Rolling resistance (RR) is a key factor affecting vehicle energy efficiency and fuel consumption, and it is strongly influenced by tire design parameters. In this study, the effects of tire mass and key geometric parameters, including dynamic sidewall, dynamic diameter, and seated width, on RR are systematically investigated through experimental measurements and analytical modeling. Unlike conventional studies that primarily focus on applied load, this work emphasizes the influence of the tire's intrinsic mass and incorporates multiple design parameters within a unified framework. To better represent tire behavior under rolling conditions, dynamic (functional) geometric parameters are used instead of nominal values. Based on experimental data obtained under controlled conditions in accordance with ISO 28580, individual relationships between each parameter and RR are established using curve-fitting techniques. A comprehensive model is then developed by combining these effects through different weighting approaches. In particular, a novel sliding normalization model (MSN) is proposed to adaptively determine variable weighting coefficients. Unlike constant and sigmoid-based methods, the MSN approach adjusts parameter weights based on their normalized positions within the dataset range, thereby improving flexibility and predictive performance. The proposed model is validated using 27 tire samples, including 21 test tires and 6 additional tires not used in model calibration. The results show that the MSN approach achieves a lower prediction error than conventional weighting methods. The model demonstrates strong predictive capability within the investigated parameter ranges. It should be noted that the proposed framework is semi-empirical and is developed under controlled testing conditions, with operational variables such as inflation pressure, temperature, and velocity kept constant. Therefore, the model's applicability beyond the studied domain requires further investigation. Nevertheless, the present study provides a practical, adaptable approach for analyzing the influence of tire design parameters on RR and lays a foundation for future model development.
This paper proposes a ceramic ball/nylon elastomer composite structure. Experimental testing and finite element analysis were conducted to investigate the influence of key factors on the penetration resistance of the composite structures with constant total thickness. These factors include ceramic ball diameter, arrangement pattern, projectile head configuration, and the ratio of projectile diameter to ceramic ball diameter. The results indicate that the composite structures with three configurations exhibit higher resistance to round-nose projectiles compared to flat-nose projectiles. For projectiles with a diameter of 8.08 mm (both round-nose and flat-nose), the composite structures with two-different-diameters ceramic balls exhibit better penetration resistance compared to those with single-diameter or triple-different-diameters ceramic balls. Furthermore, when the diameter ratio of the projectile to the front-layer ceramic balls falls within 0.73-1.01, the penetration resistance performance of the composite structure is relatively better, and optimal penetration resistance is achieved when the diameter ratio between the front-layer ceramic balls and other back-layer ceramic balls is 1.7-2.0. These findings provide valuable references for designing penetration-resistant protective structures for ships and other marine constructions.
An improved model for assessing the material properties of porous sigmoid functionally graded (S-FGM) conical shells is introduced. Governing equations are derived within thin-shell theory, incorporating static hydraulic pressure, axial periodic loading, and a Winkler-Pasternak foundation. Critical frequencies and unstable regions are obtained via the Galerkin and Bolotin methods. Parametric studies show that the critical frequency decreases with higher porosity, half-vertex angle, or radius-thickness ratio, but increases with ceramic content or foundation stiffness. Porosity fraction and static axial loading notably affect instability regions, while hydraulic pressure has a negligible effect.
This paper experimentally determines an electric motor driving torque for a steer-by-wire (SBW) system hand wheel actuator (HWA). An equivalent electric motor driving torque for an SBW system HWA is determined with an objective to mirror the steering wheel angular position trajectory of an electric power steering (EPS) system by iterative examination of steering wheel trajectories of the SBW system HWA obtained for a series of driving torques against those from a reference EPS. The objective function criteria are defined by a maximum value of a mean relative error of the steering wheel angular position.
In many practical mechanical systems, the dynamic response is strongly influenced by timevarying stiffness, often coupled with nonlinear damping effects. Neglecting stiffness variability may lead to inaccurate predictions of vibration amplitudes and energy dissipation. This study is the first to extend and apply the stabilized layers method for nonlinear (SLMnl) damping identification to mechanical systems with time-varying stiffness. The SLMnl,kv is developed for multi-degree-offreedom systems exhibiting nonlinear damping and time-varying stiffness. The effectiveness of the proposed method is demonstrated through its application to a spur gear pair system characterized by nonlinear damping and time-varying mesh stiffness.
The research article deals with the study of a thermoelastic double porosity layer of width h with an internal heat source overlying an elastic halfspace. The equations of motion are solved analytically to obtain the expressions of displacement, stress, temperature distribution and pressure in macro and micro pores. The analytical results are then complemented with a numerical example to show the variation of these quantities with horizontal distance. The effect of width of the layer and internal heat source on the quantities is shown by the graphical representations.
In this paper, the losses of kinetic energy in big band saw machines are examined. Expressions have been obtained to calculate the kinetic energy of the mechanical system in the ideal and the real case. With the help of these expressions, the final dependencies for determining the energy losses for the studied class of machines were obtained. These dependences show the influence of linear and angular inaccuracies, i.e. of the parameters e and alpha. A number of optimization solutions have been proposed that allow the values of both parameters to be calculated so that energy losses are minimal. The proposed approach can be used in the design of other classes of woodworking machines, as well as in the study of energy losses for this class of machines.
This study analyzes the influence of finite-length effects on thermally induced flow in a rarefied monatomic gas between two stationary coaxial cylinders. Using the Direct Simulation Monte Carlo method, thermoacoustic waves induced by a sudden inner-cylinder temperature shock are examined under four axial boundary conditions: diffuse, adiabatic, symmetric, and periodic. Results reveal a transient regime, where thermoacoustic waves propagate and reflect depending on boundary type, and a steady-state regime, where temperature, density, and velocity profiles stabilize. Axial boundaries significantly affect wave dynamics, dissipation, and flow structure, particularly at intermediate and radial positions. The findings emphasize the importance of accurate boundary modeling in rarefied gas dynamics for applications in microscale devices, vacuum systems, and aerospace technologies.
In the present paper, a closed form solution of transverse Stokes rarefied slip fluid flow past axially symmetric bodies is being considered. The transverse Stokes drag is evaluated for axially symmetric bodies in the slip-flow regime and which is valid for Knudsen numbers, Kn <= 0.1. The extension of Stokes drag on micro-axially symmetric particles from no-slip boundary conditions to slip boundary conditions has been given. It has been concluded in the end that transverse Stokes drag on the micro-axially symmetric particles is equivalent to Stokes solution for continuum flows multiplied by a rarefaction coefficient which is dependent upon the Knudsen number. The author proposed a new approach of providing analytic closed form drag formula for transverse Stokes slip flow past axially symmetric bodies for rarefied gas.
Coastal vegetation provides critical wave attenuation for shoreline protection, but existing models are computationally prohibitive or lack educational transparency. We present wave-attenuation-1d, an open-source Python package implementing linearized shallow water equations with vegetation-induced drag. The model uses fourth-order Runge-Kutta integration on a staggered grid, achieving unconditional stability through implicit treatment of the drag term. Numerical experiments with monochromatic waves through 40-meter vegetation patches demonstrate transmission coefficients from 0.655 (sparse) to 0.010 (dense vegetation), corresponding to 34.5% and 99.0% wave height reductions. While the one-dimensional framework simplifies threedimensional flows and flexible vegetation dynamics, it provides a computationally efficient baseline for understanding wave-vegetation interactions. The package features standardized NetCDF output and modular architecture, bridging research-grade simulations and accessible educational tools for exploring nature-based coastal protection solutions.
The problem under consideration involves identifying the coefficients of a partial sum of a Fourier series used to approximate the effect of an external periodic force on a Lienard oscillator. A method for constructing a nonlinear identifier is proposed, enabling the real-time asymptotical estimation of the oscillator velocity and coefficients of a partial sum of a Fourier series by means of displacement measurements. This method is based on the synthesis of invariant relations that make it possible to interrelate the variables of a special extended dynamic system and determine unknown variables as functions of known ones. The asymptotic convergence of estimates of unknowns to their true values is proven. The results of numerical simulation of the proposed method for the Duffing oscillator are presented.
This article presents a study on the behavior of rectangular functionally graded plates under thermo-mechanical bending conditions. The study employs a finite element method to analyze these plates, consisting of functionally graded face sheets and core. Validating the proposed model's accuracy through comparisons with existing literature, the investigation explores the effects of key parameters thermal load, geometric factors, and volume fraction distribution on thermo-mechanical bending behavior. The study includes a thorough parametric analysis to identify significant factors impacting normal stresses and deflection of functionally graded plates. The findings offer valuable insights for designing functionally graded plates subjected to combined thermal and mechanical loads. With its simplicity and potential for future advancements, the suggested method proves highly suitable for addressing these problems.
A field theory incorporating Edwards-Vilgis slip-link elasticity with Flory-Huggins mixing is developed for dual-layer gels containing rigid cores, capturing chain entanglement effects neglected by Neo-Hookean models. Physics-informed neural networks (PINNs) transform complexities of handling interfacial constraints into a neural network optimization problem, thereby reducing both algorithmic complexity and implementation requirements. Systematic parametric studies demonstrate that micromaterial parameters critically govern stress distributions, solvent concentration profiles, and swelling behavior. The framework enables precise control of target solvent concentrations and equilibrium configurations through optimal micromaterial parameter selection and thickness ratio design in dual-layer spherical gel systems.
The accurate calculation of stress intensity factors (SIFs) constitutes a critical yet challenging task within linear elastic fracture mechanics. While the universal weight function method (WFM) has emerged as a prominent approach due to its high computational efficiency, its predictive accuracy is often constrained. This limitation arises from the difficulty in characterizing the nonlinear mapping relationships between the geometric dimensions of cracked bodies and the requisite weight function parameters. To address these challenges, this study introduces an innovative machine learning-augmented universal WFM. This method leverages Gaussian process regression (GPR) models to characterize the nonlinear mapping relationships between the geometric dimensions of cracked bodies and the weight function parameters, thereby enhancing the computational accuracy of the universal WFM. Validation cases demonstrate that the proposed method achieves superior accuracy compared to the traditional universal WFM, with the maximum relative error not exceeding 5.09%.
For the thermal fatigue problem of the hypersonic aircraft's plate, a loose coupling analysis method is proposed to conduct vibration fatigue behaviour analysis of the cracked plate under a uniform temperature field. The temperature field is converted into additional loads, and the interaction mechanism between thermal coupling and crack propagation is explored. The modal, dynamic response and fatigue life analyses are conducted synchronously. The numerical simulation method is applied to verify this theoretical method. The results indicate that the analytical method proposed has sufficient computational accuracy, and the influence of the temperature field on vibration fatigue behaviour cannot be ignored.
An improperly designed pseudo-inclination angle in steeply inclined coal seams can lead to coal wall spalling and hydraulic support failure. This study establishes mechanical models for initial and periodic roof fractures under pseudo-inclined mining and derives analytical solutions using the variational method. The optimal pseudo-inclination angle has been determined to be 5 degrees to 10 degrees. Field monitoring shows that initial fractures occur at the center of the working face, while periodic fractures originate in the upper-middle section, where support loads are also highest. These results validate the mechanical model and offer theoretical guidance for the safe mining of steeply inclined seams.
This study aims to analyze the thermal conductivity, dynamic viscosity and rheology of corn oil (CO) with added graphene nanoplatelets (GNPs). The addition of GNPs to CO uses variations of c = 0.10%, c = 0.15%, c = 0.20%, c = 0.25%, and c = 0.30%. The highest thermal conductivity results were produced at a GNP percentage of c = 0.30% with a value of 0.1620 W & centerdot; m-1 & centerdot; K-1. The viscosity results show that the highest dynamic viscosity value is produced at GNPs c = 0.20% at all temperatures. The rheology results show that the stable percentage 0.10% and 0.20% approaches Newtonian properties.
The growing mass of modern vehicles increases kinetic energy and thermal stress on braking systems, elevating rotor temperatures and the risk of brake fade. In ventilated disc brakes, heat dissipation depends strongly on the geometry of internal vents. This study uses finite element method (FEM) simulations to examine the thermal behaviour of passenger-car ventilated rotors with different vent designs, including motorsport-inspired configurations, under high thermal loading. While previous studies have examined heat generation and dissipation in disc brakes, direct comparative FE analyses of vent geometries remain limited. The results demonstrate that vent shape significantly affects cooling performance during and following intense braking.
