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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]

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]

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]

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]

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 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]

Creep is an irreversible time-dependent deformation in which a material under constant mechanical stress and elevated temperature for a considerably prolonged period of time, starts to undergo permanent deformation. Creep deformation occurs in three stages namely, primary, secondary and tertiary. Out of these three stages, secondary or steady state creep is particularly an area of engineering interest as it has almost a constant creep rate. Creep deformation plays a significant role in understanding effective service life of an engineering component working under high temperature conditions as such components such as super-heater and re-heater tubes and headers in a boiler, jet engines operating at temperature as high as 1200 ∘ C, usually experience a failure or rupture due to creep phenomenon. Design engineers keep a close attention on working stress conditions and elevated temperature under which an engineering component is expected to work as these conditions determine the onset of creep behavior in an engineering component. By recognizing the parameters of material response to creep behavior, engineers can analyse the useful service life and hazardous working conditions for an engineering components. Recognizing the creep phenomenon as high temperature design limitation, ASME Boiler and Pressure Vessel Code have provided guidelines on maximum allowable stresses for materials to be used in creep range. One of the criteria for determination of allowable stresses is 1% creep deformation of material in 100,000 h of service. Thus, the study of creep behavior in engineering components pertaining to high stress and temperature working conditions is very important as it affects the reliability and performance of the engineering components. The aim of our study is to understand the behavior of secondary creep deformation so that an advanced reinforced functionally graded material with better creep resistance, can be designed. In this paper, a secondary creep analysis of functionally graded (FG) thick-walled rotating cylinder under internal and external pressure is conducted. The novelty of the model intends to specify secondary creep stresses and strains by employing exponential, linear and quadratic volume reinforcement for S i C p ceramic in A l metal matrix in radial direction. This will help us to understand the effect of volume reinforcement in FG cylinder under internal/external pressure and rotating centrifugal body force by obtaining secondary creep stresses and strains. The response of the FG cylinder with isotropic material is analyzed and the solution for stress–strain rates in radial and tangential directions are obtained in closed form. Comparison of steady state creep stresses and strains under exponential, linear and quadratic volume reinforcement profiles are discussed and presented graphically. [ABSTRACT FROM AUTHOR]

• A comparison on mechanical models of TRISO fuel particle is performed. • The mechanical stress behavior of coating layer is further understood. • The particle failure probability is sensitive to mechanical models and material properties. TRISO fuel performance is crucial for the safety of High Temperature Gas-cooled Reactor (HTGR). In the engineering design process of HTR-PM by Institute of Nuclear and New Energy Technology (INET), PANAMA code was adopted to evaluate the mechanical performance and failure probability of TRISO coated particle fuels. However, PANAMA results are quite conservative compared with the recent HTR-PM fuel irradiation experiment. INET develops a new TRISO fuel performance code FRAT that employs more delicate models involving internal gas pressure buildup, mechanical stress analysis as well as temperature and burnup effects. In this paper, we use FRAT code and do a comparison study of mechanical analysis model of TRISO fuel particle. Results yield a high sensitivity of calculated TRISO fuel failure probability to mechanical models adopted in TRISO fuel performance. This work helps to further understand the mechanical models of TRISO fuel particle. [ABSTRACT FROM AUTHOR]

For industrial components such as pressure vessels and piping systems, it is important to determine the shakedown domains of structures under complex variable thermo-mechanical loads to avoid low cycle fatigue due to alternating plasticity or incremental plastic collapse caused by ratcheting. In this paper, the interaction among three common types of stresses are considered based on a plane model, namely, mechanical membrane stress, thermal membrane stress and thermal bending stress. Strict shakedown analysis is performed based on the Linear Matching Method under multiple variable mechanical and thermal loads. Three-dimensional shakedown domains for three types of modified Bree problems involving thermal membrane stress and generalized loading conditions are given for the first time, and the three-dimensional shakedown boundaries are expressed as two-dimensional parametric equations by introducing a new parameter called "secondary membrane bending ratio" R. By comparing the 3S criterion plane with the newly obtained 3D shakedown boundaries, the conservatism and non-conservatism of the 3S criterion are discussed under different loading paths. As an extension of the 3S criterion, a new and economical criterion on elastic shakedown assessment is proposed for generalized thermo-mechanical loading. The proposed shakedown boundary parametric equations and shakedown checking method can provide guidance for engineering design and safety assessment. • Shakedown boundaries and parametric equations are obtained for three types of modified Bree problems. • A new and complete elastic shakedown assessment method for generalized thermomechanical loading is proposed. • A new parameter called "secondary membrane bending ratio" R is introduced in shakedown analysis. • A detailed discussion on the non-conservatism of 3S criterion used for elastic shakedown analysis is made. • The connections among shakedown domains under three types of loading are constructed through the parameter R. [ABSTRACT FROM AUTHOR]

• Develop a kind of novel chain-soil interaction apparatus for measuring the chain axial resistance in sand. • Recommend the effective width parameter in sand for engineering design. • Propose a formula to predict the partial mobilization of soil resistance. For the mooring line embedded in seabed, the axial soil resistance directly affects the tension transfer characteristic along the mooring line. Effective width parameter E t was commonly adopted to assess the axial resistance of anchor chain. However, neither the chain axial resistance nor its effective width parameter in sand has been fully understood. In this two-part paper, a series of axial loading tests between chain and sand were conducted. Part I shows the monotonic loading results, and Part II aims to study the cyclic loading behavior. In Part I, a kind of novel chain-soil interaction apparatus was first developed, and the method for acquiring the axial resistance was proposed. On this basis, the influences of confining stress, chain nominal diameter, sand particle size and relative density were investigated in detail. It is found that when the chain axial resistance is fully mobilized, the effective width parameter in sand ranges from 8.91 to 11.94. The statistical average value E t =10.34 is quite close to the normalized chain perimeter P c =10.37(3.3π). Then, an example was given to show how to calculate the chain profiles in sand using the proposed E t expression. A method for calculating the chain profile in sands was verified by the centrifuge test results. The calculation results show that higher E t values lead to larger force inclined angles at the padeye. Under the condition, the anchor will suffer larger vertical loads due to the increase of the inclination angle. [ABSTRACT FROM AUTHOR]

The transfer joint is the key structurally functioning part of the transmission tower. The reliability of the transfer joint directly affects the stress and deformation characteristics of the whole tower structure. This paper studies experimentally and numerically the performance of a novel steel transfer joints formed with the integration of single- and double-angles respectively at the upper and lower parts of the connection. Two specimens with different sizes of gusset plates have been designed and tested with tensile loading. Moreover, finite element models have been constructed and validated with experimental findings for a detailed behavior analysis of yielding. The mechanical behavior in terms of stress distribution contours, deformation, yield locations, and failure mode of the gusseted steel joint has been evaluated. Combining observations made from simulation and test results, existing theoretical models for the design of the gusseted plate are discussed and improved. For engineering design convenience, the existing theoretical model is then updated to be experimentally-complying. • The performance of steel joints integrated with single and double-angles was studied. • Specimens with different sizes of gusset plates were tested with tensile loading. • Finite element models were constructed for a detailed behavior study of yielding. • The theoretical models of the gusseted plate are checked and improved. [ABSTRACT FROM AUTHOR]