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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]

Regolith sampling is one of the core missions in deep space exploration. The design, optimization, and fabrication of samplers are challenging tasks to meet the requirements of deep space exploration, often necessitating complex modeling with computer-aided design tools and demanding the expertise of experienced space engineers with lengthy design iterations. We propose an interactive design framework where designers collaborate with optimization tool to streamline the design process. With the operator adjusting the design goals, we introduce Bayesian optimization to automatically suggest the next sets of parameters to explore. This approach is suitable for optimization scenarios when the design goals cannot be well established as analytical functions and fewer design iterations are required. In this paper, we design and optimize the core structure of the sampler under both stress analysis and discrete element analysis, considering lower stress, greater sampling volume per unit power consumption, and smaller size. Both simulation and physical experimental results show that the design proposed by our framework outperforms existing designs with a small number of design iterations. [Display omitted] • A computational design framework for searching forms of planetary regolith samplers. • The introduction of Bayesian optimization to reduce the cost in optimizing the shape in terms of efficient interaction with granular material. • Simulation and physical experiments to validate the proposed design from our framework. [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]

Metamodel technology provides an efficient method to approximate complex engineering design problems. However, the approximation for high-dimensional problems usually requires a large number of samples for most traditional metamodeling methods, which leads to the difficulty of "curse of dimensionality." To address the aforementioned issue, this paper presents the Net-high dimension model representation (HDMR) method based on the Cut-HDMR framework. Compared with traditional HDMR modeling, the Net-HDMR method incorporates two novel modeling approaches that improve the modeling efficiency of high-dimensional problems. The first approach enhances the modeling accuracy of HDMR by using the net function interpolation method to decompose the component functions into a series of one-dimensional net functions. The second approach adopts the CV-Voronoi sequence sampling method to effectively represent one-dimensional net functions with limited samples. Overall, the proposed method transforms complex high-dimensional problems into fitting finite one-dimensional splines, thereby increasing the modeling efficiency while ensuring approximate accuracy. Six numerical benchmark examples with different dimensions are examined to demonstrate the accuracy and efficiency of the proposed Net-HDMR. An engineering problem of thermal stress and deformation analysis for a jet engine turbine blade was introduced to verify the engineering feasibility of the proposed Net-HDMR. [ABSTRACT FROM AUTHOR]

The layout of the wing's internal structure not only dramatically influences the wing's strength stiffness but also directly affects the aerodynamic characteristics of the aircraft. Based on the original wing structure, a more flexible spatial design layout to achieve improved overall structural load-bearing performance, and a reasonable structural lightweight design are the research priorities to be considered for the development of future aircraft. Therefore, this paper attempted to design and analyze a lightweight airfoil that meets the performance requirements. Combining the strategy of hierarchical optimization design with the advantages of engineering bionics, the diatom Arachnoidiscus bionic structure, topological optimization, partial least squares regression (PLSR), and multi-objective particle swarm algorithm (PSO) are applied to optimize the placement and size of wing's internal components. The simulation results show that the weight of the optimized wing structure is reduced by 6% while satisfying the requirements of maximum stress and maximum deformation. [ABSTRACT FROM AUTHOR]

The conference was organised by European Technology Development (ETD Consulting), chaired by Dr Ahmed Shibli and co-chaired by Dr David Allen. Paper 1-4: B Experiences in the Manufacture of Large MARBN Steel Castings to the UK "IBN1" Specification b S. Roberts Goodwin Group, UK Goodwin Steel Castings have been a mainstay of the UK MARBN development programme over the past decade, and are now actively engaged in pursuing potential business opportunities worldwide. Paper 2-3: B The Development of Electromagnetic (EM) Sensor Technique for Creep Damage Detection and Assessment b J. Wilson I et al. i University of Manchester, UK; ETD, UK: Nippon Steel Technology Corporation, Japan The aim of this work was to establish correlations between "crept" and "aberrant" Grade 91 material and magnetic properties using laboratory measurement systems utilising Barkhausen Noise; which is connected with dislocation density. Paper 1-2: B Development of UK MARBN steel "IBN1" for advanced power plant applications b D. Allen ETD, UK This paper followed on from Prof. Abe's introduction by providing a more practical perspective and summarising the achievements of a decade of UK development of MARBN steel through a sequence of collaborative projects part-funded by Innovate UK. [Extracted from the article]

This paper investigates the mechanical behavior of ultra-high performance concrete-filled steel tubes (UHPCFST) subjected to repeated axial compression. A total of 34 specimens of UHPCFST were systematically designed, constructed, and evaluated experimentally. The design parameters encompassed steel tube wall thickness, UHPC type, specimen size (varying diameters while preserving a consistent diameter-to-thickness ratio), and loading scheme. The failure patterns, stress-strain relationships, axial load-bearing capacity, and stiffness were meticulously examined. Predominantly, shear failure and drum-shaped upsetting failure were identified as the primary failure mechanisms in the specimens. The axial load-bearing capacity was found to increase notably with the use of thicker steel tubes and higher-grade UHPC. Under repeated loading, a reduction in stiffness was noted, which was dependent on factors such as the steel content, tube diameter, and the volume of coarse aggregate of UHPC. Current predictive equations for the axial load-bearing capacity of CFST were assessed using the experimental results of UHPCFST and were determined to over-predict the axial load-bearing capacity of UHPCFST. Consequently, a refined equation is proposed to yield a more precise estimation of the axial load-bearing capacity for UHPCFST. Furthermore, an empirical model was developed to characterize the stress-strain behavior of UHPCFST under repeated axial compression, offering a tool for practical engineering design and analysis. • We tested UHPCFSTs under monotonic and repeated axial compression. • We proposed a compressive stiffness degradation formula. • We evaluated existing codes of practices. • We proposed an empirical load-strain model. [ABSTRACT FROM AUTHOR]

Wind-induced ovalling effect on the cylindrical wall of single flexible empty steel silo has been studied by various investigators in the past. The paper presents the same effect on cylindrical wall of ground elevated rigid (reinforced concrete) silo using a very simplified analytical approach, which may easily be accessed by practicing engineers for the purpose of design. An approximate analysis of circular cross-section of silo is performed to evaluate the effect of ovalling, but the same is much on conservative end, and also it cannot provide the effect to be taken into consideration for the entire height of the silo. To make the design procedure simple and costeffective, a few case studies have been performed using the actual wind load distribution and numerical/finite element model in Abaqus. The results obtained from the threedimensional finite element model of the silo show that the values of deformation and stresses obtained are much on lower end compared to the results of approximate analysis in bending of silo wall, whereas it also evaluates longitudinal stress which is equally significant. The paper also proposes graphs/charts to derive a modification factor over the values obtained by analytical/approximate method so that the designers and practicing professionals may take appropriate measures in the process of designing and detailing of the silo wall without going for detailed investigation of the model under consideration. [ABSTRACT FROM AUTHOR]

The jet grouting pile-mini steel pipe pile in soft soil area is composed of the jet grouting pile and the mini steel pipe pile. Through the analysis of the stress mode of the composite foundation under the overall compression of the pile top, the hypothetical diagram and calculation equation of the interfacial friction resistance distribution of the composite foundation are put forward. Thus, the calculation equation of the axial force of the mini steel pipe pile and the jet grouting pile is deduced, and the axial force distribution diagram of the mini steel pipe pile and the jet grouting pile in the composite foundation is defined. The vertical compression composite foundation in the field was selected for bearing capacity test and calculation and comparative analysis, and the relative error was 3%. Therefore, the stress mode and calculation method of the jet grouting pile-mini steel pipe pile proposed in this paper can meet the needs of engineering design and popularization and application of the composite foundation. [ABSTRACT FROM AUTHOR]

Spherical gear couplings efficiently transfer power between highly misaligned rotating shafts, featuring high longitudinal crowning in their design. At high misalignment angles, the contact point shifts across the face width, reducing the number of teeth in contact and increasing the risk of tooth root fatigue failure. While gear coupling fatigue sizing standards typically address misalignment angles above one degree as special cases, many applications involve misalignment angles exceeding 3°. This paper proposes a surrogate modeling approach to predict maximum tooth root stress for fatigue analysis of spherical gear couplings operating under misaligned conditions. Results indicate that this cannot be predicted in an independent manner from the number of teeth in contact or the effective face width. Consequently, demonstrates that using a single coefficient to account for the effect of the misalignment on load distribution yields optimal results. This research validates the suitability of the presented methodology for predicting tooth root stresses in spherical gear couplings prone to tooth root fatigue failure under high misalignment conditions with a mean error of 0.4%, while it serves as a valuable fast tool for engineers during the design phase. [Display omitted] • Analytically predicts misaligned gear couplings maximum tooth root stress accurately. • Methodology to build surrogate models from numerical results was proposed and proved. • Design variable interaction is crucial for stress prediction in misaligned conditions. • The effective face width dependence in the misalignment angle is lower than expected. • Unified factor accurately captures misalignment-induced tooth root stress changes. [ABSTRACT FROM AUTHOR]

The prefabricated urban utility tunnels (UUTs) have many advantages such as short construction period, low cost, high quality, and small land occupation. However, there is still a lack of in-depth analysis of the mechanical performance of the prefabricated urban utility tunnel (UUT) structure with bolted connections under different working conditions. In this paper, the force performance of a prefabricated UUT in Tongzhou District, Beijing, was studied under different working conditions using two methods: field monitoring and numerical simulation. The multichannel strain monitor was used for monitoring, and the internal wall concrete and bolt strain change data under the two conditions of installation and backfill were obtained. Combined with the construction process of the UUTs, a three-dimensional numerical model was established by COMSOL, where the build-in bolt assembly was used to simulate the longitudinal connection of the tunnel. The simulation results were compared with the measured data to verify the rationality of the computational model. The simulation results showed that the concrete and bolts on the inner wall of the tunnel work well under the two conditions of installation and backfilling; The deformation of the top plate of the prefabricated tunnel was approximately parabolic, with the largest vertical displacement (0.37 mm) in the middle and the most sensitive to the vertical load in the central part of the roof. The central portion of the side wall had the largest displacement (0.17 mm) in the inner concave. The tensile stress of bolt 3 increased the most (30.75 MPa) but was still much smaller than the yield strength of the bolt. The concrete and bolts of the UUT were found to work well through force analysis under operating conditions. In conclusion, analysis of structural forces and deformation failure modes will help design engineers understand the basic mechanisms and select the appropriate UUT structure. [ABSTRACT FROM AUTHOR]

The deformation performance and settlement failure mechanism of geosynthetics-reinforced soil (GRS) walls are the two key points of engineering design under the differential settlement. This paper presents model tests of deformation performance and failure mechanism of the GRS wall with and without lateral restriction under differential settlement conditions. The observation and measurement results, including force and vertical displacement of geosynthetics and lateral deformation of facing panels, indicate good settlement control performance of GRS wall during construction and under differential settlement. Results indicate that the influence of the stress state of facing panels on the settlement control performance of GRS wall cannot be ignored. And the differential settlement failure of GRS wall is likely to occur in the joint of facing panels and geosynthetics. For good illustrations, two analytical approaches about deformation and stress of geosynthetics were proposed based on elastic cable theory, in GRS wall with and without lateral restriction. The expressions exclude the necessity to carry out sophisticated numerical analyses to stress and deformation and may help to develop the design guidelines for such GRS wall. • Deformation and stress distribution are obtained by the mechanical analysis of elastic cable theory. • The critical stress value of geosynthetics is indicative of geosynthetic-reinforced soil wall destroy. • Failure of geosynthetic-reinforced soil wall is mainly caused by "stress concentration-fracture-separation" of geosynthetics. • The maximum stress is concentrated at the joint of facing panels and geosynthetics. [ABSTRACT FROM AUTHOR]

The objective of this research is to demonstrate that parts of decommissioned wind turbine blades can be repurposed for infrastructure applications for a sustainable future of the wind power industry. The purpose of this paper was to develop a methodology to conduct detailed structural engineering design of composite material parts extracted from wind turbine blades. A large section extracted from a 100-m long blade was repurposed as a roof for a small (approximately 40 m2) single-story masonry house. Geometric and material properties were taken from the blade design documents. A three-dimensional graphical model was created from the exterior surface and material layups. The roof was designed using the load and resistance factor design method familiar to civil engineers. Analysis of stresses and defections was conducted using hand calculations and the finite element method. The results of the analyses showed that the roof is within code mandated stress and deflection limits. The methodology developed could be applied to other wind blade repurposing concepts. [ABSTRACT FROM AUTHOR]

The paper proposes a fusion approach for damage detection in structural applications in the case of multiple damage locations and three-dimensional systems. Based on the Dempster–Shafer evidence theory, a multi-stage approach is proposed with the mode shapes assumed as primary sources and local decisions based on a flexibility method. The proposed approach has been applied to two case studies, a a fixed end beam analyzed in other papers and a three dimensional structures codified in a Benchmark problem. Both the case studies have shown the ability and the efficiency of the proposed approach to detect damage also in the case of multiple damage, limited number of identified parameters and noise measurements. [ABSTRACT FROM AUTHOR]

This paper focuses on the mechanisms and limits for the peak ice load values on inclined marine structures, and presents a buckling model, which explains well the phenomena behind the maximum peak ice loads. The study is based on two-dimensional combined finite-discrete element method simulations of the failure process of level ice against a structure. The simulations yield ice load records, which show consecutive peak ice load events. The complexity of the failure process makes the analysis on the mechanical phenomena behind the peak ice load events extremely challenging. The introduced buckling model assumes that the ice sheet breaks into separate ice floes in front of the structure before the maximum peak ice loads occur. The model is demonstrated to be able to quantify the effect of force chains, which have an important role in the ice-structure interaction process. [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]

Saturated impulse refers to the critical value after which the deflection of the beam or plate under pulse loading will not increase with further applied load. This paper investigates this phenomenon for rectangular plates under rectangular pulse-loading with various symmetric boundary conditions, e.g. two opposite edges of the plate are fully clamped while the other two edges are simply supported or free. For rectangular plates with symmetric boundaries under rectangular pressure pulse, the saturated duration and saturated impulse are merely dictated by the deformation mechanism, not by the boundary conditions. Then the effects of the aspect ratio and the boundary condition on the saturation impulse for elastic-plastic plates are revealed through numerical simulation. Bilinear elastic-plastic rectangular plates, with fully clamped boundaries and simply supported boundaries, subjected to rectangular pulse-loading are taken as typical examples. Subsequently, the saturation phenomenon is summarized from square plates to rectangular plates. The correlation is made between the results obtained from elastic-plastic analysis and those predicted by the rigid-plastic approximation. Finally, based on numerical simulation, theoretically and practically meaningful empirical expressions on the saturation phenomenon are proposed to facilitate engineering designs. [ABSTRACT FROM AUTHOR]

The present paper is concerned with deriving simplified design equations and charts for modelling in-plane expansion of fractured thermally pre-stressed soda-lime-silica glass panes using the method of equivalent temperature differences (ETD) together with a thermal expansion analogy for strains. The starting point is a theoretical method based on linear elastic fracture mechanics merged with approaches from stochastic geometry to predict the 2D-macro-scale fragmentation of glass. The approach is based on two influencing parameters of glass: (i) fragment particle size, δ , and (ii) fracture particle intensity, λ , which are related to the pre-stress induced strain energy density, U D , before fracture. Further Finite Element (FE) analysis of single cylindrical glass particles allow for establishing functional relations of the glass fragment particle dimensions, the pre-stress level and the resulting maximum in-plane deformation. Combining the two parts of two-parameter fracture pattern modelling and FE results on fragment expansion, formulas and engineering design charts for quantifying the in-plane expansion of thermally pre-stressed glass panes due to fracturing via an ETD approach is derived and provided within this paper. Two examples from engineering practice serve as demonstrators on how to use our ETD approach to compute the equivalent temperature difference and resulting internal forces as well as deformations. This approach serves furthermore as a basis to estimate secondary effects (such as fracture-expansion-induced deformations or stresses) on support structures or remaining parts of glass laminates in form of handy ETD load cases within analytical as well as FE analysis. • Parametric study of the expansion of a single fragment using the FE-method. • Tool for estimating the expansion of tempered glass when fractured. • Simple model for load transfer of laminated glass upon fracture of a single pane. • Two statistical regions in the relation between fragment size and strain energy. [ABSTRACT FROM AUTHOR]

In recent years, a method has been developed to measure current creep strength at nearly constant structure in a high precision stress relaxation test (SRT), covering at least five decades in creep rate in a one day test. Results have been reported on a wide range of metallic alloys, polymers, composites and ceramics. In the present paper it is shown that these same data can be used to determine a measure of intrinsic ductility over the same range of stress, using results on a low alloy Cr–Mo–V steel. This is based on an experimental and theoretical correlation between elongation at failure and strain rate sensitivity,m. This refined SRT test can now be used to evaluate both the intrinsic creep strength and the intrinsic ductility as a function of stress in a single short-time test. The test can detect embrittling phenomena at very low creep rates as a function of temperature. This measure of ductility may be used directly in engineering design and remaining life assessment. [ABSTRACT FROM PUBLISHER]

Abstract: Aseptic loosening is one of the main reasons for the revision of a total knee replacement (TKR). The design of the key component of a TKR, the femoral component, is particularly problematic because its failure can be the result of different causes. This makes the development of new biomaterials for use in the femoral component a challenging task. This paper focuses on the engineering design aspects in order to understand the limitations of current materials and design deficiencies. The paper describes the introduction of a new biomaterial for a femoral component and justifies the recommendation to use multi-functional materials as a possible solution to aseptic loosening. The potential advantages of applying functionally graded biomaterials (FGBMs) in prosthetic femur are explained by reducing the leading causes of failure including wear, micro-motion and stress-shielding effect. The ideas presented in this paper can be used as the basis for further research on the feasibility and advantages of applying FGBM in other superior implant designs. [Copyright &y& Elsevier]

X-section cast-in-place (referred to as XCC) pile, which is one of new pile types developed by Hohai University, is widely used for pile foundation and pile-supported embankment over soft ground in China. However, little research has been carried out on this new type pile, especially the surrounding soil disturbance under XCC pile installation. This paper presents an analytical solution for estimating the horizontal stress and displacement of surrounding soil of XCC pile after XCC pile installation. The reliability and accuracy of the present solution are verified by comparing them with the field test results. Then, parametric studies, such as outsourcing diameter (a), open arc distance (b), open arc angle (θ), the undrained strength (Su), the limit pile cavity pressure (Plim), and the radius of the plastic zone (Rp), are discussed for the practice engineering design. The results show that the stress and displacement distributions of surrounding soil calculated by this paper are in agreement with field test results. [ABSTRACT FROM AUTHOR]

Management of flexible pavements requires timely application of preventive maintenance and rehabilitation actions such as overlays. These actions are an integral part of a design strategy that minimises the use of recourses over the pavement's life-cycle. The objective of this paper is to develop a reliability model for flexible pavements that accounts for the effects of overlay designs. In this paper, the pavement responses are determined by the linear theory of elasticity for the system of pavement layers, while the pavement reliability is represented as a series system of two failure criteria: fatigue cracking and rutting. To illustrate the developed model, a numerical study is presented. Sensitivity and importance measures are computed for the parameters and the random variables included in the limit state functions. The sensitivity measures suggest that the initial asphalt layer thickness and the sub-grade stiffness are the critical predictors of the pavement performance after application of a structural overlay. [ABSTRACT FROM PUBLISHER]

When a pipeline crosses a landslide, it is subjected to combined loads, which can result in bending and subsequent ovalization of the pipe cross section. When compressive stresses cause buckling and ovalization, then the tensile stresses rarely result in these types of failures. Reliable mitigation measures could be carried out quickly at modest cost by performing a pipe stress-strain state assessment that takes into consideration elastic-plastic deformations. Therefore, this paper studied the response of the thin-walled cylindrical pipe subjected to combined beam load factors and internal pressure using a new engineering approach. This approach relied on a technique that reduces the problem to one dimension, and uses the plasticity and membrane theory of shells. A stress-strain diagram of pipeline material was obtained from the tensile test and was approximated with two linear dependences in the elastic and plastic zones. The actions of internal pressure, bending moment, and longitudinal force on the straight pipe element and distribution of stresses and strains in the pipe cross section were analyzed. The results of this paper show how variations of external loads affect pipe flexural rigidity and were compared with experimental outcomes. [ABSTRACT FROM AUTHOR]

This paper describes and demonstrates modifications of the harmony search method to support multimodal structural optimization. Several researchers have recognized the potential of population-based optimization methods, such as genetic algorithms and particle swarm optimization, to support multimodal optimization, that is, generating a range of good alternative solutions, rather than a single best solution. Among these population-based methods is the harmony search method, which has been demonstrated to be efficient and effective in many unimodal structural optimization problems. Toward the goal of making the harmony search method more effective in multimodal optimization, this paper describes a new strategy for generating solutions called close-harmony improvisation, and a new strategy for replacing solutions called local replacement. Examples demonstrate the effect of the two strategies used individually and in tandem. The discussion compares results with conventional harmony search and finds that close-harmony improvisation consistently improves the fitness of the search results, although the effect is sometimes mild, whereas local replacement is quite effective in increasing the diversity of the search result. [ABSTRACT FROM AUTHOR]

Abstract: From the practical point of view, the classical elastic shakedown methods are not very useful for design, since in most components the stresses can safely exceed the elastic limit locally. This paper generalizes the static shakedown theorem (Melan’s theorem) to allow the analysis of plastic shakedown. Since the method is derived from a lower bound formulation in shakedown, it is very useful for the design purposes (safe). The ratchet boundary is analytically determined using the proposed method for several examples with uniform stress distributions. The numerical implementation of the method along with several examples is discussed in an accompanying paper. [Copyright &y& Elsevier]

Abstract: The paper proposes a new approach for shape optimisation with fatigue life as the design objective. Conventional designs often incorporate stress optimisation that aims at reducing stress concentrations around a structural boundary by minimising the peak stress. However, this is only an effective and sufficient measure for an ‘ideal’ or ‘flaw-less’ structure. It is a well-known fact that flaws (cracks) are inevitably present in most structures. This emphasises the need to investigate the influence of cracks on optimised shapes. Numerical modelling of cracks using the Finite Element Method requires a fine mesh to model the singularity at crack tips, which makes fracture calculations computationally expensive. Furthermore, for a damage tolerance based optimisation, numerous cracks are to be considered at various arbitrary locations in a structure, and fatigue life evaluation needs to be repeated for each crack at every iteration. This makes the optimisation process extremely computationally inefficient for practical purpose. Moreover, the lack of information concerning crack size, orientation, and location makes the formulation of the optimisation problem difficult. As a result, there has been inadequate research to consider fracture parameters, such as fatigue life, in the optimisation objective. To address this, the paper presents an approach for the shape optimisation of damage tolerant structures with fatigue life as the design constraint. The damage tolerance based optimisation was performed using a number of nonlinear programming algorithms, namely the Broydon–Fletcher–Goldfarb–Shanno (BFGS) method, the Fletcher Reeves (Conjugate Direction) method, and the Sequential Unconstrained Minimisation Technique (SUMT). These methods were extended for optimising the fatigue life in the presence of numerous surface cracks. A significant enhancement in fatigue life was achieved for various crack cases consisting of different initial and final crack sizes. It is shown that the fatigue life optimised shapes can be considerably different from the corresponding stress optimised solution. This emphasises the need to explicitly consider fatigue life as a distinct design objective when optimising damage tolerant structures. A fatigue life optimisation leads to the generation of a ‘near uniform’ fatigue critical surface. The design space near the ‘optimal’ region was found to be relatively flat. This means that the precise identification of the local/global optimum solution is not critical, because a significant structural performance enhancement can be achieved in the ‘near’ optimal region. An additional benefit of fatigue life optimisation is that the resulting optimised shapes may even be lighter than the stress optimised designs. To verify the optimal solutions obtained using the nonlinear programming algorithms, the results were compared with those obtained using a heuristic optimisation method (Biological algorithm). The solutions predicted by both the methods, employing inherently different (gradient-based and gradient-less) algorithms, were found to agree very well. [Copyright &y& Elsevier]

Much modern engineering design work uses S–N curves and empirical applications thereof. In industry, currently popular methods for predicting fatigue life under complex loading use ad hoc cycle counting algorithms along with Miner's rule, in spite of its known weaknesses. Many ad hoc alternatives to Miner's rule have been proposed, each with limited experimental justification. Of these, Manson's double linear damage rule (DLDR) is widely considered to be good. In this paper, we bring a new perspective to empirical, as opposed to mechanistic, fatigue damage evolution models. It is first assumed, with reasonable justification, that there is a scalar, abstract, damage variable ϕ, whose evolution under cyclic loading satisfies ϕ=aϕm, where a and m are unknown functions of load parameters. One main contribution of the paper lies in deducing what the functions a and m must be in order to obtain consistency with fatigue data in handbooks. A small correction to this basic power law model is then developed. The final explicit model initially has 10 unknown fitted parameters, but these are brought down to three unknowns; the accompanying discussion is the other main contribution of the paper. Finally, comparison with Manson's and other data suggests that, with two fitted parameters, our model works as well as the DLDR and much better than Miner's rule. For other parameter choices, our model reduces to Miner's rule. We conclude with speculation about ways in which the model might be extended beyond the scope of the DLDR. [ABSTRACT FROM AUTHOR]

This paper presents a patient transfer apparatus between bed and stretcher. This apparatus makes it possible for the nurse to move weak, injured, or paralyzed patient from bed to stretcher, or vice versa, alone. Moreover, the suffering, stress, and uneasy feeling of the patient can be alleviated. This paper describes the specification, mechanical design, control system, and motion control of the apparatus. A special devised mechanism is developed, and a new servo system is used in this control system. The control principle and algorithm of the new servo system are proposed, and the motion-control method and safety function of the apparatus are described. The experimental results and evaluation indicated the effectiveness of this system. [ABSTRACT FROM AUTHOR]

Abstract: The present paper aims to study the cylindrical section of a Type 3 high-pressure hydrogen storage vessel, combining an aluminium liner which prevents gas diffusion and an overwrapped composite devoted to reinforce the structure. Today, this technique is widely used but still requires consistent time investments whenever a competitive solution, involving to definitely increase weight efficiency, is needed. The laminate composite is assumed to be an elasto-damage material whereas the liner behaves as an elasto-plastic material. Based on the classical laminate theory and on Hill''s criterion to take into account the anisotropic plastic flow of the liner, the model provides an exact solution for stresses and strains on the cylindrical section of the vessel under thermomechanical static loading. Part I focuses on the theoretical background. The effect of the stacking sequence on the gap occurrence, on the residual stress magnitude and on the structure stiffness may then be investigated. This will be done and be compared with results of experiments which are carried out on prototypes in the second part of this paper before an optimization is performed. [Copyright &y& Elsevier]

Abstract: Sheet metal formability is conventionally assessed in a two-dimensional plot of principal strains or stresses in comparison to a forming limit curve. This method of assessment implicitly assumes that the forming limit is isotropic in the plane of the sheet. While the assumption of isotropy in the forming limit is perhaps a good engineering approximation, it is intrinsically inconsistent with the use of material models that are anisotropic. Since the trend today is to utilize models with full anisotropy in order to more accurately capture the physics of material behavior, the issue of anisotropy of forming limits must also be addressed. The challenge is that the forming limit is no longer defined by a curve but requires the definition of a surface in strain or stress space, and therefore it is no longer appropriate to view these limits with the convenience of two-dimensional diagrams. Furthermore, recent developments in the characterization of sheet forming limits under non-proportional loading suggest that is advantageous to view forming limit behavior in terms of stresses rather than strains, a view that is adopted in this paper. A solution to the challenge of assessing formability for an anisotropic material is proposed that rescales the stresses by a factor so that the scaled stresses have the same relationship to a single forming limit curve in a 2D plot in stress-space, as the actual stresses have to the true anisotropic forming limit in 3D space. The rescaling enables engineers to accurately view the formability of all the elements at the same time for a given finite element analysis of an application. This paper also discusses other challenges of using stresses in the assessment of formability, focusing on an analysis of the 2-Stage Forming Benchmark highlighted in the Numisheet ’99 Conference. Stresses are found in this application to unload to non-critical values after reaching critical levels earlier in a forming process, which suggests that a full integration of the stress-based forming limit criterion with FE simulation is required to detect critical states that may temporarily occur during the forming process. [Copyright &y& Elsevier]

Tension structures, in the form of preestressed cable nets and fabric roofs, are becoming a permanent feature of modern architecture. Their popularity can be attributed to their aesthetic appeal, improved durability and the development of computational analysis techniques that facilitate the design process. Despite progress and growing interest in tension structures, their behaviour and complexities of design are not fully understood, except by a few specialists working in the field. This paper introduces the topic, outlines practical difficulties and discusses misconceptions related to the design of tension structures. The main focus of the paper is placed on a process known as form-finding-an issue that affects practically every aspect of design and construction. A way forward, suggested in the closing part of the paper, aims to provoke discussion on the role of engineering education and the division of labour between architect and engineer. [ABSTRACT FROM AUTHOR]

In general, a strain gauge embedded in a model is subjected to a stress normal to the grid, whereas a gauge on the external surface is free from such a stress. This paper concerns the effect of the stress normal to the grid on the output of the strain gauge; usually, the influence of such a stress has a negligible effect, however, in some cases a notable influence has been noted. Therefore, the output of the strain gauge is determined in function of the strains in the plane of the gauge, ℇl and ℇt, and of the stress, σn, normal to the grid. The analysis shows that the output of the strain gauge is influenced by the coupled effect of transverse sensitivity and pressure sensitivity of the strain gauge. In particular, the analysis shows that, for Constantan gauges compensated for steel, the influence of the transverse sensitivity is in general prevailing on that one due to the pressure sensitivity. The results reported in this paper explain the experimental data obtained by various researchers. [ABSTRACT FROM AUTHOR]

Abstract: In the free axisymmetric blowing of hollow axisymmetric forms, a stable anuerism often develops which then travels through the form. This paper presents a procedure for carrying out experiments where by stresses and strains can be measured during axisymmetric free blowing. This paper explores the relation ship between material properties and this behaviour to explain the conditions under which stable anuerisms can occur. [Copyright &y& Elsevier]

This paper presents a general design procedure for calculating the moment capacity of sections containing unstiffened elements with stress gradient. The method uses design equations for effective widths of unstiffened elements with stress gradients based on plate test results. Current international design provisions allow the capacity of sections that contain stiffened elements with stress gradients to be calculated on the basis of inelastic reserve capacity, whereas sections that contain unstiffened elements must be designed on the basis of initiation of yielding in the section. This paper presents methods for the calculation of the capacity where inelastic reserve capacity may be taken into account, for sections containing fully effective unstiffened elements with stress gradient. The methods are shown to be in good agreement with experimental data of I-sections and plain channels in minor axis bending. Particular attention is given to the effect of both the elastic buckling coefficient used in the effective width method, and the use of inelastic considerations, on the bending capacity. Specific design proposals are presented in the form of amendments to the current American and Australian standards for cold-formed steel structures, for elements (effective width equations) and sections in bending (inelastic reserve capacity equations). [ABSTRACT FROM AUTHOR]

This paper investigates the effects of both external moment and different heating schemes on thermally restrained steel columns. Only the cross-sectional uniform heating profile is studied. A self-developed finite element program FEMFAN is applied in this study. The first part of the paper investigates the developments of column internal forces as well as cross-sectional stresses and strains for a heated column subjected to both external axial load and two moments acting on opposite ends. It shows that such external moments can significantly reduce the critical temperature of pin-roller columns, while they have very limited effect on rotationally restrained steel columns due to the moment restoring effect. Thus, for typical rotationally restrained steel columns, the external moment need not be included in the calculation of the load utilisation factor, when calculating the column critical temperature. The second part of the paper studies the effects of both rapid and slow heating schemes on column critical temperature. Creep is found to dominate the column behaviour beyond 450 °C, and under a slower heating rate. [Copyright &y& Elsevier]

The lack of appropriate structural design standards for composite materials is a major inhibitor to the wider usage of these materials in mainstream civil engineering. In 2000, the Composites Institute of Australia (CIA) moved to address this problem on a national level and initiated a programme to develop an Australian industry code of practice for the structural design of fibre composites. This paper discusses two of the initial topics addressed by this programme: the development of a national system of grading and certification for composite constituents, and an alternative approach to the characterisation of unidirectional lamina behaviour. The paper outlines the basis for investigation of each of these topics, and discusses the research approach that has been adopted. In the case of characterisation of lamina behaviour, the paper also presents initial results from associated experimental programmes. [ABSTRACT FROM AUTHOR]

Polymers are widely used in applications where they may be subjected to impact loading leading to high strain rate deformation. Plastic work on deformation generates heat in the material. At high strain rates, there is insufficient time for this heat to diffuse out of the material, leading to adiabatic conditions. This leads to post-yield thermal softening in the mechanical response, which modifies the material response and must be considered in Engineering design. In this paper, a novel technique is presented in which this adiabatic self-heating can be simulated experimentally at low strain rates using programmed temperature profiles. We show that, in some cases, these simulations can very accurately capture the mechanical response at higher rates, but in others, the replication is less accurate. This may give further insights into the thermodynamics of high strain rate polymer mechanics. This technique therefore enables a number of avenues of research: the work to heat conversion can be investigated systematically; diagnostic tools that are limited to low strain rates can be applied; and we can better understand material behaviour and thereby improve predictive models. • Polymers deformed under high strain rate loading see large strain thermal softening. • Thermal softening from adiabatic heating is complex and modifies material response. • A novel approach has been presented to study this behaviour at low strain rates. • Low-rate simulations can closely capture polycarbonate behaviour seen up to c. 10/s. • Approach provides insights into potential high-rate structural evolution mechanisms. [ABSTRACT FROM AUTHOR]

This paper aims at proposing a new fatigue life estimation model that is preferably adapted to welded joints subjected to multiaxial loading. First, a mesh-size insensitive structural stress is defined that enables to characterize the stress concentration effect appropriately. Second, the multiaxial stress state and loading path influence are taken into account in the lifetime prediction model by adopting a suitable critical plane method, originally proposed by Carpinteri and co-authors. Experimental verification is conducted for a given welded joint geometry under different loading conditions, including uniaxial, torsional and multiaxial loads. The reliability and effectiveness of the new method are validated through substantive fatigue testing data. [ABSTRACT FROM AUTHOR]

This paper presents a study of scanning electron microscope surface morphology and the reflectivity of the mode II fractured surface of graphite/epoxy laminates. A discrete number average method was developed for the quantitative characterization of hackles formation. The variation of hackle marks linear density with impact energy for end-notch flexure and centre-notch flexure for pure mode II loading were determined. The results indicated that hackles formation decreased with impact energy and the maximum hackles formation were observed at the centre area. Reflectivity was observed to be increased with the angle of reflection and decreased with impact energy, which is in agreement with the scanning electron microscope analysis. With the incident light scanned in the transverse direction, the intensity of the reflected light increases much more exponentially compared with along the fibre direction. Reflectivity in the fibre direction was clearly lower than in the transverse direction in the damaged area. The greater the damaged area, the less the intensity (reflectivity) of light reflected. [ABSTRACT FROM AUTHOR]

This paper discusses two distinct benefits associated with product reliability qualifications by combining individual reliability stress tests into a single test. First, a combined test will make better use of test equipment, personnel and product samples required for the qualification, implying a cost benefit. Secondly, a combined test allows interaction between the stress sources to occur on all failure causes. These benefits were realized as a result of a power supply application. Each individual test was designed to address specific causes which are assumed to be totally independent of other failures. A combined test can verify or deny independence and therefore provide a stronger practical test. Hence, this paper will demonstrate that a combined reliability test will provide more efficient testing with solid engineering product performance coverage. In addition, an approach is proposed for combining tests which fixes the acceleration rates between stress tests as the same ratio as under the nominal operating product environmental conditions. [ABSTRACT FROM AUTHOR]

The scaled boundary finite element method is employed to obtain highly accurate solutions of the stress intensity factors (SIFs) and T-stress for standard homogeneous and bimaterial fracture specimens. The solutions are assembled into a practical database (up to 6 significant figures) corresponding to various crack lengths. Using a curve fitting technique, precise Padé approximants of the SIFs and T-stress are also developed, which retain a maximum error of <0.28% for any specimen. The findings of this paper are useful for engineering analysis and design, as well as verification of current and future numerical schemes for computing SIFs and T-stress. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper presents an innovative flexibility analysis as a practical, effective procedure to improve the expected value of large-scale, capital-intensive projects when there is market uncertainty. Its novelty lies in its approach and scope. Its approach develops understanding of the drivers of the value of flexibility, so as to build acceptance among decision-makers. Its scope explicitly considers the combined effects of uncertainty, economies of scale, learning, and geographic distribution. It demonstrates how these factors combine to impact the benefits of flexibility in the early stages of design and project evaluation in the context of uncertainty. It makes this point through a specific example: the long-term deployment of liquefied natural gas (LNG) technology to supply the transportation market. It contrasts the base case fixed design (a big centralized production facility) with flexible modular designs that phase capacity additions over time and space. The proposed flexibility method compares design alternatives based on several indicators of economic lifecycle performance (Net Present Value (NPV), Initial Capex, etc.). Results indicate that flexible modular deployment strategies can significantly improve the economic performance of large, expensive projects. As sensitivity analyses show, the improvements can be significant over a wide range of analytical assumptions. An important insight is that higher learning rates increase the benefits of flexibility, counteracting the effects of economies of scale. Overall, the study shows that flexibility in engineering design of major production facilities such as LNG plants has multiple, supporting advantages due to uncertainty, learning, and location. [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]

This paper investigates the thermo-mechanical constitutive relationships of a CoCrFeNi high-entropy alloy (HEA) from quasi-static 10−2/s, medium strain rate of 101/s to high strain rates of 5 × 102/s-1.1 × 104/s. A series of tests, with the use of cylindrical specimen and shear compression specimen (SCS), were performed on a hydraulic Instron machine and a split Hopkinson pressure bar (SHPB) synchronized with a high-speed camera. The temperature rise (self-heating) during medium strain rate deformation is evaluated experimentally. Effects of the environmental temperatures on the dynamic flow response are studied using the SHPB and an environmental chamber. The constitutive relationships of CoCrFeNi HEA present noticeable strain rate and strain sensitivity. This HEA shows exceptional resistance to dynamic shear failure, with an equivalent shear failure strain of about 173%. Microstructural examinations illustrate that the CoCrFeNi HEA fails by adiabatic shear banding. A comparison of dynamic shear flow responses of the CoCrFeNi HEA and eight different metals and alloys is made. This reveals the potential use of HEA in impact resistant applications in aerospace engineering and armour design. [ABSTRACT FROM AUTHOR]