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In order to achieve the change rule of the induced residual stress (RS) field after multipass ultrasonic surface rolling (USR), a mathematical model of the induced residual stress (RS) field after multipass ultrasonic surface rolling is first established. Then, the coupling mechanisms of the RS field after dual-pass USR and multipass USR are analyzed, respectively. Subsequently, a finite element (FE) model is established, and the influence of the interval between two adjacent rolling paths L S is investigated. Finally, both the mathematical model and the FE model are experimentally verified. The results show that both the mathematical model and the FE model can predict the RS field after multipass USR. Two adjacent RS fields will couple with each other in their overlapping regions. For a relatively small interval L S , the RS field after multipass USR can be fully coupled, so as to form a uniform compressive RS layer. In this study, when L S = 0.05 mm, the values of the surface compressive RS, the maximum compressive RS, the depth of the maximum compressive RS, and the depth of the compressive RS layer reach 426.71 MPa, 676.54 MPa, 0.05 mm, and 0.54 mm, respectively. [ABSTRACT FROM AUTHOR]

A flip-flow screen can effectively screen viscous particles, and its kinematic characteristics determine its screening performance. Since previous kinematic models have errors, a novel kinematics model of the flip-flow screen panel, namely the inclined catenary model, is developed. It is verified by comparing theoretical motion trajectory with experimental motion trajectory. Then, the kinematic characteristics, i.e., displacement, velocity and acceleration, obtained using four kinematic models, are compared. Finally, the effects of rotation speed n, eccentricity e, incline angle α and tensional amount Δl on displacement, velocity and acceleration of the midpoint are investigated. The results show that displacement, velocity and acceleration of each point in the screen panel can be calculated by using the inclined catenary model, and the inclined catenary model possesses higher prediction accuracy than the three previous kinematic models. Moreover, with the increase in n, the absolute value of velocity and acceleration increases, and the maximum absolute value of displacement remains unchanged. With the increase in e, the absolute value of displacement, velocity and acceleration increases. With the increase in α, the absolute value of transverse components of displacement, velocity and acceleration increases slowly and the absolute value of longitudinal components of displacement, velocity and acceleration decreases slightly. With the increase in Δl, the absolute value of displacement, velocity and acceleration increases. Therefore, the inclined catenary model can provide good guidance for selecting reasonable screening parameters. [ABSTRACT FROM AUTHOR]

This work aims to achieve the 6000t compression-shear test machine frame design with the lightweight. The force condition of the compression-shear test machine frame under limited working conditions is first analyzed, and the static analysis of the compression-shear test machine frame is performed using ABAQUS. Then, taking the volume of the frame of the compression-shear testing machine as the constraint condition, the topology optimization of the compression-shear testing machine frame is performed using the variable density method of topology optimization, and the model is reconstructed accordingly. Finally, not only the static characteristics of the frame before and after optimization but also the modal characteristics of the frame before and after optimization and the dynamic characteristics after sudden unloading are compared and analyzed. The results show that the weight of the frame decreases by 14.5% after optimization, and the maximum static stress of the frame is still less than the yield strength of the material; the maximum displacement is still less than the allowable maximum displacement, which meets the requirements of static strength and stiffness. The natural frequency of each mode is much greater than the working frequency, which meets the requirements of dynamic stiffness. After sudden unloading, the maximum dynamic stress of beams, columns, and base of the frame are less than the yield strength of materials, which meets the requirements of dynamic strength. [ABSTRACT FROM AUTHOR]

In this paper, the theoretical models of the surface topography and residual stress (RS) were proposed, and the abrasive water jet sequential peening (AWJSP) finite element models were established by using ABAQUS. Then, the formation mechanism of the surface topography in multiple passes AWJSP process and the coupling mechanism of RS in a single and multiple passes AWJSP process were analyzed. After that, the influence of the number of shots (i.e. N), the distance between the center of adjacent shots Dc, shot velocity v, and shot radius R on the surface topography and residual stress field (RSF) of the target were investigated. Results show that successive dimples were formed by single-pass AWJSP, the RSF formed by the impact of each shot will influence the previous RSF, and that will be coupled with it. In multiple passes AWJSP process, decreasing Dc can decrease the surface roughness, the surface smoothness of the target material will gradually become better, and the RSF will also be uniform. Under full coverage condition, the surface roughness Rt and mean width of the profile Rsm will gradually decrease with the decrease of Dc, while the change of Dc has little influence on the RSF. Increasing the v can increase Rt and Rsm, and it is beneficial to induce a large and deep compressive RS layer. Increasing the R can decrease Rt, Rsm remains unchanged, and it is beneficial to induce a deep compressive RS layer. [ABSTRACT FROM AUTHOR]

This article reveals the formation mechanism of surface topography and the formation and coupling mechanism of residual stress field (RSF) after abrasive water jet sequential peening (AWJSP) that can sequential peening on the material surface at a certain distance interval, and proposes a mathematical model of surface dimple characteristic verified by simulation results. In addition, the influences of shot velocity v0, shot radius R and the distance between the center of adjacent shots DC on surface topography and RSF were also investigated. Results show the surface dimple forms resulting from the material plastic strain, and the residual stress (RS) is mainly induced by the unrecovered elastic strain resulting from the hindering of plastic strain. Decreasing v0, R or DC can decrease the surface roughness Rt, while increasing v0 and R is beneficial to induce a large and deep compressive RS layer. DC influences the whole distribution of compressive RS layer directly. [ABSTRACT FROM AUTHOR]

Water jet peening (WJP) is used to improve the fatigue life of materials by inducing compressive residual stress (RS) into the metal surface. In this paper, the formation mechanism of RS in a single pass WJP process and the coupling mechanism in the multiple passes WJP process are investigated. Then, simulations of single pass WJP are conducted to observe the transient evolution and steady distribution of RS. After that, the influences of process parameters (i.e., the distance between the center of adjacent water jets DC and jet velocity v) on the RS and surface roughness Ra are experimentally and numerically investigated after multiple passes WJP. Besides, the relationship between microhardness and plastic strain is also investigated. Finally, the fatigue performance is evaluated by the tension-tension fatigue tests. Results show that RS is mainly induced by the unrecovered elastic strain resulting from the obstruction of plastic strain. The value of the compressive RS, the depth of the compressive RS layer, and Ra all increase with an increase in v. The distribution of RS and the value of Ra will be affected by DC, the residual stress field (RSF) is uniform, and Ra is minimum for DC = 0.15 mm in this work. Taking RS and Ra into consideration, the optimal process parameters of v = 345 m s−1, DC = 0.15 mm, and jet traverse velocity vf = 4000 mm min−1 are eventually determined. Under this condition, the maximum compressive RS is − 156.7 MPa, the depth of the compressive RS layer is 220 μm, the surface microhardness is 106.7 HV0.1, and the Ra is 0.574 μm. Compared with the original specimens, the fatigue life of the peened specimens and the polished specimens after peening (Ra = 0.382 μm) increased by 53.2% and 90.8%, respectively. [ABSTRACT FROM AUTHOR]

A new method for fabricating CCMPMPs, namely multi-cutter milling, is proposed and the fabrication principle is discussed. Then, a study of three microchannel parameters, the microchannel depthHc, widthWc, and intervalWs, and two CCMPMP parameters, the porosityPand the total surface area per unit volumeSV, is presented. Furthermore, 3D FEM has been adopted to study the effective stress distribution, the metal flow velocity distribution, and the cutting forces. The results show that CCMPMPs can be successfully machined.Hc,Wc, andWscan be controlled by the radial depth of cutae, the slotting cutter thicknessEt, and the gasket thicknessEg, whilePandSVcan be changed by adjustingHc,Wc, andWs. Moreover, asaeincreases, the average resultant force increases, and the friction between chip and the side face of the machined microchannel, and between chip and the rake face, plays an increasingly important role in it. [ABSTRACT FROM PUBLISHER]

A novel peripheral milling process with an end milling cutter for manufacturing aluminum fibers is proposed. Most of the cutting is done by the peripheral teeth of the cutter and the chips removed by the teeth form aluminum fibers, while the cutter end has little effect on aluminum fibers. The machining principle and the formation mechanism of aluminum fiber cross-section are presented. The feasibility of this new fabrication process is experimentally investigated under different machining conditions. In addition, influences of cutting parameters on the equivalent diameter, the length, and surface morphology of aluminum fibers are analyzed. Experimental results indicate that aluminum fibers can be successfully manufactured by peripheral milling and the productivity can be improved by increasing the rotational speed n. Smaller radial depth of cut ae, larger rotational speed n, and smaller feed speedvf are in favor of obtaining slim aluminum fibers. The length of aluminum fibers is theoretically determined by the axial depth of cut ap and also actually affected by other cutting parameters. Of all the cutting parameters considered in these experiments, the optimum parameters of ae, n, and vf are 0.3 mm, 118 r/min, and 60 mm/min, respectively. [ABSTRACT FROM AUTHOR]

The water jet peening (WJP) technology can induce compressive residual stress (RS) in metal surfaces and, thus, improve the fatigue life of components. In this paper, a mathematical model is proposed for calculating the RS induced by WJP. To validate the proposed mathematical model, experimental and finite element simulation verifications were carried out on Al6061-T6. The distribution of RS along the depth direction, the maximum compressive RS, and the depth of the compressive RS layer were also investigated based on the mathematical model. Results showed that the error of maximum compressive RS between the mathematical model and experiment was within 9% under a jet pressure of 60 MPa, and the error of depth of the compressive RS layer between the mathematical model and experiment was within 13% under a jet diameter of 0.3 mm. Hence, the mathematical model is reliable and accurate. The maximum compressive RS increases with the increase in jet pressure, and the depth of the compressive RS layer approximately linearly increases with the increase in jet diameter. [ABSTRACT FROM AUTHOR]