Applied Mechanics and Materials Vols. 446-447

Abstract: In today’s market, it is no longer sufficient to have better designs than the competition. In order to maximize the product’s market potential, it has to be rapidly produced and made available to the market. To reduce their time-to-market period, manufacturers need to shorten their design and development process. It becomes vital that the design architecture solution is derived faster, which can be handful for complex products like an aircraft with the current geometrical-based approaches due to the plethora of physical alternatives to be considered. On the other hand, the search for design architecture solution from functional requirements is theoretically more effective because functional space is comparatively smaller than physical search space. This allows the design efforts to be more focused and this subsequently saves time, efforts and resources. With this notion, there is a driving motivation to adapt functional approaches into the conceptual product design process in order to exploit some of its advertised benefits. In this paper, an example case study of an aircraft conceptual development is presented to highlight possible advantages of approaching architecture solutions from the functional space.

Abstract: Identification of modal parameters is crucial especially in aerospace applications whereby the interactions of airflow with aircraft structures can result in undesirable structural deformations. This structural deformation can be predicted with knowledge of the modal parameters. This can be achieved through conventional modal testing that requires a known excitation force in order to extract these dynamic properties. This technique can be experimentally complex because of the need for artificial excitation and it also does not represent actual operational condition. The current work presents part of research work that address the practical implementation of operational modal analysis (OMA) applied to a cantilevered hybrid composite plate exposed to low speed airflow in a wind tunnel. A single contactless sensing system via a laser vibrometer is employed to measure the response. OMA technique applied in a wind-on condition succeeded in extracting the modal parameters of the hybrid composite plate which correlate well with modal testing using impact hammer excitation.

Abstract: RLVs' gliding capability, determined by its maximum dive and maximum range, provided a significant restriction in TAEM trajectory planning in this paper. The maximum-dive trajectory was generated based on Eq.(3) for a constant maximum dynamic pressure. In the guidance, it was optimized to be Eq.(13) for the open-loop command of bank angle in HAC segment. The simplified closed-loop command of angle of attack contained errors of altitude and path angle except the controlled velocity. Energy propagating as Eq.(8) calculated the reference velocity for the speed brake to track. Finally, an illustrative example was given to confirm the efficiency of the trajectory planning algorithm and optimized command. The simulation results in Fig.2 and Fig.3 indicate the proposed trajectory planning algorithm and guidance method are useful for the gliding capability limited RLV's TAEM with initial deviations.

Abstract: This paper compares the performance of two newly designed ultrasonic motors. Based on the finite element analysis, it is found that the motor with piezoelectric stack as functioning components can produce much better mechanical output properties.

Abstract: Inlet is one of the basic elements of squirrel cage fan that can have great effect on performance and losses, especially between inlet exit and first section of impeller width. In this paper the effect of axial gap between inlet diffuser and impeller on performance and flow pattern is considered. Three diffuser inlet sizes with respect to impeller size (smaller, nearly same and bigger than inner impeller diameter) and three axial gaps within the available dimensions of the casing and impeller were chosen. Numerical simulations were performed to find the effect of this axial gap on flow pattern, performance and efficiency. From the simulation of each case study, flow pattern and its mechanism and the causes that affecting the efficiency and performance due to axial gap are analyzed and presented.

Abstract: Inlet is one the basic elements of squirrel cage fans that has a significant effect on fan performance and efficiency. Recently using the CFD calculation methods with sufficient related tools for finding the flow pattern and related parameters, applying modifications and representing proper solutions, has being increased. In the present case study to study the effect of inlet diffuser diameter on the fan efficiency and flow pattern, using numerical simulations and experimental validations, three different inlet diffuser diameters are used as inlet instead of inlet nozzle. To simulate these cases some geometries with special additional element, proper mesh pattern and size and proper turbulence model was chosen.It is observed performance and efficiency curves of fans with respect to use of inlet nozzle are more flattened with higher magnitude. So fan operation around the best performance point is more stable without significant fluctuation of head pressure and efficiency.

Abstract: A diffuser leading edge has been designed for aircraft aerosol sampling. The diffuser leading edge fluid was conducted using the CFD. The diffuser inlet, middle and outlet diameter is 35.3, 100 and 35.3 mm, respectively. The angle of the diffuser inlet and outlet is 4°. The diffuser inlet and outlet with leading edge have achieved isokinetic sampling, and have stable flow and pressure distribution. It is suggested that CFD simulation can be useful for improving the optimum the diffuser.

Abstract: The rail flaw detection vehicle which is according to a city rail system construction features has been developed. This vehicle has been used for more than two years and all aspects of the vehicle performance reaches design requirements. The vehicle can meet the demand for rail flaw detection. This paper has introduced the general layout of this vehicle including main technical parameters, the main structure and the rail flaw detection system. Finally, the strength and dynamics calculation of this vehicle has been performed. The results of the calculation are presented and discussed.

Abstract: Removed at authors request

Abstract: Reliability is most important to the CNC machine tools and reliability estimation is a very important part of the reliability which has magnificence to allocate resources and put forward scientific policy. Reliability evaluation of computer numerical control machine tools can use all sorts of effective information to decrease the size of test samples and save the development costs and shorten the production cycle. The paper put forward to use D-S evidence theory and the information of experts system to decrease the uncertainty of the reliability evaluation of computer numerical control machine tools. The results show that the method can effectively decrease the uncertainty of the reliability evaluation of computer numerical control machine tools.