Applied Mechanics and Materials Vols. 117-119

Abstract: Surface roughness plays an important role in product quality and has received serious attention for many years. It has formulated an important design feature in many situations such as parts subject to fatigue loads、precision fits、fastener holes and aesthetic requirements. In addition to tolerances, surface roughness imposes one of the most critical constraints for the selection of machines and cutting parameters in process planning. This paper focuses on developing a geometric model of turn-milling process in order to predict the surface roughness effectively so that we can offer reference or consulting in the practical machining process. The surface roughness model takes into account both cutting parameters and movement parameters such as cutter radius feed per tooth 、 cutting speed 、number of teeth 、cutters' eccentricity、 depth of cutting、spindle rotating speed and so on. Through this model, we discussed the influencing effects of various cutting parameters on the surface roughness and analyze which one has the most important impact.

Abstract: A 3D elastic-plastic and coupled thermo-mechanical FE model for friction stir welding(FSW) of 7075 aluminum alloy plate was developed based on the dynamic explicit code ABAQUS/explicit, then the FSW process of 7075 aluminum alloy plate was simulated and the materials flow behavior was analyzed. The results show that in the horizontal direction of the plate, two patterns of materials migration are produced: (1) the material rotates with the tool and finally deposits the tentative cavity behind the pin; (2) the material transfers in the mode of laminar flow. Furthermore, the streamlines of material in advanced side (AS) are bent along the reverse welding direction. After bypassing the pin, the material of retreating side (RS) moves backward it, and extends to AS.

Abstract: With the improvement of people's awareness of the living environment, there is an increasing need for comfortable residence surroundings, and they begin to re-examine the elements of residence quality and residence comfort. From the perspective of the psychological needs of people's behavior, this article expounds residence's natural and cultural environment, traffic organization, layout design, sothat in designing residence people’s needs and comfort requirements are put in the priority, thus constantly improving the dwelling quality.

Abstract: Rubber waveform generators are widely used in impact test devices for generating shock waves. Through stretching and compressing rubber specimens, obtain the stress-strain relationship of rubber material. Build finite element model of rubber waveform generator, get the maximum static deformation and static stiffness in different forms of constitutive models and take actual tests of rubber waveform generator. Compare finite element results with the actual test results, select Arruda-Boyce model as rubber hyperelastic model. This study lay a good foundation for the design of rubber waveform generators and study of dynamic characteristics of impact test devices.

Abstract: Abstract: In order to control the thermal stress of cladding, a numerical simulation of temperature field during multi-track & multi-layer laser metal deposition (LMD) process is developed with ABAQUS based on “element birth and death” technology of FEM. The dynamic variances of temperature field and stress field of forming process are calculated with the energy compensation of interaction between molten pool-powder. The temperature field, temperature gradient, thermal stress field and distribution of residual stress are obtained. The results indicate that although the nodes on different layers are activated at different time, their temperature variations are similar. The temperature gradients of samples are larger near the molten pool area and mainly along z-direction.

Abstract: The Three-Gorges Reservoir area is characterized by widely distributed strata of Badong Formation, in which large size landslide and deep-reaching loose geological body are likely to form. Therefore, it is significant to reveal the mechanism and patterns of the large size landslide in Badong Formation for better understanding of the development of the nature of deformation and process of formation of the deep-reaching loose stratum slope. In this paper, the geological characteristics of the rock mass of the Badong Formation are concluded on the basis of systematic explanation of the space variation of the lithology combinations and space variation of structural deformation of the Badong Formation in the Three-Gorges Reservoir area. To demonstrate the basic law of long-term deformation of the Badong Formation slopes and the patterns of later stage reform and landslide evolution, the authors exemplify the Huangtupo landslide that is typical in the Badong Formation.

Abstract: Static stents is the switch component that plays the role of fixing and supporting. It will received impact, the attrition and reverse function in the work process, which requires high mechanical properties to meet their work requirements. This paper uses the forming technology of "the pre-formation +warm extrusion + cold finishing "to form the static support ,and it carries on the numerical simulation and optimization analysis, which not only improve the work piece performance greatly and reduce the manufacturing cost.

Abstract: Nitriding is one of the most efficient methods used to enhance the service life of aluminum extrusion dies. In this paper, a new nitriding process has been introduced that is characterized by that 4Cr5MoSiV1 steel, a typical material used for extrusion dies, was nitrided by using two-stage nitriding process. The microstructures of nitrided layer have been analyzed by means of optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and microhardness (MH). The results show that pre-heat treatment on the 4Cr5MoSiV1 steel extrusion die can be carried out under the condition of quenching at 1040 °C, double tempering at 600 °C and 560 °C for 2 hours each. Operating parameters of two-stage nitriding are set as follow: stage one, 520 °C for 6 hours, the flow rate of NH₃ of 0.6 m³/h; nitriding pressure of 453 Pa and stage two, 580 °C for 8 hours, the flow rate of NH₃ of 0.35 m³/h; nitriding pressure of 453 Pa.

Abstract: Cold expansion is a well-known technique for improving the fatigue life of fastener holes in aeronautical structures by introducing a compressive residual stress field around them. In this paper, a 3-D finite element model is used to analyze the residual stress distribution and relaxation around an expanded hole for aluminum alloy 7050. The results reveal that the cutting process of split sleeve cold expansion and creep are main reason for residual stress relaxation in room temperature, which may limit the beneficial effects of cold expansion.

Abstract: One-step spray welding process was used to deposit Ni60 Ni-based self-fluxing alloy coating on 35CrMo wedge disc. According to different microstructure characters the cross-section of spray-welded specimen can be divided into three areas: spray welded coating, transition region and base metal. For the influence of welding thermo, base metal shows pearlite area, incomplete recrystallized area and original pearlite+ferrite area, the hardness of which is between 200HV to 165HV. The hardness of coating is about 865HV, which ensure good wear resistance. Because of the particles incomplete packing and the viscidity of melted metal, micro cavities formed near transition region and combine to form cavity chains, which will decrease the wear resistance and corrosion resistance of coating.