The fatigue limit of 7085 aluminum alloy was tested by four-point bending fatigue test for samples of different sizes and roughness. The results show that the greater the thickness of the specimen, the greater the ultimate fatigue strength of the material. The higher the surface roughness of the sample, the lower the ultimate fatigue strength of the material. The stress analysis and calculation of the specimen show that the dangerous cross section occurs at the position where the indenter contacts the specimen, where the specimen is subjected to the combined action of bending normal stress and shear force. With the increase of the thickness of the specimen, the shear force on the specimen decreases, and the bending normal stress on the specimen increases under the same fatigue limit. And vice versa. The relation between the surface roughness and the radius of curvature of the sample is shown by establishing a simplified model, and then the relationship between the surface roughness and the fatigue ultimate strength of the material is obtained.

After low-velocity impact at the edge, delamination and matrix extrusion occur inside the composite laminates,which will have a serious impact on the safe use and life of the composite laminates. Therefore, it is of practical engineering significance to establish a fatigue life prediction model for low-velocity impact at the edge. The dent damage size, compressive residual strength and fatigue life of the fatigue life prediction model were obtained by low-speed impact test, compression test and compression-compression fatigue test. Based on the average stress failure criterion, the impact damage area of the laminated plate was equivalent to the corresponding aperture by combining the opening equivalent method, and the equivalent damage coefficient of different impact energy was proposed. A fatigue life prediction model considering the compressive residual strength of impact damaged laminates was established, and the prediction results were compared with the test results.The results show that the fatigue life prediction accuracy of the model is high, the error is controlled within 10%, and the model has good prediction ability.

Sprocket chain ring drive system is the core component of scraper conveyors. The wear of sprocket chain socket is one of the main fault of scraper conveyors. Started with the analysis of the meshing transmission characteristics of the sprocket chain socket, constructed the Archard linear wear model, calculated the wear depth of the chain socket’s linear under working conditions, measured the wear depth of the actual wear sprocket, and verified the accuracy of the Archard linear wear model. The deformation model of ring chain was constructed by finite element method, the shape change of chain socket busbar was predicted, and the shape of sprocket tooth surface after wear was reconstructed according to the change of direction and busbar. The influencing factors of chain socket wear were analyzed. The results show that increasing the hardness of sprocket material, reducing the chain speed, the load and the laying angle can reduce the chain wear. This study provides a basis for the study of the wear pattern of sprocket chain of scraper conveyors.

Auxetic materials have garnered attention due to their novel behavior under deformation and numerous other material properties, such as fracture resistance, shear resistance, and energy absorption. By integrating hyperelastic materials with auxetic structures, the highly deformable capability enables the design of structures with enhanced mechanical tunability.To this end, a design methodology for 3D printed auxetic structures with improved mechanical adjustability was proposed. The in-plane compressive behavior of the designed structures was investigated through test and numerical analyses. The results demonstrate that, compared to conventional auxetic structures, the composite material with auxetics structures exhibits higher stiffness and enhanced energy absorption performance. By further adjusting the distribution and amplitude of sinusoidal ligaments, auxetic structures with tunable energy absorption, Poisson ratio, and deformation modes were generated. This study presents a design approach for improving the mechanical properties and energy absorption of lightweight structures.

Aiming at the inaccuracy of the finite element analysis (FEA) of heavy-duty engineering wheels under the radial loading condition, a new simulation analysis model based on the results of wheel-tire contact pressure test was established. Firstly, a stress data corresponding to the wheel under inflation pressure condition alone undergo testing, and a loading model for inflation pressure was formulated using a Gaussian function of 4th order. Secondly, a stress data collected while the wheel experiences combined inflation pressure and radial load were analyzed. The influence of inflation pressure was isolated, allowing for the development of a circumferential loading model and an axial loading model for the radial load,using a Fourier function of 4th order and a sinusoidal function of 4th order, respectively. Finally, the validation of the loading model was conducted through Ansys simulation. The outcomes demonstrate the calculation error of mere-approximately 1. 943% in relation to the measured data for the key calibration points. Additionally, the observed stress distribution manifests a remarkable degree of consistency. This substantiates the accuracy and reliability inherent in the proposed radial contact pressure distribution model.

The calculation of bending strength for spiral bevel gears is complex, making accurate evaluation extremely challenging. Focusing on the two distinct calculation methods, B1 and B2, as outlined in the ISO 10300 standard, this study begins with the computational principles of both approaches. It compares the selection methods and numerical application principles for parameters involved in calculating root bending stress and allowable bending stress under both methods. The influence of parameter values on root bending stress calculations is analyzed for each method. Through computations on multiple design samples, the root bending stress values derived from both methods are compared. Finite element analysis is employed to validate the computational results. The findings indicate that due to differences in the types and values of correction coefficients used, there are certain discrepancies in the bending strength evaluation results obtained by the two methods. Method B1 yields a more conservative evaluation of root bending strength, with root bending stress approximately 5% lower than that calculated by Method B2. Although the ISO calculation standard accounts for load sharing among multiple teeth, it overlooks the combined effects on root bending stress, leading to deviations from finite element analysis results.Method B1 shows closer agreement with finite element results, with an error margin of about 6%.

In order to investigate the stress concentration phenomenon and analyze the distribution characteristics of the interlaminar stress in the hole edge region of composite laminates. Based on the generalized mixed variational principle, the generalized mixed finite element model for laminated plates with various stacking modes were established. The stress field variables were divided into the interlaminar stress and the in-plane stress, with the introduction of stress boundary conditions to ensure the physical continuity of interlaminar stresses between layers and the discontinuity of in-plane stresses between layers.The interlaminar stresses at the edge of the laminated plate hole were respectively analyzed through the thickness direction and the circumferential direction. Numerical examples demonstrated that the incompatible generalized mixed element could obtain more accurate stress singularity results than the 8-node three-dimensional solid incompatible displacement element results solved by the finite element software Abaqus. Stresses on both upper and lower surfaces of the laminated plate consistently reflected actual situations. The research indicates that compared with the displacement element, the incompatible generalized mixed element can more effectively capture the high stress gradient of the interlaminar stresses at the edge of the laminated plate hole, which provides a new idea for the optimal design of the laminate.

Negative Poisson ratio structures are widely applied in various engineering fields due to their excellent mechanical properties. By combining the star-shaped honeycomb structure with the re-entrant structure, a novel re-entrant angle-type negative Poisson ratio honeycomb structure is proposed. Firstly, the unit cell structure was simplified and analyzed based on symmetry, and the analytical expressions for the Poisson ratio and equivalent elasticity modulus of the structure were derived using the energy method. Secondly, the vertical compressive mechanical properties of the structure were investigated using Abaqus finite element software, and the numerical simulation results were compared with the theoretical calculations to validate the accuracy of the analytical expressions. Finally, the influence of different geometric parameters of the unit cell structure on the equivalent Poisson ratio and equivalent elasticity modulus was discussed, and the equivalent mechanical properties of the structure were compared with those of conventional star-shaped honeycomb structures. The results demonstrate that the proposed structure exhibits favorable negative Poisson ratio characteristics, and its equivalent mechanical properties can be adjusted by modifying the geometric parameters. The findings provide valuable insights for the design of novel negative Poisson ratio metamaterials.

Constitutive analysis of steel wire rope conveyor belt is a key problem for conveyor belt design optimization and energy conservation. Maxwell model and Burgers model based on viscoelastic theory and transient dynamics were constructed. Considering the fretting friction damping between steel wires and the mutual damping between steel wire rope and conveyor belt, a mixed constitutive model was constructed. Under the condition of 0-30 ℃, the relationship between the parameters of the constitutive model was established, the simulation curve was fitted and solved by Matlab, and the accuracy of the mixed constitutive model was verified by taking 40 ℃ as the control group. The verification results show that the maximum error between the conveyor belt represented by this constitutive model and the experiment is 5. 88%, demonstrating that this constitutive model can better characterize the rubber conveyor belt with steel wire rope core. The universality of this model is verified by the method of simulation and prediction. It provides a theoretical basis for the structural optimization and energy-saving analysis of conveyor belt.

A theoretical model of composite metal rubber (C-MR) was established on the basis of static mechanical test. A novel preparation process was used to prepare C-MR, which was subjected to static mechanical tests. The mechanical model of C-MR was established by combining the static mechanical models of wove-metal rubber (W-MR) and tangled-metal rubber (T-MR), and the effects of different knitting and winding ratios on the mechanical properties of C-MR were investigated. The comparison between the test data and the theoretical model shows that the theoretical model can predict the mechanical properties of C-MR effectively. The results show that the knitting and winding ratio has a significant effect on the mechanical properties of C-MR, and the larger the knitting and winding ratio is, the larger the stiffness and damping properties of C-MR are. The conclusion can provide a theoretical support for the preparation and application of C-MR.