Archive of Applied Mechanics最新文献

Intelligent magneto-responsive structures are widely used due to their fast response speed and noncontact control. In this study, the peeling behavior of a slender magneto-responsive sheet under the magnetic field's action is investigated experimentally and theoretically. Firstly, two identical magneto-responsive sheets, with the liquid film adhesion and the absence of the liquid film respectively, are analyzed under the control of a cylindrical magnet. In addition, the peeling process is abstracted via the classical elastica model, and the expression of the potential energy functional is established. The approximate solutions of the deflection and the adhesion length of the magneto-responsive sheets during the peeling process are obtained based on the Rayleigh–Ritz method. The effects of the magnetic field generated by cylindrical magnets and the work of adhesion on the maximum deflection and adhesion length of magneto-responsive sheets are further predicted. The theoretically approximate solution agrees very well with the experimental data. These findings can provide new implications in a wide range of industrial areas, such as medical microsensors and intelligent structures for drug delivery.

The use of a simplified physical model of the tire of road vehicles is an efficient and simultaneous method to study the specifications of the entire chassis, including the tire specifications. Therefore, it is important to develop a simplified physical model that can be used in the early design phase when detailed computer-aided design data are not available. In this study, a vibration analysis of tires in road contact is described using frequency-based substructuring in a three-dimensional elastic ring model of a tire that includes a brush model simulating the tread rubber. By modeling the brush as a contact spring between the tire and the road surface, the natural frequencies and mode shapes of the tire under load conditions can be calculated using point-coupled three-way contact spring constraints. The experimental results show that the natural frequency changes significantly with road contact and does not depend on the vertical load. The theoretical analysis also showed that the natural frequency does not change when the stiffness of the contact spring is large enough to limit the displacement of the road contact, which is consistent with the experimental results. Unlike previous studies, this method calculates the mode shape with road contact based on the mode shape without road contact; therefore, the required model parameters can be determined based on the experimental modal analysis for the free-free condition.

This study presents a novel approach to real-time structural health monitoring employing convolutional neural networks (CNN) to calculate a loss factor that measures energy dissipation in structures. As mechanical properties degrade over time due to service loads, timely detection of defects is crucial for ensuring safety. The loss factor, derived from the vibration energy spectrum, is used to identify structural changes, distinguishing between normal operation, the presence of defects, and noise interference. Using large data from real-time vibration signals, this method enables continuous and accurate monitoring of structural integrity. The proposed CNN model outperforms traditional models such as multilayer perceptron and long short-term memory, demonstrating superior accuracy in detecting early-stage defects and predicting structural changes. Applied to the Saigon Bridge, the method offers valuable insight into long-term structural behavior and provides a reliable tool for proactive maintenance and safety management. This research contributes to a machine learning-based solution for improving structural health monitoring systems in critical infrastructure.

This paper numerically investigates the thermal behavior in a cylindrical tissue under non-Fourier boundary condition with dual-phase-lag bioheat transfer problem during thermal ablation. A hybrid method based on Legendre wavelets and finite difference approach are applied to determine an approximate analytic solution of the current problem. The correctness and feasibility of the present numerical scheme has been shown by comparing with exact solution under particular case. It has been observed that lower blood temperature gives rise to lower tissue temperature at the thermal ablation position. So, in order to get precise thermal data for treatment, blood temperature of particular patient must be taken into consideration for patient specific treatment. One of the main objective of this article is to minimize thermal damage outside the thermal ablation position. Our study demonstrates that outside the tumor position, normothermia condition exists, throughout the treatment time that reduces the risk of infection, minimizes thermal damages and ensure that patient feel comfortably well during the period. The specific heating plays a key role in the success of thermal ablation treatment and selection of Gaussian distribution source term helps to achieve the purpose. The radius of heat source, effective radius of heat flux and maximum heat flux generated are the important parameters of Gaussian heat source and computed thermal data strongly depends on them. The variation in the values of radius of heat source allows us specific heating(heating at a particular position) in the thermal ablation process so that the specific tumor can be treated. Both effective radius of heat flux and maximum heat flux applied gives the control of temperature at the thermal ablation position. Moreover, temperature rise at the tumor location is uniform in case of maximum heat flux applied. The present analysis will be helpful for medical community for better use of thermal data during thermal ablation.

This paper introduces a closed-form analytical approach to the postbuckling analysis of simply supported shear-deformable composite laminated plates under uniaxial compression. The analysis is based on three different laminate theories in order to explicitly account for transverse shear deformations and uses a geometrically nonlinear formulation in conjunction with the Ritz method in order to enable closed-form analytical expressions for the state variables of buckled composite plates. Results are presented for several different plate configurations, and a comparison is performed with literature results as well as comparative finite element computations which leads to a very satisfying results accuracy. The presented analysis method delivers results without any significant numerical effort and is thus especially suited for practical applications where such postbuckling analyses are performed many times.

Rotor stability analysis is essential to ensure rotating composite structures' safe and efficient operation. In this paper, the stability analysis of a hybrid composite shaft with two disks placed on elastic supports is investigated by the three-node finite element method. The strain potential energy of the hybrid composite shaft is calculated by considering the Timoshenko beam theory and using shape functions and the ABD matrix's effective components. The governing equations of the composite rotor are derived by replacing the kinetic energy of the shaft and disks, the strain potential energy, and the force of the bearings in the Lagrange equation. The equations of motion obtained from the finite element method are coded in the state space using MATLAB script. Their eigenvalues are calculated as a function of the rotor rotation speed, and the instability threshold of the composite rotor is evaluated. To validate the simulation results of the composite shaft in the free–free state in the ANSYS software, a hybrid composite shaft is made using the filament winding method, and its natural frequencies are extracted by performing the experimental modal analysis test. The instability threshold of the non-hybrid composite rotor of the presented model in different stacking sequences is compared with the results of the previous studies, and the validity of the three-node finite element method is confirmed. Finally, the effect of the fiber angle and the arrangement of the layers in the usage of carbon/epoxy and glass/epoxy in a specific stacking sequence on the stability of the hybrid composite rotor is studied.

In this work, a novel quadrilateral four-node element capable of simulating the axisymmetric-torsion deformation of small-scale solids of revolution is developed based on the consistent couple stress theory (CCST). To establish the element formulation, the C¹ requirement for displacement in the CCST is enforced in weak sense by using the penalty function method and the independent nodal rotation degrees of freedom are introduced into element construction to approximate the mechanical rotation fields. Besides, the stress functions that can satisfy the relevant equilibrium equation of the axisymmetric-torsion deformation are adopted as the basic functions for designing the element’s stress trial function. Several numerical tests are carried out and the results are compared to the solutions obtained using the analytical method or hexahedral solid element from the literature. It is shown that the new element exhibits good accuracy and captures the size dependences efficiently in prediction of the axisymmetric-torsion behavior of small-scale solids.

The present paper investigates the accuracy of the finite element method (FEM) in stochastic setting. The performance of the FEM for solving the transversal vibration eigenvalue problem of a uniform, homogeneous beam in presence of uncertainties is considered aiming to establish how accurate the method is in predicting the beam’s reliability as well as its probability of failure. An explicit solution is first provided for the approximate fundamental frequency of the beam as a function of the number of elements, for different boundary conditions when the mesh is uniform along the length of the beam allowing an analytical evaluation of the structural reliability and the probability of failure when, e.g., the random uncertainty in the Young modulus of the beam is considered. The exact solution of the vibration problem derived within Bernoulli-Euler beam theory is exploited to evaluate the actual reliability as well as the actual probability of failure which, being compared with required reliability or allowed probability of failure thresholds, permits to verify the accuracy of the FEM in the probabilistic context and to warn about “unreliability of reliability conclusions”.

The free vibration and traveling wave stability of a rotating ferromagnetic functionally graded cylindrical shell in magnetic and temperature fields are explored. The geometric and physical equations are determined within the framework of the Love’s theory. The expressions of kinetic energy and strain energy are obtained by considering temperature and rotation effects. The magnetoelastic theory is employed to establish a model of magnetic force. By using Hamilton’s principle and Galerkin truncation, the governing equations are obtained. The effects of different parameters on the natural frequencies of forward and backward waves are determined. It is found that the natural frequency undergoes separation of forward and backward waves due to the Coriolis force; with increase in the circumferential wave number, the frequency shows a trend of first decreasing and then increasing. The coupling effect of the magnetic induction intensity, rotational speed, power–law index, and thickness-to-diameter ratio leads to the nonlinear trend of frequencies. In addition, the influence of different parameter variations on the traveling wave stability is discussed.

Damage growth phenomenon in sheet metal forming processes is one of the most important issues in the manufacturing industries. Predicting the onset and location of crack can help engineers to postpone the failure as well as to produce safe parts. In this research, first, six different calibration methods are employed for the Bao-Wierzbicki damage criterion. Then, to evaluate the accuracy of the calibration approaches, a few conventional sheet metal forming processes with the positive stress triaxiality are numerically simulated. Finally, the numerical predicted results are compared with the empirical tests. The comparisons reveal that the hyperbolic quadratic hyperbolic 3 (HQH3) method is the best calibration approach, due to its accuracy and the fewer number of required experimental tests for the calibration.