Search

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]

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]

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]

• 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]

• 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]

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]