FEM

FEM
  • 文章类型: Journal Article
    扩展有限元方法(XFEM)是结构力学的有力工具,帮助工程师和设计师了解材料结构如何响应应力,从而帮助创建机械改进的结构。XFEM方法揭示了生物和工程材料中材料拓扑结构与断裂行为之间的非凡关系,增强特殊的断裂增韧机制,如裂纹偏转和制动。尽管它广泛使用,非常需要对涉及XFEM的案例研究进行详细修订,重点是应用而不是数值建模方法。在这次审查中,介绍了XFEM,并将其与轮廓积分法等其他计算断裂模型进行了简要比较,虚拟裂纹闭合技术,内聚区模型,和相场模型,突出方法的利弊(例如,数值收敛,商业软件实施,预设的裂纹参数,和计算速度)。演示和讨论了XFEM在材料设计中的使用,重点介绍复合材料以及生物和生物材料的最新研究,还简要介绍了其在其他领域的应用。这篇综述最后讨论了XFEM的缺点,并概述了该方法在应用材料科学研究中的未来前景,例如XFEM和人工智能技术的融合。
    The eXtended finite element method (XFEM) is a powerful tool for structural mechanics, assisting engineers and designers in understanding how a material architecture responds to stresses and consequently assisting the creation of mechanically improved structures. The XFEM method has unraveled the extraordinary relationships between material topology and fracture behavior in biological and engineered materials, enhancing peculiar fracture toughening mechanisms, such as crack deflection and arrest. Despite its extensive use, a detailed revision of case studies involving XFEM with a focus on the applications rather than the method of numerical modeling is in great need. In this review, XFEM is introduced and briefly compared to other computational fracture models such as the contour integral method, virtual crack closing technique, cohesive zone model, and phase-field model, highlighting the pros and cons of the methods (e.g., numerical convergence, commercial software implementation, pre-set of crack parameters, and calculation speed). The use of XFEM in material design is demonstrated and discussed, focusing on presenting the current research on composites and biological and bioinspired materials, but also briefly introducing its application to other fields. This review concludes with a discussion of the XFEM drawbacks and provides an overview of the future perspectives of this method in applied material science research, such as the merging of XFEM and artificial intelligence techniques.
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  • 文章类型: Journal Article
    本文的目的是回顾有限元方法(FEM)在楔横轧(CWR)建模中的应用。CWR是一种制造工艺,用于生产阶梯轴和轴以及锻造零件,以便在锻压机上进一步加工。尽管CWR的概念是在140年前发展起来的,直到第二次世界大战后才在工业中使用。这是由于与楔形工具设计相关的限制以及其构造的高成本。因此,直到二十世纪末,CWR工具是由轧机制造商制造的,因为他们雇用了在CWR工艺设计方面具有丰富经验的工程师。直到FEM广泛用于CWR分析时,这种情况才发生了变化。近年来开展了大量的理论研究,他们的发现在这篇综述文章中描述。本文介绍了有效应用有限元法的九个研究领域,即:应力和应变状态;力参数;CWR中的破坏模式;材料断裂;微观结构建模;工件端部凹陷的形成;空心零件的CWR形成;有色金属材料零件的CWR形成;和新的CWR方法。最后,为了展示FEM在CWR建模中的潜力,数值模拟了制造汽车变速箱中使用的阶梯轴的CWR工艺。该数值模拟实例表明,FEM可以用于对复杂的CWR情况进行建模,这将导致未来对这种先进制造技术的兴趣与日俱增。
    The aim of this article is to review the application of the finite element method (FEM) to cross-wedge rolling (CWR) modeling. CWR is a manufacturing process which is used to produce stepped axles and shafts as well as forged parts for further processing on forging presses. Although the concept of CWR was developed 140 years ago, it was not used in industry until after World War 2. This was due to the limitations connected with wedge tool design and the high costs of their construction. As a result, until the end of the twentieth century, CWR tools were constructed by rolling mill manufacturers as they employed engineers with the most considerable experience in CWR process design. The situation has only changed recently when FEM became widely used in CWR analysis. A vast number of theoretical studies have been carried out in recent years, and their findings are described in this overview article. This paper describes nine research areas in which FEM is effectively applied, namely: the states of stress and strain; force parameters; failure modes in CWR; material fracture; microstructure modeling; the formation of concavities on the workpiece ends; CWR formation of hollow parts; CWR formation of parts made of non-ferrous materials; and new CWR methods. Finally, to show the potential of FEM on CWR modeling, a CWR process for manufacturing a stepped shaft used in car gearboxes is simulated numerically. This numerical simulation example shows that FEM can be used to model very complex cases of CWR, which should lead to a growing interest in this advanced manufacturing technique in the future.
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  • 文章类型: Journal Article
    纤维增强聚合物(FRP)在增强木结构中的应用已证明其在增强承载能力方面的效率,在某些情况下,结构元件的刚度,从而在新设计和改造现有历史建筑方面提供具有成本效益和竞争力的替代方案。在过去的几十年里,几种增强材料和技术的发展,在数值模拟方面取得了相当大的进展,特别是使用有限元方法。随着这一研究领域的广泛和多样化,以及出现了许多矛盾的结果,彻底的审查是必要的。这份手稿涵盖了历史预赛的主题,用碳和玻璃纤维复合材料增强,键特性,主要加固技术,打结的造型,以及纤维波纹度对复合材料性能的影响。详细介绍了加固梁力学的实验和数值研究。提供了一个独一无二的表格,该表格将在几项研究中观察到的刚度改善与分析估计进行了比较。提请注意已经出现的一些挑战,例如,适度的刚度增强,复合材料-木材界面,打结的造型,和加强有缺陷的木材构件。本文可作为今后研究和工程项目的出发点。
    The application of fibre-reinforced polymers (FRP) for strengthening timber structures has proven its efficiency in enhancing load-bearing capacity and, in some cases, the stiffness of structural elements, thus providing cost-effective and competitive alternatives both in new design and retrofitting existing historical buildings. Over the last few decades, several reinforcing materials and techniques evolved, and considerable progress was made in numerical modelling, especially using the finite element method. As this field of research has become extensive and diversified, as well as numerous contradicting results have emerged, a thorough review is necessary. This manuscript covers the topics of historical preliminaries, reinforcing with carbon and glass fibre composites, bond characteristics, main reinforcing techniques, modelling of knots, and the effects of the fibre waviness on the composite behaviour. A detailed overview is given on the experimental and numerical investigation of mechanics of strengthened beams. A one-of-a-kind table is presented that compares the stiffness improvement observed in several studies with analytical estimates. Attention is drawn to a number of challenges that have arisen, e.g., the moderate stiffness enhancement, composite-to-wood interface, modelling of knots, and strengthening of defected timber members. This paper can be used as a starting point for future research and engineering projects.
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  • 文章类型: Journal Article
    由于病理和超生理机制导致的非结缔组织和结缔组织软组织的损伤和破裂的计算模型对于对失败的基本理解至关重要。软组织损伤模型的最新进展在开发人造组织中起着至关重要的作用。医疗器械/植入物,和手术干预实践。本文回顾了最近开发的损伤模型和破裂模型,这些模型考虑了组织的微观结构。先前的审查工作分别显示了损坏和破裂,其中这项工作回顾了软组织的损伤和破裂。其中,本文详细介绍了软组织损伤演化和撕裂的各种模型,重点介绍了关键的概念思想,优势,局限性,和挑战。本文概述了损伤和破裂模型的一些关键挑战,这有助于将目前的损伤和破裂模型扩展到各种软组织。
    Computational modelling of damage and rupture of non-connective and connective soft tissues due to pathological and supra-physiological mechanisms is vital in the fundamental understanding of failures. Recent advancements in soft tissue damage models play an essential role in developing artificial tissues, medical devices/implants, and surgical intervention practices. The current article reviews the recently developed damage models and rupture models that considered the microstructure of the tissues. Earlier review works presented damage and rupture separately, wherein this work reviews both damage and rupture in soft tissues. Wherein the present article provides a detailed review of various models on the damage evolution and tear in soft tissues focusing on key conceptual ideas, advantages, limitations, and challenges. Some key challenges of damage and rupture models are outlined in the article, which helps extend the present damage and rupture models to various soft tissues.
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  • 文章类型: Journal Article
    简介:生物可降解材料一直处于尖端研究的最前沿,并为生物医学工程中的骨植入物的设计和制造提供了真正可行的选择。关于这些材料的大多数研究都集中在其相对于不可生物降解(NB)材料的生物学特性和力学行为上;但是可生物降解的骨植入物的设计方面和参数配置在某种程度上并没有受到应有的关注。涵盖的领域:这篇综述旨在深入了解可生物降解的骨植入物的参数概念化设计,并充分考虑了骨-可生物降解的植入物界面(BBII)的特征,常规使用的骨植入物的设计技术,以使用标准测试方法优化参数,传统设计,以及植入物和愈合行为的有限元分析方法,制造技术,实时手术模拟,等等。专家意见:一些成功和常规使用的NB骨植入物不会随着时间的推移而溶解或降解,需要在达到预期目标后通过复杂的手术移除。这些骨植入物应重新概念化并设计有适当的可生物降解材料,同时适当注意所涉及的所有因素/参数,并在这些因素之间取得平衡,最终目标是满足所有期望的矫形要求。
    Introduction: Biodegradable materials have been at the forefront of cutting-edge research and offer a truly viable option in the designing and manufacturing of bone implants in biomedical engineering. Most research regarding these materials has focused on their biological characteristics and mechanical behavior vis-à-vis nonbiodegradable (NB) materials; but the design aspects and parametric configurations of biodegradable bone implant have somehow not received as much attention as they deserved.Area covered: This review aims to develop insight into the parametrically conceptualized design of biodegradable bone implant and takes into due consideration the characteristics of bone-biodegradable implant interface (BBII), design techniques employed for conventionally used bone implants to optimize parameters using standard test methods, traditional design, and finite element analysis approaches for implant and healing behavior, manufacturing techniques, real-time surgical simulations, and so on.Expert opinion: Some successful and conventionally used NB bone implants do not dissolve or degrade with time and require removal through a complicated surgery after fulfilling the intended objectives. These bone implants should be reconceptualized and designed with an appropriate biodegradable material while paying due attention to all factors/parameters involved and striking a balance between these factors with the ultimate objective of fulfilling all desired orthopedic requirements.
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  • 文章类型: Journal Article
    FEM was technologically innovated which initially aimed at answering structural analysis difficulties involving Mechanics, Civil and Aeronautical Engineering. FEM basically stands for a numerical model of analyzing stresses as well as distortions in the form of any agreed geometry. There for the shape is discretized into the so-called \'finite elements\' coupled through nodes. Accuracy of the results is determined by type, planning and total number of elements used for a particular study model. 3-D FE model was designed for in-depth qualitative examination of the relations amongst implant, tooth, periodontal ligament, and bone. Scholarly work equating work reliability, validated with a 3-D modeling suggested that meticulous data can be acquired with respect to stress distribution in bone. Comparative results from 3-D FEA studies showed that 3D FEA, when matched with in-vivo strain gauge measurements were corresponding with clinical outcomes. The aim of this review of literature is to provide an overview to show the application of FEM in (Short) implant dentistry.
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