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.

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.

The subsurface damage depth of grinding WC-10Co-4Cr coating with a cup wheel was investigated in an effort to address the issue that the subsurface damage will cause the coating's performance to deteriorate. The theoretical formula of single particle grinding force was obtained based on the principles of indentation fracture mechanics and grinding material removal theory. A theoretical subsurface damage depth prediction model was developed based on the cup wheel's surface grinding properties. The design of the single factor surface grinding test and the single point polishing test was to confirm the model's accuracy. Analysis was done on how various grinding parameters affected the workpiece's surface roughness and depth of subsurface damage. The maximum relative error is 15. 8%, and the predicted subsurface damage depth agrees with the measured value, according to the results. Surface roughness and subsurface damage depth rise with feed speed and grinding depth, but fall with spindle speed. The study has some theoretical significance for directing the process parameter optimization of cup wheel grinding of WC-10Co-4Cr coatings.

As a common material for flow components, 17-4PH(0Cr17Ni4Cu4Nb) martensitic stainless steel is vulnerable to serious cavitation damage. Based on the corrosion inhibition effect of array texture structure，this study focused on the cavitation characteristics and inhibition mechanism of 17-4PH material under the surface structure of hundred-micron groove array. Based on the ultrasonic cavitation test platform, the experimental data were obtained by the weight loss method, and the data points were fitted by Logistic equation to obtain the nominal incubation period and other parameters. The results show that the surface groove target with groove spacing W and groove width L in the range of hundred-micron has a good inhibitory effect on cavitation damage. The geometric parameters of the groove array structure with the appropriate ratio can further reduce the cavitation damage of the material. The groove array target with groove width L=700 μm and groove spacing W=400 μm has the longest incubation period (22. 79 h) and the smallest cumulative mass loss (10.92 mg) after continuous cavitation for 50 h, thereby exhibiting the best cavitation resistance. This study can provide reference for practical engineering applications in preventing cavitation erosion.

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.

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.

The disc spring will bear the cyclic displacement load during using, resulting in the fatigue damage and the stiffness degradation of the disc spring, which causes irreversible influence on the compensation function when accumulated sufficiently to cause fracture. Therefore, the disc spring material which occurred internal fatigue and structural stiffness degradation was studied under the cyclic load. By considering characteristics of the geometric nonlinearity and the action of the cyclic load, based on the traditional stiffness degradation model, a stiffness degradation model fitting for disc springs was established. The force change of the structural system, the law of stiffness degradation of the disc spring, and the stiffness degradation model were analyzed and verified with the finite element software. The model was modified based on the test data to obtain the model that can be used to calculate the degradation of the disc spring stiffness. This model can predict the deformation of disc springs’ structure in service, and determine the fatigue damage and performance degradation degree,which can provide some basis and reference for the application of disc springs.

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.

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.

Aiming at the vibration fatigue problem of the battery box of electric vehicles, based on the test loads in the real vehicle test field, the fatigue performance of the battery box was compared and analyzed based on single-axis and multi-axis (sequential loading, coupled loading) vibration loads. Firstly, the three-directional acceleration loads were collected at the sensitive points on the battery box in the test field. The power spectral densities were fitted and compared in the same direction of the loads at different measurement points respectively, and the power spectral densities were accelerated through the frequency-domain damage equivalence method to obtain the distribution characteristics of the random vibration three-directional acceleration power spectral densities under the test field specification. Secondly, based on the theory of random vibration fatigue analysis, the multi-axis sequential excitation and multi-axis coupled excitation of the battery box were constructed. Based on fatigue damage equivalence, a uniaxial strengthening spectrum excitation was constructed. Finally, the fatigue damage of the battery box under three kinds of excitation was compared and analyzed by the numerical simulation.The results show that the damage locations of the battery box are consistent under the three excitations. The damage under multi-axis coupled excitation is greater than that under multi-axis sequential excitation, and the single-axis enhancement spectrum has a better reproduction effect on the multi-axis coupled damage. This can provide guidance for conducting rapid vibration fatigue tests of battery boxes based on uniaxial enhanced load spectra.