Applied Mechanics and Materials Vol. 607

Abstract: A method for predicting the vibration characteristics of the short thin-walled cylindrical shell was presented by dynamic similarity analysis. Firstly, the similarity conditions between the prototype system and its complete-similitude scale model were derived from their equations of motion. Then, the scaling factors, such as length, radius, thickness, force, and excitation frequency, spring constant and dynamic responses of the cylindrical shell were determined based on the last similarity conditions and the dimensional analysis theory. Free and forced vibration analyses of the elastically supported prototype cylindrical shell and those of its complete-similitude scale model were performed to validate the derived scaling laws, and satisfactory results were obtained.

Abstract: This paper presents a new approach for reducing energy consumption coupled with force and position controls in the electro-hydraulic systems (EHS). The EHS inverter will be added for control to vary the speed of electric motor driven hydraulic pump. In addition, a single directional control valve is used to control the system parameters, which cause loss of energy. The main objective of this research is to numerically analyze the energy loss in the new control approach in the EHS with the inverter by using a simple directional control valve. The spool displacements of 4/3 hydraulic closed center directional control valve, transient flow-pressure coefficient and energy loss were simulated with computational fluid dynamics (CFD). In addition, this paper presents CFD results. The relationships of flow rate variables with time-dependent pressure drop and energy loss were addressed. The flow behaviors related with transient flow-pressure coefficients were also discussed. It is found that the loss of energy increases, depending on both the large opening spool displacement and the inlet flow variable.

Abstract: Mechanical models have been more on technical rather than on biological concepts, which yield unstable locomotion with low speed. Structural and locomotive characteristics of living creatures are copied and modeled with 13 links, 12 joints and body, from the mechanical engineering viewpoint. Quadruped models are simulated as a time variable for the one cycle. Torques at joints are calculated and finally converted to total consumed energy. Variables, specifying structure and locomotion, are applied to the simulation as a time function, and the optimal variables which minimize energy expenditure are derived which can be directly applied to the Quadruped locomotion.

Abstract: The gear-shaft-bearing-housing coupled finite element model of marine gearbox was established by using the truss element, the spring element and the tetrahedral element. The modal of gearbox was analyzed by using the ANSYS software. Then through the experimental modal analysis, the natural frequencies of gearbox are obtained. Compare the experimental results with the numerical results, it shows good agreement.

Abstract: Finite element model of folding wings was designed in the light of structural scheme, and each part of the model used composites. Different aeroelastic analysis models were built from emission to cruise, and then the models were made the study focus on flutter analysis. The result showed the change relationship of the critical flutter speed of wings and flutter frequency with sweep angle in state of expansion process, and the change relationship of the critical flutter speed of wings and flutter frequency of folding wings with cruising altitude and cruise Mach number in state of cruise. The whole flight state was analyzed if the folding wings might flutter, and if it took place the structure optimization of wings was needed. Simulation results have a certain guiding significance for practical engineering application.

Abstract: Research how to realize real-time hardware in the loop (HIL) of industry design system by utilizing a variety of virtual reality (VR) hardware and software. In this paper, it introduces VR and virtual prototyping technology, and then proposes joint control and simulation based on ADAMS / Aircraft, Simulink, Flightgear three software. Moreover, the virtual scene, data gloves and real-time semi-physical simulation are analyzed and researched; finally as an example, build a real-time semi-physical simulation platform of the landing gear system for multi-wheel and multi-strut aircraft. The system can do kinematic and dynamic analysis, real-time control by visual prototyping and digital models through real-time data acquisition and co-simulation.

Abstract: The static mixers are widely used in many industries to obtain the desired type of mixing. In the context of mixing process, two different fluids and have a different properties will mix in a single equipment to produce an another fluid with a new property. In this research, a new approach of static mixers was proposed for pipeline mixing. The flow pattern, pressure drop and mixing characteristics (coefficient of variation) were carried out by means of computer simulations. The static mixers introduced here consists of a series of perforated plate with circle grids fractal pattern elements. The simulations work were carried out by using a commercial package of Computational Fluid Dynamic (CFD), ANSYS CFX 14.0 software. Three levels of laminar flow with Reynolds numbers (Re) of 100, 200 and 400 respectively had been used to investigate the performance of the static mixers introduced here. The effectiveness of circle grid perforated plate static mixer had been evaluated by comparing the homogeneity level of mixing fluids for each flow simulated. The simulations gave a new insights in the flow pattern in circle grids fractal perforated plate elements. The pressure drop predictions compare favorably with literature data and the coefficient of variation (COV) value for circle grid perforated plate with 50% porosity at Reynolds number 100 was 0.0744 which is out of the range meanwhile at Reynolds number 200 and 400 was 0.0483 and 0.0247 respectively which are in the range of reasonable target for many applications. Mixing in the elements occurs through a combination of flow splitting and shearing at the junctions of successive elements. Besides that, simple installation and manufacturing of this type of static mixers makes the fractal perforated plate’s element an excellent static mixing device.

Abstract: The dynamic characteristics of joint interfaces have significant effect on both static and dynamic behaviors of the whole machine tool structures. A test system for identifying the unit area dynamic characteristic parameters of Fe-based joint interfaces in still and motion states were represented based on Equivalent Single Degree Of Freedom (ESDOF) system theory. Compared with the stiffness and damping parameters in stationary state, the stiffness is reduced and the damping is increased in motion. When the velocity increased, the equivalent stiffness and damping parameters of joint interface are both increased.

Abstract: For the hard and brittle materials like optical glasses, ultra-precision grinding machine is primarily used, which can generate parts with high surface finish, high form accuracy and surface integrity. Motorized spindle is an inevitable choice of ultra-precision machine, but it has a prominent heat problem for its specific configuration of build-in motor. The paper does some research about motorized spindle thermal property. The heat resources and heat transferring ways are analyzed. The temperature distribution and deformation distribution of motorized spindle system are calculated through thermal structure coupling finite element analysis. The analysis results can provide warranty for motorized spindle design.

Abstract: The Braking-force distribution on the left and right wheels is a key factor influencing the braking performance of vehicles at a corner. To promote the braking stability and the control ability at the turning-braking process, a new method based on the steering-angle feedforward control principle was proposed to realize dynamic braking-force distribution on the left and right wheels. A vehicle model of three wheels with two freedom degrees was established. Computer simulation of the turning-braking process with dynamic distribution control was carried out. The simulated results show that the difference between the actual yaw rate and the ideal one is significantly reduced at the period of braking being effective. It is validated that the method can effectively improve the braking stability and the control ability of vehicles at the turning-braking process.