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The dynamic response description of materials in high-speed impact fields is of practical significance to structural design and practical engineering application. In this paper, an electromagnetic impact (EI) loading process was proposed to acquire dynamic stress-strain relationships of 2A10 aluminum alloys. A modified Johnson-Cook (J-C) material model was obtained by combining with Quasi-static experiments and verified by numerical simulations. Comparing the J-C model obtained by a Split Hopkinson pressure bar, the simulative results about maximum deformation displacements showed the modified J-C model was more in line with actual experimental results. The accuracy under the discharge energy of 4 and 5 kJ was improved by 50% and 11%, respectively. In addition, electromagnetic impact loading characteristics and microstructure evolution of materials were studied. The discharge current with an attenuated sine wave caused that electromagnetic impact forces demonstrated a bimodal trend. The maximum impact velocities reached up to 4.7 m/s and 6.7 m/s under the discharge energy of 4 and 5 kJ, respectively (the maximum strain rates are 655.0 and 932.3 s−1, respectively). The high-speed impact effect led to the emergence of adiabatic shear bands (ASBs) during deformation microstructure evolution. Due to higher impact speed, the deformation concentration degree was more remarkable under the energy of 5 kJ. [ABSTRACT FROM AUTHOR]

Fracture connectivity refers to the degree to which fractures within a rock mass are spatially arranged and interconnected. As a result, fracture connectivity can affect the pattern and magnitude of deformations, and induced brittle damage in response to external forces. Traditionally, fracture intensity has been a standard metric for characterising rock mass quality. This paper explains why fracture connectivity should be included in addition to fracture intensity as a characterisation parameter. Fracture intensity alone cannot capture the complex interactions and pathways that fractures create within the rock mass. On the other hand, fracture connectivity offers a more comprehensive view of how fractures propagate and interact, enabling a deeper understanding of stress transfer and deformation patterns. This paper reviews the Network Connectivity Index (NCI) and its applications in rock engineering design. It is discussed that NCI, considering both fracture intensity and fracture connectivity, serves as a more objective measurement to reduce the degree of subjectivity of many empirical methods. Furthermore, an extensive set of DFN models suggests that NCI correlates better with block sizes and can serve as a more representative parameter than P32\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${P}_{32}$$\end{document} for fragmentation assessment in cave mine design.Fracture connectivity can affect the pattern and magnitude of deformations and induce brittle damage in response to external forces.Fracture intensity has limitations in capturing the complex interactions and pathways that fractures create within the rock mass.Fracture connectivity offers additional information as to how fractures propagate and interact.The Network Connectivity Index (NCI) is a novel and objective measurement that can be easily extracted from discrete fracture network models.NCI correlates better with block sizes and can serve as a more representative parameter than P32 for fragmentation assessment in cave mine design.Fracture connectivity can affect the pattern and magnitude of deformations and induce brittle damage in response to external forces.Fracture intensity has limitations in capturing the complex interactions and pathways that fractures create within the rock mass.Fracture connectivity offers additional information as to how fractures propagate and interact.The Network Connectivity Index (NCI) is a novel and objective measurement that can be easily extracted from discrete fracture network models.NCI correlates better with block sizes and can serve as a more representative parameter than P32 for fragmentation assessment in cave mine design.Highlights: Fracture connectivity refers to the degree to which fractures within a rock mass are spatially arranged and interconnected. As a result, fracture connectivity can affect the pattern and magnitude of deformations, and induced brittle damage in response to external forces. Traditionally, fracture intensity has been a standard metric for characterising rock mass quality. This paper explains why fracture connectivity should be included in addition to fracture intensity as a characterisation parameter. Fracture intensity alone cannot capture the complex interactions and pathways that fractures create within the rock mass. On the other hand, fracture connectivity offers a more comprehensive view of how fractures propagate and interact, enabling a deeper understanding of stress transfer and deformation patterns. This paper reviews the Network Connectivity Index (NCI) and its applications in rock engineering design. It is discussed that NCI, considering both fracture intensity and fracture connectivity, serves as a more objective measurement to reduce the degree of subjectivity of many empirical methods. Furthermore, an extensive set of DFN models suggests that NCI correlates better with block sizes and can serve as a more representative parameter than P32\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${P}_{32}$$\end{document} for fragmentation assessment in cave mine design.Fracture connectivity can affect the pattern and magnitude of deformations and induce brittle damage in response to external forces.Fracture intensity has limitations in capturing the complex interactions and pathways that fractures create within the rock mass.Fracture connectivity offers additional information as to how fractures propagate and interact.The Network Connectivity Index (NCI) is a novel and objective measurement that can be easily extracted from discrete fracture network models.NCI correlates better with block sizes and can serve as a more representative parameter than P32 for fragmentation assessment in cave mine design.Fracture connectivity can affect the pattern and magnitude of deformations and induce brittle damage in response to external forces.Fracture intensity has limitations in capturing the complex interactions and pathways that fractures create within the rock mass.Fracture connectivity offers additional information as to how fractures propagate and interact.The Network Connectivity Index (NCI) is a novel and objective measurement that can be easily extracted from discrete fracture network models.NCI correlates better with block sizes and can serve as a more representative parameter than P32 for fragmentation assessment in cave mine design. [ABSTRACT FROM AUTHOR]

The present paper consists, firstly, of developing mathematical models to predict the stress concentration factor of a carbon fiber reinforced epoxy. Based on response surface method (RSM), a mathematical model has been determined, in which three factors with three levels are implemented. Carbon fiber content, fiber angle, and stress loading are chosen as the main input parameters in this study. The stress concentration factor is considered as an output response which is evaluated through finite element study. Secondly, the reliability of the stress concentration factor is proposed based on the developed mathematical models, where the dispersions of (i) the carbon fiber content and (ii) the fiber angle are taken into account using the Strength-Load method with the reliability index simulation. The proposed approach can be used as a powerful and an interesting method for engineering design to determine with more security the stress concentration factor behavior of a carbon fiber reinforced epoxy. [ABSTRACT FROM AUTHOR]

Behavior of beam-to-column connections in steel structures is characterized by the strength, stiffness and stability of them. Accurate modeling of stiffness, strength and ductility of these connections is important, especially when one considers dynamic or seismic loading. In this study, after determining the experimental behavior of the end-plate beam-to-column connection under cyclic loading, behavior of mechanical and neural network models of this connection has been evaluated. To validate the models, hysteresis response of mechanical model and computational intelligence model is compared with the experimental one. In the mechanical model, deformations of the connection are expressed only based on the geometric and material properties. On the other hand, in computational intelligence techniques with neural networks, requisite information is extracted directly from the experimental data. Hence, both models have pros and cons that are discussed in present paper. It is seen that as the mechanical model does not consider all aspects of hysteresis response, this model is not sufficiently accurate compared with neural network model. The neural network model is capable of characterizing pinching and stiffness degradation in hysteresis curve of the connection. [ABSTRACT FROM AUTHOR]

Prediction of flow stress of any engineering material is vital for modeling its plastic deformation process and for having estimate of force and power requirements in various manufacturing processes. The paper focuses on the application of two most important tools of artificial intelligence: computational intelligence and knowledge-based system, in predicting flow stress of a common high-strength low-alloy steel type, AISI 4340. The estimation process is based on different settings of material's microstructure (quantified by hardness), applied temperature, strain, and strain rate. The simulation results of both tools show a great deal of agreement with the experimental data. The prediction results are also compared with the estimations made by a commonly used empirical model. [ABSTRACT FROM AUTHOR]

Asymmetric continuum theory points to the equal roles of the rotation motions and those related directly to shear or confining strains. The strain motions could be quite independent or mutually related with the eventual phase shifts, while the displacements have only a mathematical sense; a real displacement may appear along the fracture slip only. Formally, any deformation could be presented as related to the displacements; however, its origin in a fracture source should be considered either as belonging to an individual process or to complex correlated events; in these cases, the confining, shear and rotation strains can be related mathematically to the different displacement fields. Some of these related deformations could be emitted from a source with a phase shift, while the observed displacements (deduced from records) result as a sum of these independent displacements. An important influence on a source process and on the premonitory micro-events has the material defects, their distribution, and mobility. The defect arrays lead to a concentration of stresses and their local reorganization. Thus, in this paper, we consider the induced stresses and strains related to defect content and to its modification and redistribution. Moreover, an important role in understanding the complex correlated events in a source plays the release-rebound mechanism. The release-rebound mechanism in an earthquake source processes leads to a possible direct or phase-shifted correlations between the emitted motions; in this aspect, a propagation of the coupled strain and rotation waves is discussed. In particular, we consider the point fracture events as related either to a confining load or/and to the shear and rotation processes; we discuss the related effects and their meaning when discussing the fault plane mechanism and emitted waves. In some important seismic regions, we have the recording system which permits to record the strains and rotations. However, we should point that the wordwide seismological network is not adequate to record the complex strain deformations released in the fracture processes and remains quite insufficient to understand the global stress changes and related strain waves of a very low period. Consideration on a recording mechanism of the long displacement waves indicates the insufficiencies of the present global recording system and points that recording of the global strain and rotation waves is an important and urgent task. [ABSTRACT FROM AUTHOR]

This paper considers the problem of equilibrium of a nonlinearly elastic spherical shell filled with a heavy fluid and resting on a smooth, absolutely rigid, flat surface. The weight of the shell is assumed to be negligible in comparison with the weight of the fluid filling it. The contact region with the supporting plane is one of the unknowns in the problem. Equilibrium equations for a membrane shell are obtained in an accurate nonlinear formulation. Stresses and strains of a shell made of a Mooney-Rivlin material are numerically investigated. The results are compared with calculation results for the case of inflation of a spherical shell ignoring the weight of the fluid filling. The effect of the fluid weight on shell strains and stresses is estimated. [ABSTRACT FROM AUTHOR]

The paper presents a computational and experimental investigation of integrated high-performance joints (IHPJs). The first type of the joints is presented by composite lugs and multiloop joints. Experimental and numerical stress analyses were carried out for single-loop specimens with different materials and geometrical parameters. Static and fatigue tension tests of IHPJs were also performed. The finite-element method and analytical methods were in good agreement in calculating the maximum tangential stress in the loop. Static failure criteria are proposed for the engineering design procedure. [ABSTRACT FROM AUTHOR]

Abstract  This paper investigates the design optimisation of a fuel flow vent hole (FFVH) located in the wing pivot fitting (WPF) of an F-111 aircraft assuming a damage tolerance design philosophy. The design of the vent hole shape is undertaken considering the basic durability based design objectives of stress, residual (fracture) strength, and fatigue life. Initially, a stress based optimised shape is determined. Damage tolerance based design optimisation is then undertaken to determine the shape of the cutout so as to maximise its residual strength and fatigue life. For stress optimisation, the problem is analysed using the gradient-less biological algorithm and the gradient-based nonlinear programming methods. The optimum designs predicted by the two fundamentally different optimisation algorithms agree well. The optimum shapes of the vent hole are subsequently determined considering residual strength and fatigue life as the distinct design objectives in the presence of numerous 3D cracks located along the vent hole boundary. A number of crack cases are considered to investigate how the crack size affects the optimal shapes. A semi-analytical method is employed for computation of the stress intensity factors (SIF), and an analytical crack closure model is subsequently used to evaluate the fatigue life. The 3D biological algorithm is used for designing the cutout profiles that optimise residual strength and fatigue life of the component. An improved residual strength/fatigue life (depending on the optimisation objective) is achieved for the optimal designs. The variability in SIF/fatigue life around the cutout boundary is reduced, thereby making the shape more evenly fracture/fatigue critical. The vent hole shapes optimised for stress, residual strength, and fatigue life are different from each other for a given nature and size of the flaws. This emphasises the need to consider residual strength and/or fatigue life as the explicit design objective. The durability based optimal vent hole shapes depend on the initial and final crack sizes. It is also shown that a damage tolerance optimisation additionally produces a reduced weight WPF component, which is highly desirable for aerospace industries. The design space near the ‘optimal’ region is found to be flat. This allows us to achieve a considerable enhancement in fatigue performance without precisely identifying the local/global optimum solution, and also enables us to select a reduced weight ‘near optimal’ design rather than the precise optimal shape. [ABSTRACT FROM AUTHOR]

Abstract  Based on the design sensitivity analysis for structural dynamics in time domain, an integrated control–structural design optimization method is proposed to the vibration control of piezoelectric intelligent truss structure. In this investigation, the objective function and constraint functions include not only the conventional design indexes of structure but also the vibration control indexes and the feedback control variables. The structural design variables are optimized simultaneously with the vibration control system. The sensitivity relations for the control–structure optimization model are derived by using a new method, and the sequential linear programming algorithm is used to solve this kind of optimization problem. The numerical examples given in the paper demonstrate the effectiveness of methods and the program. [ABSTRACT FROM AUTHOR]

This paper deals with the optimization of tools geometry in sheet metal forming in order to compensate for the springback effects after forming. A Response Surface Method (RSM) based on Diffuse Approximation is coupled with a new modified Inverse Approach for the rapid stamping simulation. The strains and stresses due to bending/unbending effects are calculated analytically from the final workpiece and used to evaluate the springback, using a second incremental approach based on the Updated Lagrangian Formulation. The ‘U-bending’ benchmark of NUMISHEET'93 has been used to validate the method; good results on the elimination of springback have been obtained. The final results are validated using STAMPACK® and ABAQUS® commercial codes. [ABSTRACT FROM AUTHOR]

The paper presents a topology optimisation method based on optimality criteria for total potential energy maximisation with a volume constraint. The final volume of the optimal structural configuration has not to be specified a priori and is directly controlled by the stress, displacement or stiffness constraints defined at the design problem layout phase. The proposed method leads to the identification of well defined structures characterised by a small number of discrete elements with intermediate material properties within a limited number of iterations. The results obtained by solving several two dimensional benchmark problems are shown. [ABSTRACT FROM AUTHOR]

Arrow’s theorem poses limits to the translation of the different preference orders on a set of options into a single preference order. In this paper, I argue, against opinions to the contrary, that Arrow’s theorem applies fully to multi-criteria decision problems as they occur in engineering design, making solution methods to such problems subject to the theorem’s negative result. Discussing the meaning and consequences for engineering design, I review the solution methods to such problems presented in the engineering design literature in the light of the theorem. It appears that underlying such methods is a mix-up of two fundamentally different problem definitions, as the theory of multi-attribute preferences, which is often presented as an adequate approach for engineering design, in fact fails to address the Arrowian multi-criteria problem. Finally, I suggest ways how engineering design might adopt results from discussions of Arrow’s theorem elsewhere in resolving its multi-criteria decision problems. [ABSTRACT FROM AUTHOR]

Engineering design research shows a rather fragmented, if not a chaotic, picture. But does it have a hidden order? Can we explore it, or should we impose a reasoning model? This paper looks for the answer in the purpose of engineering design. It is destined to sustain human existence and well being by virtual creation of artifacts and services for the society. To this end, the engineering design discipline should provide a proper body of knowledge. The design knowledge obtained by empirical exploration and/or rational comprehension should be transformed for practical/pragmatic deployment. It was assumed that this purposely streaming of design knowledge gives a unique rationale for engineering design research. Based on this, a framework of reasoning was constructed, including source, channel, and sink categories of knowledge and research of engineering design, respectively. Within each category, research domains, trajectories, and approaches were identified. The semantic relationships of domains, trajectories, and approaches form a hierarchical structure. The proposed framework enables a grounded argumentation about the order of engineering design research, as well as about the articulation of the engineering design knowledge. [ABSTRACT FROM AUTHOR]

The paper is devoted to design models in linearized solid mechanics. [ABSTRACT FROM AUTHOR]

In this paper, relative velocity at a given point on the wafer was first derived. The revolutions of wafer and pad are assumed the same and the axisymmetric uniformly distributed pressure form is given. Thus, a 2D axisymmetric quasic-static model for chemical-mechanical polishing process (CMP) was established. Based on the principle of minimum total potential energy and axisymmetric elastic stress-strain relations, a 2D axisymmetric quasic-static finite element model for CMP was thus established. In this model, the four-layer structures including wafer carrier, carrier film, wafer and pad are involved. The von Mises stress distributions on the wafer surface were analysed, the effects of axial, hoop, radial and shear stresses to von Mises stress and the effects of axial, hoop, radial and shear strains to deformation of the wafer were investigated. The findings indicate that near the wafer centre, von Mises stress distribution on the wafer surface was almost uniform, then increased gradually with a small amount. However, near the wafer edge, it would decrease in a large range. Finally, it would increase dramatically and peak significantly at the edge. Besides, the axial stress and strain are the dominant factors to the von Mises stress distributions on the wafer surface and the wafer deformation, respectively. [ABSTRACT FROM AUTHOR]