote the development of piezoelectric wind energy harvesting technology, research statuses on piezoelectric wind energy harvesting technology are reviewed. The existing problem and development direction about piezoelectric wind energy harvester in the future are discussed. The study will be helpful for researchers engaged in piezoelectric wind energy harvesting.

Gate Optimization Analysis of Injection Molding for Mobile Phone Panel Based on Moldflow and Drop Simulation

Aiming at the gate design problem of a mobile phone panel, the plastic forming analysis software Moldflow and drop simulation were used to optimize the gate design. Six different gate design schemes were compared and studied, and the weld lines positions and injection molding results under each gate scheme were analyzed.Through the simulation analysis of the falling process of the mobile phone panel by the display dynamics analysis software ANSYS Workbench LS-DYNA, five analysis schemes were set according to the falling angle, and the stress distribution at the weld lines positions of the mobile phone panel in each scheme was studied. The reasonable gate scheme was given by synthesizing the force condition, the mold flow analysis and the drop simulation results of the mobile phone panel in use. Based on the results of die flow analysis and drop simulation the optimal gate design scheme 2 is found, and the weld line position avoids the lower part of the elliptical hole, which is the weak part of the structure. The research results had certain reference significance for the optimization of injection process of plastic products.

The cycloconverter based on fuzzy controller for lift

In order to ensure the lift can go up and down steadily and safely, a cycloconverter based on fuzzy control algorithm for lift was introduced, which can keep the output voltage to be symmetric sine wave. In this cycloconverter system, the main circuit structure was designed as circumfluence mode, with the strong DSP as the control unit, the fuzzy control policy of average weight accumulation decision was used to control the tuning of the triggering angle for thyristor in the main circuit, and then, the output voltage of the cycloconverter can be controlled. The experiment and simula-tion prove that the performance of the fuzzy cycloconverter is improved a lot and the output voltage is very similar to symmetric sine wave. This kind of cycloconverter can help the lift stop accurately, and the shock can be decreased.

Finite Element Analysis on a Square Canister Piezoelectric Energy Harvester in Asphalt Pavement

A novel square canister piezoelectric energy harvester was proposed for harvesting energy from asphalt pavement. The square of the harvester was of great advantage to compose the harvester array for harvesting energy from the asphalt pavement in a large scale. The open circuit voltage of the harvester was obtained by the piezoelectric constant d33 of the piezoelectric ceramic. The harvester is different from the cymbal harvester which works by the piezoelectric constant d31. The finite element model of the single harvester was constructed. The open circuit voltage increased with increase of the outer load. The finite element model of the single harvester buried in the asphalt pavement was built. The open circuit voltage, the deformation difference percent and the stress of the ceramic of the harvester were obtained with different buried depth. The open circuit voltage decreased when the buried depth was increased. The proper buried depth of the harvester should be selected as 30 - 50 mm. The effects of structure parameters on the open circuit voltage were gotten. The output voltage about 64.442 V could be obtained from a single harvester buried under 40 mm pavement at the vehicle load of 0.7 MPa. 0.047 mJ electric energy could be gotten in the harvester. The output power was about 0.705 mW at 15 Hz vehicle load frequency.

Effect of slope inclination on step friction coefficient of human being

Effect of slope inclination on step friction coefficient of human being was studied by gait friction tester developed by Henan University of Science and Technology.It is beneficial to improving the safety of human beings while walking on a ramp.Based on the trajectory of mass center of body(MCOB)and the mechanical analysis of human body while walking,conclusion could be drawn that the required step frictional coefficient(RSFC)exhibited an"M"shaped curve during the foot contacting with the ground and got its maximum and minimum values when MCOB of the subject was at the highest and lowest position respectively.Moreover,the first peak of RSFC decreases firstly and then increases,while the second peak of RSFC increases with the increase of slope inclination at the experimental condition.The position of pivotal point is decided by the relative size of slope inclination and the angle between the plumb line through MCOB and the line from foot to MCOB.

Near-infrared photon propagation in complex knee by Monte-Carlo modeling

It is highly necessary to study the phenomenon of photon migration in the knee joint for the non-invasive near-infrared optical early diagnosis of the osteoarthritis of the knee. We investigate the migration trace and distribution rule of the photons in knee layered structure, which are simulated by the Monte-Carlo modeling. The proportion of photons which collide with bone tissue then migrate out of the muscle tissue and photons directly migrate out of muscle tissue is calculated. For analyzing the signal-to-noise ratio to determine the accurate position of the detector, we perform quantitative evaluations of distribution of photons, as well as qualitative assessments of the distribution of photons.