Size does matter: further studies in hand–pack interaction using computer simulation

This study expands on a previous work by the authors where it was shown through the use of ethnography and finite element models that a link exists between the choice of grip and joint stresses. Further finite element models are created to investigate the relationship between joint stresses and hand dimensions. This is an important area of research for inclusive design, since some of the most vulnerable members of society, such as elderly women, often exhibit extremes of physical dimensions. Copyright © 2007 John Wiley & Sons, Ltd.     

‘Inclusive’ design for containers: improving openability

For many years the standard engineering design approach has been to design for the most common size or ability and hence ensuring that your product is applicable to the broadest proportion of society. Recently, however, this approach has been seen to be flawed, particularly with regards to consumer packaging (although there many examples in other industries, such as transport). This paper outlines a new approach to packaging design that has been termed ‘inclusive’ design. Copyright © 2005 John Wiley & Sons, Ltd.     

A finite element‐based approach for whole‐system simulation of packaging systems for their improved design and operation

The introduction of legislation to minimize packaging waste requires consumer goods manufacturers to use lighter‐weight materials and increase the use of recycled materials. This is demanding that machinery manufacturers provide highly flexible machines and tooling capable of handling these materials and new package designs. However, the ability of manufacturers to achieve this is all but prevented by a lack of fundamental understanding of machine–material interactions and an ability to generate such understanding. One way to overcome this is to use advanced simulation tools to represent the whole system including machine, process, materials and product. A finite element‐based simulation has been created to represent the in‐process behaviour of a packing system. The simulation focuses on the critical transition between flattened and erected states of a carton. In order to successfully simulate such a complex process, there are a number of major challenges concerning the representation of packaging materials and their properties, changing material behaviour during processing, machinery simulation and process modelling (simulating the interfacial interactions that take place during processing). The application of the whole‐system simulation for the purposes of improved design and operation are discussed with respect to four activities: design and set‐up of tooling, determination of optimal process settings, specification of material properties and the design of the pack. In all cases, a strong correlation was observed between the theoretical results and those obtained practically, thereby enabling quantitative understanding and quantitative rules to be generated. Copyright © 2009 John Wiley & Sons, Ltd.     

The use of uncertainty analysis for the design of container closures

Understanding how easy packaging is to open is becoming a major area of interest for the packaging industry. Designing packaging to meet the direct needs of the consumer has been termed ‘inclusive design’. However, there are differing parameters that may affect the ease of opening a product. This paper outlines how the use of uncertainty analysis coupled with ‘inclusive design’ techniques can help manufacturers understand which parameters are important for product ‘openability’. Copyright © 2006 John Wiley & Sons, Ltd.     

电子封装用环氧树脂固化温度与应变的三维有限元模拟

环氧树脂因具有许多优异的性能而被广泛用作电子封装材料,然而环氧树脂在固化过程中产生的内应力会对封装产品的性能产生严重影响。针对一种用于电子封装的环氧树脂,通过实验分析了其固化动力学、密度、导热系数、玻璃化转变温度、弹性模量、化学收缩应变和热应变等性能参数,建立了固化过程中的数学模型。通过ABAQUS建立三维有限元模型,采用顺序耦合分析方式,分步进行传热分析和应力应变分析,模拟环氧树脂固化过程中的温度场、固化度场和应力应变场。最后采用光纤布拉格光栅（FBG）监测环氧树脂在固化过程中内部的温度和应变变化,并与模拟进行对比,结果表明本文所建立的有限元模型具有较高的可靠性。      

Simulation and experiment of packaging of the fibre Bragg grating sensors using brazing/soldering methods

Abstract

To manufacture fibre Bragg grating (FBG) transducer, finite element model simulation and experimental verification of packaging of the FBG by brazing/soldering were investigated. The packaging processes and their impacts on the wavelength change of FBG were analysed. Simulation results showed that the Bragg wavelength of packaged FBG shifted down a level of ~10 nm. For experimental verification, temperature sensitivity of the packaged FBG was enhanced about twice of the bare FBG, while its spectrum was well preserved. The Bragg wavelength was shifted down a level of ~10 nm which was in accordance with the simulation.     

Critical Factors in Opening Pharmaceutical Packages: a Usability Study among Healthcare Workers,Women with Rheumatoid Arthritis and Elderly Women

This cross‐sectional study compared the usability of pharmaceutical packages to determine the critical factors involved in packages with different opening mechanisms. Four packaging types (a bottle with a screw cap, a box with a pill plate, disposable plastic droppers with a container and a jar with a hinge cap) were evaluated by 45 women (nurses, older women and women with rheumatoid arthritis). Usability was evaluated for subjective measures related to the ease of opening and for objective measures related to the time needed to open the packaging, electrical muscular activity (electromyography, EMG) and ranges of motion of the upper extremities. Of the arthritic women, 13% were unable to open the screw‐cap bottle, and 20% did not succeed in opening the plastic dropper packaging. Everyone else, except one older woman handling the plastic dropper packaging, managed to open all the packages. Regarding the ease of opening, the participants gave the plastic dropper packaging the lowest rating (p < 0.001). The arthritic women used greater relative biomechanical strain while opening the screw cap bottle and the box with pill plate compared with the other participants (p < 0.05), with the relative muscular strain in the forearm varying by 29–40% for the maximal EMG activity and the relative range of motion in the wrist being 70–90% of the maximal range of motion. These findings revealed both subjectively and objectively measured features on the usability of pharmaceutical packages. The comprehensibility of the opening mechanism and the ease of handling the package should be considered when user‐friendly products are being created. Copyright © 2013 John Wiley & Sons, Ltd.     

燃气灶无纸箱热收缩保护性包装结构设计与评价

目的 为打破家电泡沫加纸箱的传统包装形式,大胆创新设计无纸箱小家电燃气灶的热收缩包装,并使用CAE分析方法评价该包装的缓冲性能。方法 根据燃气灶产品特性设计缓冲衬垫结构,以热收缩膜直接紧紧包裹产品和缓冲衬垫的包装形式为评价对象,用Pro/E完成产品建模,导入Ansys Workbench完成跌落仿真分析,最后进行实验评价。结果 仿真结果表明,最大加速度出现在5.6 ms处,最大值为14.86g,小于产品脆值,仿真结果合格;跌落实验后,缓冲衬垫轻微变形,产品完好无破损,该包装方案可行。结论 验证了燃气灶无纸箱的热收缩包装的可靠性,为后续小家电的无纸箱包装提供了新思路。     

An ellipsoidal particle–finite element method for hypervelocity impact simulation

A number of coupled particle–element and hybrid particle–element methods have been developed for the simulation of hypervelocity impact problems to avoid certain disadvantages associated with the use of pure continuum‐based or pure particle‐based methods. To date these methods have employed spherical particles. In recent work a hybrid formulation has been extended to the ellipsoidal particle case. A model formulation approach based on Lagrange's equations, with particle entropies serving as generalized coordinates, avoids the angular momentum conservation problems which have been reported with ellipsoidal smooth particle hydrodynamics models. Copyright © 2003 John Wiley & Sons, Ltd.     

灶具包装设计及鼓包问题研究

目的设计一款缓冲包装,以解决在实际物流过程中出现的灶具包装鼓包问题。方法采用发泡聚苯乙烯(EPS)与天地盖纸箱相结合的方案对灶具包装进行优化设计;在AnsysWorkbench有限元软件中建立灶具、缓冲衬垫和瓦楞纸箱的有限元模型,通过有限元软件模拟灶具在运输、堆码过程中受压时纸箱的变形情况,并与试验结果进行对比;分析包装的缓冲效果,验证包装方案对产品鼓包的改善情况。结果在压板上施加11 kN压力后,旧方案纸箱整体最大变形量为19.78 mm,在z轴方向,纸箱最大变形量为3.79 mm,在x轴方向,纸箱最大变形量为2.57 mm。新方案纸箱整体最大变形量为9.17 mm,z方向最大变形量为0.50 mm,在x轴方向,纸箱最大变形量为0.32 mm,可见改善明显。玻璃面板、承液盘、底盘等易损部件的实际应力均小于许用应力,且新方案各部件的实际应力低于旧方案,与试验结果相符。结论新包装能够满足灶具在实际流通过程中的缓冲要求,并能有效改善产品鼓包情况。     

A rheological interface model and its space–time finite element formulation for fluid–structure interaction

This contribution discusses extended physical interface models for fluid–structure interaction problems and investigates their phenomenological effects on the behavior of coupled systems by numerical simulation. Besides the various types of friction at the fluid–structure interface the most interesting phenomena are related to effects due to additional interface stiffness and damping. The paper introduces extended models at the fluid–structure interface on the basis of rheological devices (Hooke, Newton, Kelvin, Maxwell, Zener). The interface is decomposed into a Lagrangian layer for the solid‐like part and an Eulerian layer for the fluid‐like part. The mechanical model for fluid–structure interaction is based on the equations of rigid body dynamics for the structural part and the incompressible Navier–Stokes equations for viscous flow. The resulting weighted residual form uses the interface velocity and interface tractions in both layers in addition to the field variables for fluid and structure. The weak formulation of the whole coupled system is discretized using space–time finite elements with a discontinuous Galerkin method for time‐integration leading to a monolithic algebraic system. The deforming fluid domain is taken into account by deformable space–time finite elements and a pseudo‐structure approach for mesh motion. The sensitivity of coupled systems to modification of the interface model and its parameters is investigated by numerical simulation of flow induced vibrations of a spring supported fluid‐immersed cylinder. It is shown that the presented rheological interface model allows to influence flow‐induced vibrations. Copyright © 2010 John Wiley & Sons, Ltd.     

Time‐domain soil–structure interaction analysis in two‐dimensional medium based on analytical frequency‐dependent infinite elements

A direct method for soil–structure interaction analysis in two‐dimensional medium is presented in time domain, which is based on the transformation of the analytical frequency‐dependent dynamic stiffness matrix. The present dynamic stiffness matrix for the far‐field region is constructed by assembling stiffness matrices of the analytical frequency‐dependent dynamic infinite elements, so that the equation of motion can be analytically transformed into the time‐domain equation. An efficient procedure is devised to evaluate the dynamic responses in time domain. Verification of the present formulation is carried out by comparing the compliances for a strip foundation on a homogeneous and layered half‐spaces with those obtained by other methods. Numerical analyses are also carried out for the transient responses of an elastic block and tunnel in a homogeneous and a layered half‐space. The comparisons with those by other approaches indicate that the proposed time‐domain method for soil–structure interaction analysis gives good solutions. Copyright © 2000 John Wiley & Sons, Ltd.     

Direct numerical simulation of saturated deformable porous media using parallel hybrid Lattice–Boltzmann and finite element method

Numerical techniques for modeling saturated deformable porous media have mainly been based on mixture theory or homogenization techniques. However, these techniques rely on phenomenological relationships for the constitutive equations along with assumptions of homogeneous and isotopic material properties to obtain closure. Direct numerical simulations of the multiphasic problem for flow in deformable porous media avoid such assumptions and thus can provide significantly accurate understanding of the physics involved. They serve as a tool to investigate the constitutive relationships in complex geometries. They also allow the validation of the existing mixture theory models and determine their limitations. In this work, a parallel hybrid method using Lattice Boltzmann Method (LBM) for fluid phase and Finite Element Method (FEM) for solid phase is used for direct numerical simulation of saturated deformable porous media. The method provides a number of unique features including scalability on distributed computing necessary for such a problem. The method has been validated for modeling fluid–structure interactions in complex geometries against a number of experimental and analytical solutions. Further some challenging problems has been chosen to show the capability of the method. Copyright © 2010 John Wiley & Sons, Ltd.     

Estimation of fixed charge density and diffusivity profiles in cartilage using contrast enhanced computer tomography

Contrast enhanced computer tomography (CT) imaging of articular cartilage has been proposed for diagnostics of cartilage degeneration, that is, osteoarthritis. Previous studies also indicate that acute cartilage damage can be detected by measuring diffusion of contrast agent into cartilage using CT. However, currently, there is no reliable method to measure spatial diffusion rates within cartilage tissue, and only average bulk values have been reported. In this paper, we develop a method to determine depthwise diffusivity of contrast agents in cartilage tissue using contrast enhanced CT. The triphasic mechano‐electrochemical theory of cartilage is modified to include diffusion of contrast agents. By applying statistical inversion theory and Bayesian approximation error approach, the method allows us to estimate a fixed charge density distribution in the cartilage tissue, an important determinant for mechanical competence of articular cartilage. The method is tested by using a one‐dimensional simulation study. Preliminary tests with experimental data on diffusion of anionic iodine contrast agent in bovine articular cartilage indicate that the method can provide realistic estimates for depth dependent fixed charge density. Thereby, the present study can improve our understanding on the feasibility of contrast enhanced CT for cartilage diagnostics. Copyright © 2014 John Wiley & Sons, Ltd.     

Implicit solid,flow and flow–solid finite element approaches in blade forging simulation

A comparative theoretical and numerical study of the flow (rigid‐plastic) and solid (elasto‐plastic, in rate form) simulation approaches applied to the isothermal blade forging process for closing and opening of the dies is presented. In the rigid‐plastic approach the solution is followed by an elasto‐plastic solution in unloading (opening of the dies). The deformation of the billet, effective plastic strains and stresses were compared between the two solutions in the closing of the dies and when the dies were opened. Furthermore, the flow–solid approach was used in simulating the process and then the results, including the time–load and time–volume curves, were compared with previous results. The cost was lower and the efficiency was superior in the suggested flow–solid approach. Copyright © 2003 John Wiley & Sons, Ltd.     

Adaptive finite element approximation of multiphysics problems: A fluid–structure interaction model problem

In this paper we consider finite element simulation of the mechanical response of an elastic solid immersed into a viscous incompressible fluid flow. For simplicity, we assume that the mechanics of the solid is governed by linear elasticity and the motion of the fluid by the Stokes equation. For this one‐way coupled multiphysics problem we derive an a posteriori error estimate using duality techniques. Based on the estimate we propose an adaptive algorithm that automatically constructs a suitable mesh for the fluid and solid computational domains given a specific goal quantity for the elastic problem. Copyright © 2010 John Wiley & Sons, Ltd.     

Ductile tearing simulation of Battelle pipe test using simplified stress‐modified fracture strain concept

In this paper, numerical ductile tearing simulation results are compared with six circumferential through‐wall and surface cracked pipes made of two materials (SA‐333 Gr. 6 and A106 Gr. B carbon steels), performed at Battelle. For simulation, a model using a simplified fracture strain model is employed, by analysing tensile data of the material. By comparing experimental J‐R data with FE simulation results, the damage model dependent on the element size is determined based on the ductility exhaustion concept. The model is used to simulate ductile tearing behaviour of six circumferential through‐wall and surface cracked pipes. In all cases, simulated results agree well with experimental load, crack length and crack mouth opening displacement versus load line displacement data.     

Converting a tetrahedral mesh to a prism–tetrahedral hybrid mesh for FEM accuracy and efficiency

This paper presents a computational method for converting a tetrahedral mesh to a prism–tetrahedral hybrid mesh for improved solution accuracy and computational efficiency of finite element analysis. The proposed method performs this conversion by inserting layers of prism elements and deleting tetrahedral elements in sweepable sub‐domains, in which cross‐sections remain topologically identical and geometrically similar along a certain sweeping path. The total number of finite elements is reduced because roughly three tetrahedral elements are converted to one prism element. The solution accuracy of the finite element analysis improves since a prism element yields a more accurate solution than a tetrahedral element due to the presence of higher‐order terms in the shape function. Only previously known method for creating such a prism–tetrahedral hybrid mesh was to manually decompose a target volume into sweepable and non‐sweepable sub‐volumes and mesh each of the sub‐volumes separately. Unlike the previous method, the proposed method starts from a cross‐section of a tetrahedral mesh and replaces the tetrahedral elements with layers of prism elements until prescribed quality criteria can no longer be satisfied. A series of computational fluid dynamics simulations and structural analyses have been conducted, and the results verified a better performance of prism–tetrahedral hybrid mesh. Copyright © 2009 John Wiley & Sons, Ltd.