Applied Mechanics and Materials Vol. 151

Abstract: As one kind of mechanical static structure symmetry, glide symmetry is grouped by mirror symmetry and translation symmetry. Glide symmetry is widely exists in mechanical systems, and plays an important role in realizing the technical, economic and social performances of mechanical products. On the basis of research on the concept systems of mirror symmetry, translation symmetry and glide symmetric instances, and taking the characters of the different combined types of symmetry benchmarks as the standard, the concept system of mechanical glide symmetry was established, which can be the foundation of further researches on the application laws of glide symmetry in mechanical systems.

Abstract: Rotation-translation symmetry is grouped by rotation symmetry and translation symmetry, and is a common kind of structure in transmission mechanism, change mechanism, transport mechanism, supply mechanism and so on. Based on the research on a lot of instances, and referring the concept systems of rotation symmetry and translation symmetry, the concept system of mechanical rotation-translation symmetry was established by taking the difference of symmetry benchmarks, the directivity and the alternations of symmetry components as standards. Accurate instances were used for explaining and verifying the concept system. The further researches on the application laws of rotation-translation symmetry can benefit from this result.

Abstract: The wear resistance of coated tool can be predicted widely by experiments and theoretical analysis. In the paper, an unique method is adopted to analyze influence of high speed on key stresses of the coated tool .First, through the cutting process simulation with different high cutting speeds, contact stress, shear stress and temperature distribution of the surface of the coated tool can be obtained when the cutting process is steady. Then the stresses and temperature are applied to the coated tool to analyze the key stresses in the tool. The result shows the potential failure of coated tool can be predicted by Finite element analysis correctly. Crack between coating and substrate may occur at the same position with different cutting speeds.

Abstract: Abstract: Researched Chebyshev equiripple approximation FIR filter theory. In the algorithm process, we adopt direct remez algorithm, by a recursive formula to calculate the filter coefficients directly. Combined TMS320VC5502, we designed software and hardware system of Chebyshev equiripple band-pass filter to realize the voice signal filtering. In hardware system TLC320AC01 complete A/D and D/A converter, TMS320VC5502 complete data processing and filtering.

Abstract: With the rapid development of hydraulic technology, pressure-driven piston pump, the output pressure, simple structure, in the field of mechanical engineering and field engineering work has been widely used. For existing pneumatic piston existence of a functional insufficiency, poor technical performance, the irrational structure, and high-pressure areas, especially in high pressure areas occupy an irreplaceable position in the axial and radial piston pumps, there are also complex, expensive, traffic pulse rate not ideal and other indicators of disadvantage. In this paper, the normal replacement method for flexible-rigid pneumatic cylinder replacement tendons, structural design, light weight, is able to adapt to harsh environments tendon type pneumatic piston. Practical results shows that the design of the pneumatic piston in the wild-type tendon in applied engineering work obtains good results.

Abstract: Few literatures employ SIFT (scale-invariant feature transform) for tracking because it is time-consuming. However, we found that SIFT can be adapted to real-time tracking by employing it on a subarea of the whole image. In this paper the particle filter based method exploits SIFT features to handle challenging scenarios such as partial occlusions, scale variations and moderate deformations. As proposed in our method, not a brute-force feature extraction in the whole image, we firstly extract SIFT keypoints in the object search region only for once, through matching SIFT features between object search region and object template, the number of matched keypoints is obtained, which is utilized to compute the particle weights. Finally, we can obtain an optimal estimate to object location by the particle filter framework. Comparative experiments with quantitative evaluations are provided, which indicate that the proposed method is both robust and faster.

Abstract: With the rapid development of science and technology, Lathe will be sure to develop in the direction of high speed, high precision and high stability as the most basic and important production equipment in industry. The spindle is the one of important component in the lathe, of which static and dynamic characteristics is directly related to the machining precision and machining stability, and the performance of spindle system directly affects the overall machine specifications. Through the analysis of the characteristics of spindle, the ways and means of the spindle analysis are studied. For the requirements of static and dynamic characteristics analysis in the process of spindle design on high-precise CNC lathes hydrostatic, direct-drive spindle motor mode is used. Three-supporting structure is adapted in the layout of spindle bearing in order to improve the accuracy and stability of the spindle drive. The rolling bearing is used in auxiliary support, the front and rear radial bearing is used in master hydrostatic bearing. Thrust bearings are located on both sides of the former type of radial bearing to complete the selection of the spindle material and the design of the structural primary dimensions. It is meaningful to improve the specifications of CNC lathes, guide the design, generation and modification of the high precise CNC lathe and enhance static dynamic characteristics of the spindle and improve accuracy and stability of the machine tool processing.

Abstract: Considering the thermally-growth oxide (TGO) that grows between top ceramic coating (TCC)and bond coat (BC) interface and surface morphology of bond coat in a TBC system, the effect of residual stresses distribution by actual and assuming interface morphology in TGO area was calculated with ABAQUS. The calculating result shows that the residual stress of TCC/TGO and TGO/TCC interface are affected by interface morphology obviously, σ_yy is tensile at peaks and compressive at valleys for both with maximum stress beside the symmetrical center and at the symmetrical center respectively. σ_yy stress in TCC is bigger than that of BC for both. σ_xx stress of actual TGO in the three layers remains the same, the interim area change dramatically with TCC layer compressive stress, TGO layer smaller compressive stress, BC layer tensile stress.

Abstract: In order to investigate influence of aggregates on cracking resistance of concrete at early age, four kinds of aggregates, i.e. syenite, basalt, marble and sandstone, were used for the test on cracking resistance of hydraulic concretes by the temperature stress testing machine. Analogy analysis was carried out with test results of concretes with two gradings of aggregates. The results show that aggregates affect elastic modulus, thermal expansion coefficients and tensile creep behavior of concrete at early age. However, the temperature rise of concrete was slightly affected by various types and gradings of aggregate. Moreover, the cracking temperature is reliably to be used to quantitatively evaluate the influence of aggregates on cracking resistance of concrete at early age.

Abstract: At present, the great efforts Robot or the robotic arm of the smaller volume urgently needs to be researched and developed. Designed a new smaller volume heavy articulated Robotic arm test system of combination servo drive, created the mathematical models of the system, done the numerical simulation and PID optimulition of the system based on the MATLAB software platform. Simulation results show that, according to the synchronized control and PID optimization, this system has the advantages both of high positioning accuracy for motor drive system and of strong driving capability for hydraulic drive system， it showed high tracking accuracy and high speed of response for the input signal of large load, and has realized a combination servo drive of a smaller volume heavy articulated robotic arm of fast high-precision.