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Thin-walled tubular deployable composite boom (DCB) has gained significant attention due to its lightweight, simple structure and high packaging efficiency. The experimental and numerical simulation methods were employed in this paper to investigate the folding behavior of the DCB. Using T700/epoxy unidirectional reinforced prepreg as raw material, DCB specimens were prepared by the vacuum bag method. To complete the folding experiments of DCB specimens, a folding mechanism was designed and manufactured. Folding experiments of DCB specimens were conducted and folding moment versus rotational displacement curves were measured. In addition, a Finite Element Model (FEM) was established to predict the folding behavior of the DCB. Different failure criteria were considered in the numerical analysis, including the Tsai‐Hill criterion and maximum stress criterion. Prediction results using the FEM were compared with experimental results, and both sets of results were in good agreement. It is shown that the DCB can achieve the folding function without failure. The research results in this paper are of great significance to the practical engineering application of the DCB. [Display omitted] • Six tubular deployable composite boom specimens and a precise folding mechanism were designed and prepared. • Folding experiments were conducted to measure the folding moment and rotational displacement curves. • A finite element model for predicting the folding behavior of the tubular deployable composite boom was established. [ABSTRACT FROM AUTHOR]

In order to analyze the impact angle of pick cutter, the angle of alloy head and the cutting line spacing on rock breaking effect, the three-dimensional model of rock cutting by pick cutter was established by solidworks, and the three-dimensional finite element model of rock breaking by pick cutter based on penetration failure and compression damage was established by using dynamic simulation software ANSYS/LS-DYNA. For the drum with a diameter of 1200 mm, a length of 900 mm and a rotational speed of 30 rot/min, when the impact angles of the picks are 30°, 37°, 45° and 52°, the angles of the alloy heads are 70°, 80°, 90° and 100°, and the intercept distances are 250 mm, 275 mm, 300 mm and 325 mm, the rock breaking simulation based on the finite element analysis software is carried out, and the load and specific energy consumption of the drum are obtained. Finally, through the analysis and comparison, the existing parameters are optimized, and a better parameter model is obtained. [ABSTRACT FROM AUTHOR]

Cracking failure of cement-treated base (CTB) has always been the concern of highway constructors. Mesoscale cracking analysis is an important means to study the damage degradation mechanism, which is difficult to be characterized by experimental techniques alone. The objective of this paper is to develop a random aggregate modelling method to simulate the mesoscopic cracking of CTB material. A minimum rectangle area method was proposed to calculate the polygon aggregate size, which is closer to the sieving analysis than the average radius method. A buffer zone method was proposed to determine the distance between randomly generated polygon aggregates. Based on the proposed random algorithm, finite element method (FEM) was adopted to build the mesoscopic model of CTB including aggregate, mortar, interfacial transition zone (ITZ) and air voids. Laboratory tests were conducted to validate the numerical model. Then the sensitivity analyses were conducted to study the influencing factors on cracking behavior. The simulation results indicate that the higher aggregate content and the finer gradation lead to the increase of ITZ, thus reducing the cracking resistance of the CTB material. Low porosity content is able to significantly reduce the stress concentration and thus improves the cracking resistance. The research results of this paper could be used to guide the crack resistant design of CTB material. [ABSTRACT FROM AUTHOR]

The purpose of the paper was to design geometric models of the movable connection made of brass for three different attachment options and three different loads. The numerical analysis of the mechanical properties, stresses, strains and displacements using the finite element method was carried out in SolidWorks 2020 and their comparative analysis was performed. The computer simulations performed will allow the boundary conditions that directly affect the mechanical properties of the engineering materials to be optimised [ABSTRACT FROM AUTHOR]

The paper presents a solution that can be used as a temporary supplement to the existing infrastructure in cases of natural disasters, during structure or bridge repair, in military applications and in areas where it is necessary to provide a floating system crossing. The genesis of the proposed structure and its development, as well as examples of applications of the basic module, referred to as the river module – the floating cassette with the pneumatic pontoon – are presented. The original solutions, such as the bow–stern modules, designed using modern, light and durable materials acting as deflectors, are also described. Examples of the use of floating structures composed of identical/repeatable modules–cassettes are shown. The results of experimental tests of two prototype river modules sets are presented as a validation for numerical studies. Selected aspects of static, kinematic and dynamic analyses using finite element and multibody simulations are presented. The numerical simulation of the prototype floating bridge with an assessment of the impact of clearances and an estimation of the kinematic parameters of the floating ribbon with various configurations are described. [ABSTRACT FROM AUTHOR]

Finite element analysis is one of the key steps in evaluating the effectiveness of an isolation system. The aim of this paper is to research the mechanical properties of sliding and rolling friction systems and their application for isolating frame structures. A hybrid seismic isolation system is proposed, which aims to protect the superstructure by reducing dynamic response. The effect of different parameters on the friction coefficient of the isolation bearing was tested using a compression-shear testing machine, and the results showed that various parameters significantly affected the friction coefficient. In addition, a numerical analysis finite element model was established using SAP2000 software to compare the seismic isolation performance of the hybrid isolation system with that of traditional seismic-resistant structures. The results showed that the composite isolation system not only effectively reduced inter-story shear and acceleration, but also slightly enhanced the seismic isolation effect as the friction coefficient decreased. [ABSTRACT FROM AUTHOR]

Recently, hydroforming has paid dividends in composite forming due to its uniform pressure distribution, which helps in reducing the delamination defects. Considering the need to develop an appropriate criterion for evaluating the formability of FMLs, inspired by sheet metal forming and testing, the uniform pressure loading test was adopted to characterize the formability of semi-cured FMLs by forming limit curve (FLC). In this paper, both theoretical analysis models considering and ignoring the tangential cohesive effect were established, and the stress expression of the critical zone was given. The results show that the tangential cohesive stress demonstrates a non-negligible influence on the FLC. A new form of comprehensive FLC was given by defining global equivalent strain and global strain ratio and analyzed by the finite element method. In addition, the numerical simulation model and the experimental parameters were verified. A simplified Hashin criterion was proposed and developed into the numerical simulation as a subroutine based on theoretical analysis. Parameters such as blank holder pressure, pressure rate, and temperature were considered both in experiments and simulation. Only fiber stretching damage was distinguished in the cross, single, and arc crack but no wrinkling. As predicted theoretically, a lower forming limit is expected when FMLs are subjected to greater tangential cohesive stress. Finally, with the help of numerical simulation, the influence of different boundary conditions on the comprehensive FLC was studied. Instead of a simple evaluation of FMLs, this comprehensive FLC could be used directly to optimize hydroforming processes in the engineering field. [ABSTRACT FROM AUTHOR]

In this paper, we study a frictional contact model which takes into account the damage and the memory. The deformable body consists of a viscoelastic material and the process is assumed to be quasistatic. The mechanical damage of the material which caused by the tension or the compression is included in the constitutive law and the damage function is modelled by a nonlinear parabolic inclusion. Then the variational formulation of the model is governed by a coupled system consisting of a history-dependent hemivariational inequality and a nonlinear parabolic variational inequality. We introduce and study a fully discrete scheme of the problem and derive error estimates for numerical solutions. Under appropriate solution regularity assumptions, an optimal order error estimate is derived for the linear finite element method. Several numerical experiments for the contact problem are given for providing numerical evidence of the theoretical results. [ABSTRACT FROM AUTHOR]

Walking-induced vibration control in wood floors is a critical issue attracting the attention of many researchers and engineers. This paper presents an experimental study applying static deflection tests, modal tests, and pedestrian load tests to a series of full-scale 12 m span tooth plates connected to wood truss joist floors with strongbacks and partition walls. A comparison of the calculation error of vibration parameters between the theoretical formula and a numerical model was also conducted. The results show that strongbacks and partition walls effectively reduce both the vertical displacement and the root means acceleration at the center of the floor under pedestrian load but increases the natural frequency. The partition wall can achieve a better vibration-reduction effect than strongbacks. The error of the finite element model is higher than that of the theoretical formula. Using the theoretical formula in engineering wood floor design is recommended. [ABSTRACT FROM AUTHOR]

The aim of this work is to develop a numerical tool for computing the weak periodic solution for a class of parabolic equations with nonlinear boundary conditions. We formulate our problem as a minimization problem by introducing a least-squares cost function. With the help of the Lagrangian method, we calculate the gradient of the cost function. We build an iterative algorithm to simulate numerically the weak periodic solution to the considered problem. To illustrate our approach, we present some numerical examples. [ABSTRACT FROM AUTHOR]

• Proper quantification of joint rotational stiffness (JRS) of a flight intersection joint (FIJ) influences the dynamic characteristics of a flight vehicle. • JRS of an FIJ is often determined experimentally due to the lack of a right predictive model. • An analytical model is proposed to evaluate the JRS of a radial-type FIJ when subjected to an external bending moment. • Numerical analyses and experiments are performed on six different FIJ configurations. • JRS and moment-rotation behavior predicted by the proposed model are correlated with both experimental and numerical analyses. • Further, the effect of joint clearances on the behavior of FIJ is investigated through the present model. Joint rotational stiffness (JRS) of a flight intersection joint (FIJ) and its accurate quantification play an essential role in studying the dynamic modal characteristics of a flight vehicle. This JRS of a FIJ is mostly determined through elaborate experiments due to the non-availability of a reliable predictive model. Therefore, in this paper, an analytical model is proposed to evaluate JRS of a radial type FIJ when subjected to external bending moment. In this model, at first, the tensile and compressive part of the FIJ section is identified by determining the neutral axis position. The respective part's contributing stiffness is then estimated by employing a spring-mass model. Later, the JRS expression is derived from the moment equilibrium condition and expressed as a function of the stiffness of the tensile and compressive part and neutral axis position. Subsequently, finite element analysis (FEA) is conducted with different numbers of screws, followed by detailed experimental investigations. The proposed analytical model is validated with the results from FEA and experiments for different screw configurations of FIJ. Further, the proposed model is extended to account for the effect of joint clearances on the JRS and the corresponding moment-rotation characteristics of the FIJ. [Display omitted] [ABSTRACT FROM AUTHOR]

We present an enhanced approach to solving the combined non-linear time-dependent Burgers-Fisher equation, which is widely used in mathematical biology and has a broad range of applications. Our proposed method employs a modified version of the finite element method, specifically the virtual element method, which is a robust numerical approach. We introduce a virtual process and an Euler-backward scheme for discretization in the spatial and time directions, respectively. Our numerical scheme achieves optimal error rates based on the degree of our virtual space, ensuring high accuracy. We evaluate the efficiency and flexibility of our approach by providing numerical results on both convex and non-convex polygonal meshes. Our findings indicate that the proposed method is a promising tool for solving non-linear time-dependent equations in mathematical biology. [ABSTRACT FROM AUTHOR]

• A numerical simulation method for the multifactor coupling of stress field and temperature field is developed. • The numerical simulation method is in good agreement with the experiment results at elevated temperatures. • The numerical simulative description of the grout material failure and fracture of a steel bar. • Prediction of the yield point and the ultimate point of FGSC from 25 °C to 1000 °C. Fire is one of the main objects of study at the cutting edge of the research on disaster prevention and mitigation in structures. In the event of a fire, the mechanical properties of the structural material will be significantly reduced, resulting in serious consequences. This paper simulates the tensile properties of sleeve grouting members at five different temperatures, to contribute to the research here. The simulated member stress-strain curves fit well with the corresponding experimental results. The paper introduces constitutive models of concrete, steel, and sleeve. Beyond that, a feasible finite element model of the grouted sleeve is proposed. Two special points' (yield point, ultimate point) coordinate formulas which are related to different temperatures (25–1000 °C) are presented. It indicates the regularity of fully-grouted sleeve tensile force-displacement curves in various temperatures. Meanwhile, the research content provides the basis for further research on reinforcing bars spliced by grout-filled coupling sleeves. [ABSTRACT FROM AUTHOR]

To study the force and deformation characteristics of a full-section immersed tube with post-pouring belt under the action of hydration reaction, the numerical model of full-section immersed tube with post-pouring belt was established by using MIDAS FEA (V2013) finite element analysis software, and the stress, cracking and deformation of the segment of the post-pouring belt were analyzed. The results show that under the action of hydration reaction, the concrete reaches the highest temperature at about 36 h, which appears at the roof of the tube gallery in the immersed tube, and the bottom steel plate expands rapidly initially, and subsequently shrinks gradually. The outer surface of the post-pouring segment concrete is stretched, and the internal region is under pressure, and as the internal temperature of the concrete cools down, the bottom plate starts to contract. The steel bar connection between the post-pouring belt and the surrounding immersed tube segment will increase the risk of cracking in the bottom plate of the full-section immersed tube. When only the steel bars in the bottom plate are connected, the maximum tensile stress of the immersed tube bottom plate will increase by 16.0% compared to the no connection case. If the steel bars of the immersed tube's web and roof are also connected, the maximum tensile stress will increase by over 20%. By connecting the steel bars, the peripheral tube section plays a certain role in limiting the transverse deformation of the post-pouring belt and constraining the reinforcement of the bottom plate and web (and roof) can reduce the transverse deformation of the immersed tube to a great extent, reducing the proportion by over 10%. [ABSTRACT FROM AUTHOR]

A thermo-hydro-mechanical-damage coupled model is developed in this paper for exploring the mechanism of thermo-hydro-mechanical-damage behaviors during enhanced oil recovery. The thermo-poroelastic deformation, two-phase flow and heat transport are all solved in finite element framework. Rock damage is determined by the tensile and shear failure criterions, and the contact problem for pre-existing fractures is based on the extended finite element method and augmented Lagrangian multipliers method. Then with the numerical framework, we simulated the damage evolution, fracture activation and rock properties damage caused by the thermo-poroelastic response during water injection in enhanced oil recovery. As the water injection and oil production are carried on, damage propagation and pre-existing fracture activation gradually appear around injection well. Complex fracture-damage network system and an enhanced permeability area are observed. The expansion of damage-enhanced permeability evolution to production well will greatly affect the oil recovery. And the fracture-damage network system and enhanced permeability area evolution is highly sensitive to the injection rate, injection viscosity and injection temperature difference. The simulations and discussions demonstrated that comprehensive modelling of thermo-hydro-mechanism-damage behaviors has important significance for enhanced oil recovery and other underground liquid injection engineerings. [ABSTRACT FROM AUTHOR]

The hydraulic fracture (HF) morphology and corresponding stimulated reservoir volume (SRV) are significantly dependent on the geomechanical factors of the formation. A better understanding of the hydraulic fracturing mechanism under different reservoir attributes is crucial for fracability evaluation and fracturing treatment optimization. In this work, the geomechanical controls on hydraulic fracturing in a heterogeneous formation and its fracability are investigated using a three-dimensional (3D) fully coupled hydraulic–mechanical–damage (HMD) model. Rock heterogeneity, which causes nonlinear progressive failure behavior, is considered in this model by assuming that the mechanical parameters of elements follow a Weibull distribution. The elastic damage mechanics and Darcy's law describe the damage process and fluid flow in elements, respectively. The element permeability is dependent on its state, which describes the effect of stress on the seepage field. The HF width is conceptually represented by the aperture of fractures, which depends on the failure mechanism of the damaged element. The coupled equations are solved numerically using the finite element method. The model is verified with experimental results of HF network propagation and multi-fracture interference. Then, a series of numerical simulations were performed to investigate the geomechanical controls of HF geometry and SRV in heterogeneous formations. At last, the optimal conditions for the formation of a complex HF network are further discussed according to the numerical results, based on which an improved fracability index is established. The results show that the numerical model can capture the 3D nature of the HFs and reproduce the HF network propagation and multi-fracture interference process. The complex HFs are more likely to generate in formations with high brittleness, large natural fracture (NF) density, small horizontal stress difference, and small fracture toughness. This study provides a reliable numerical method for hydraulic fracturing simulation and offers some reference for the fracability evaluation and fracturing treatment design in heterogeneous formations. [ABSTRACT FROM AUTHOR]