Applied Mechanics and Materials Vols. 433-435

Abstract: AISI 304 stainless steel powder and Al₂O₃ powder was used to produce laser cladding composite coatings in order to improve the surface wear resistance of 45 steel. Microstructure of the composite coating was examined and analyzed by metallographic microscope. Microhardness and wear resistance of the composite under different scanning velocities were evaluated. The results show that the composite coating is composed of planar crystal, cellular crystal, dendritic crystal and fine equiaxed; the composite coatings under different technological parameters are made of the same phases, ferrite (α) and austenite (γ) phases. Microhardness of the composite is enhanced along with the increase of scanning velocity; effect of scanning velocity on wear loss of the composite coatings is not significant.

Abstract: Due to the problem of the mutual interaction between the polishing tool system and the control of poses and positions, it is difficult to hybrid-synchronizationally control the polishing force, the posture of polishing tool head and the polishing trajectory. So the article designed a set of compliant tools that take the pneumatic servo system as the control system, which was used for active polishing aspheric surface of Robot. It was to accomplish the Robots self-adaptive control to the posture of the polishing tool as well as to figure out the correlation of the contact deformation between the polishing tool and the work piece surface, which makes a theoretical analysis on dynamic and steady characteristics of the contact deformation of the tool system. It applied the meek and polishing tools to the polishing processing of the rough machining of large aspheric surface samples to obtain the data. According to the statistics, the polishing tools can effectively solve the problem of the mutual interaction between the polishing tool system and the control of poses and positions. It also owns good adaptive ability and its machining aspheric surface quality can achieve nanoscale.

Abstract: Based on the understanding of material characteristics and interaction between projectile and target, a lightweight hybrid composite armor target consisting of alumina ceramics pellets and ultrahigh molecular weight polyethylene (UHMWPE) was designed and prepared. The target areal density of the armor panel was 7.5 g/cm². The standard size of the armor panel was 150mm×150mm×43mm. The Ballistic Performance of Alumina/UHMWPE composite armor against an impact of 12.7 mm armor piercing (AP) projectile was investigated at the nominal velocity of 818 m/s. The energy absorbing mechanism revealed that the armor was able to protect against the projectile, together with weight saving.

Abstract: Cutting tool will arises the hot transmutation in the process of high-speed rotation, in the paper we use the non-contact image acquisition processing system to fix the position of the cutter blade edge basis on the center of gravity method and quadratic curve fitting, this method get rid of disadvantages of traditional contact measurement, have the advantages of high accuracy and calculation simple.

Abstract: Heat-resistant aluminum alloy because of its low density, low price, good heat resistance and corrosion resistance, has been widely used in aviation, aerospace, weapons and other industrial fields. In this paper, preparation of Al-Fe-V-Si heat-resistant aluminum alloy materials is used in the RS/PM process, and studied the influence law of effect of alloy composition on the microstructure and mechanical properties of heat-resistant aluminum alloy. The results show that, Fe, V, Si element content and Fe/V ratio has great effect on the microstructure and mechanical properties. When the Fe content is too low, the content of Al₁₂(Fe, V)₃Si phase is less. Mechanics to improve material properties cannot be maximum; if the content of Fe is excessive, the strength of the material do not increase, but decrease the plastic. The addition of V element can be stabilized in Al₁₂(Fe, V)₃Si Si phase; and the addition of Si can inhibit the second-phase dispersion phase coarsening and decomposition, increase the high temperature stability of materials; Fe/V ratio affects the coarsening rate of second-phase particles, thus affecting the thermal stability of materials.

Abstract: A simple FGM object with one gradient direction is easily fabricated by the current technique; However, how to fabricate multiple gradients FGM objects is rarely mentioned by some related papers. This paper proposed a representation and fabrication approach to deal with this problem. This approach, termed as minimum fabrication cell (MFC) or allowance fabrication cell (AFC), focus on fabrication of multiple gradients FGM object. In MFC, an arbitrary 3-D model is adaptively sliced into a series of 2-D layers, and each layer is subdivided into a series of MFC or AFC along toolpath. The three linear interpolation is applied to calculate the material for each MFC or AFC, and gradient contribution ratio (GCR) is applied to calculate the material for each vertex on the MFC or AFC.

Abstract: High strength aluminum alloy is mainly traditional alloy hypoeutectic composition, containing the solid solubility of alloy elements atomic fraction is greater than 2, and reached the alloy trengthening effect by the precipitation of intermetallic compounds in the process of aging. But in more than 150°C, the precipitated phases coarsening, the material performance dramatically, thus limiting its use scope. In the preparation process, the planar flow casting process will melt thrown by 35-80um thick slices with, because the cooling speed can reach 10⁵K/s the process of melt, so the microstructure is very fine, after extrusion. Grain size of about 1um, precipitates spherical and uniform distribution, the size of about 50nm, Al₁₂(Fe,V)₃Si phase coarsening rate is low, so the alloy has comprehensive mechanical performance and excellent high temperature stability.

Abstract: In this paper, the humidity of building materials were controlled by adopting the inorganic salts saturated solutions, and the radon exhalation rate of building materials were measured by the active carbon method which under the different humidity conditions. The result indicates that with the humidity increasing, the radon exhalation rate of building material first increasing and then decreasing; The average roundish radius of building material bigger, the speed of radon releasing coefficient arrival the saturation point was quicker; the porosity and humidity was bigger, the radon diffusion coefficient descended was quicker. Under the relative humidity of 56%-96%, the active carbon box with diffusion base may effectively reduce the influence of humidity on active carbons radon absorption, but under the relative humidity of 56%, the active carbon box with diffusion base may not affect the humidity to active carbons radon absorption.

Abstract: Bobbin tool friction stir welding is a new type of friction stir welding. In the study, the thermo-mechanical model of the bobbin tool friction stir welding was set up. By this model, the temperature field of AA 2014 aluminium alloy work plate of 6mm was simulated, which provides useful information for the investigation of this new process. Simulation results show that the temperature field of the cross section presents symmetry approximately about the mid thickness of the work plate. The high temperature zone has large radius at bottom and top surfaces near the shoulders while small radius at the mid thickness, like a waist. The max temperature for the point at retreating side is about 40°C higher than advancing side.

Abstract: Rubber sealing ring is one of the common seal components of military products, and its performance will directly affects the storage life of ammunition. There are many factors influencing the sealing ring storage life, so it is not easy to give the exactly life for one specific model of sealing ring. By taking one O type sealing ring as the research object for the accelerated ageing test, we can get the degradation data on different temperature and the relationship between the O-ring's pseudo storage life and storage temperature based on each specimen's property's degradation trajectory equation. And in the end, we predict the storage life for O-ring in normal temperature.