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Finite Element Method

Jinxiong Zhou's picture

A mesoscale computational approach to predict ABD matrix of thin woven composites

The ABD matrix is a fundamental method to characterize the overall stiffness behavior of laminated composite structures. Although classical laminate theory has been widely used, it has limitations in predicting the ABD matrix for woven composites. To address this issue, this paper presents a mesoscale homogenization approach aimed at computing the ABD matrix for thin woven composites accurately. The mesoscale representative volume element (RVE) of the woven composite is generated using TexGen and imposed with periodic boundary conditions to enforce the Kirchhoff thin plate assumption.

jfmolinari's picture

Journal club for December 2023 : Recent trends in modeling of asperity-level wear

Ernest Rabinowicz’s words, spoken two decades ago in his groundbreaking textbook on the friction and wear of materials [1], continue to resonate today: ’Although wear is an important topic, it has never received the attention it deserves.’ Rabinowicz’s work laid the foundation for contemporary tribology research [2]. Wear, characterized as the removal and deformation of material on a surface due to the mechanical action of another surface, carries significant consequences for the economy, sustainability, and poses health hazards through the emission of small particles. According to some estimates [1, 3], the economic impact is substantial, accounting for approximately 5% of the Gross National Product (GNP).

Despite its paramount importance, scientists and engineers often shy away from wear analysis due to the intricate nature of the underlying processes. Wear is often perceived as a ”dirty” topic, and with good reason. It manifests in various forms, each with its own intricacies, arising from complex chemical and physical processes. These processes unfold at different stages, creating a time-dependent phenomenon influenced by key parameters such as sliding velocity, ambient or local temperature, mechanical loads, and chemical reactions in the presence of foreign atoms or humidity.

The review paper by Vakis et al. [5] provides a broad perspective on the complexity of tribology problems. This complexity has led to numerous isolated studies focusing on specific wear mechanisms or processes. The proliferation of empirical wear models in engineering has resulted in an abundance of model variables and fit coefficients [6], attempting to capture the intricacies of experimental data.

Tribology faces a fundamental challenge due to the multitude of interconnected scales. Surfaces exhibit roughness with asperities occurring at various wavelengths. Only a small fraction of these asperities come into contact, and an even smaller fraction produces wear debris. The reasons behind why, how, and when this occurs are not fully understood. The debris gradually alter the surface profile and interacts with one another, either being evacuated from the contact interface or gripping it, leading to severe wear. Due to this challenge of scales, contributions of numerical studies in wear research over the past decades sum up to less than 1% (see Fig. 1). Yet, exciting opportunities exist for modeling, which we attempt to discuss here.

While analyzing a single asperity contact may not unveil the entire story, it arguably represents the most fundamental level to comprehend wear processes. This blog entry seeks to encapsulate the authors’ perspective on this rapidly evolving topic. Acknowledging its inherent bias, the aim is to spark controversies and discussions that contribute to a vibrant blogosphere on the mechanics of the process.

The subsequent section delves into the authors’ endeavors in modeling adhesive wear at the asperity level. Section 3 navigates the transition to abrasive wear, while Section 4 explores opportunities for upscaling asperity-level mechanisms to the meso-scale, with the aspiration of constructing predictive models. Lastly, although the primary focus of this blog entry is on modeling efforts, it would be remiss not to mention a few recent advances on the experimental front.

Jinxiong Zhou's picture

Surrogate Modeling Accelerated Shape Optimization of Deployable Composite Tape-Spring Hinges

Composite tape-spring hinge (CTSH) is a simple yet elegant mechanical component for various deployable space structures. This paper formulates and addresses cut-out shape optimization of a CTSH, which is seldom touched upon in literature. Both the maximum strain energy stored during the folding process as well as the maximum bending moment during deployment were maximized in a concurrent way, and the multi-objective optimization problem was realized by merging data-driven surrogate modeling and shape optimization.

PhD vacancy (4 years) on computational mechanics of thick adhesive joints in large wind turbine blades

Over the last years, UGent-MMS has developed the stand-alone BladeMesher software for generating finite element models of large wind turbine blades. The software reads in the material data and airfoil data of the wind turbine blade, and automatically constructs the geometry and finite element mesh for the blade. In a next step, the nodal and element information of the finite element mesh is written out to an input file for a commercial finite element solver (Abaqus in this case).

Postdoc vacancy (2.5 years) on multi-scale modelling of fatigue in 3D printed metals

The use of 3D printed metal structures is taking a very fast ramp-up in industry. General Electric has demonstrated the possibility of printing titanium fuel injectors for their LEAP engine, EADS has printed a nacelle hinge bracket for the Airbus A320, Boeing is printing plastic inlet ducts for high-altitude aircrafts, hip implants and other prosthetics are exploiting the design freedom of additive manufacturing (AM),...

mohammedlamine's picture

Scientific Paper

Hi All,

Please Find in this Post my Scientific Paper :

Numerical Analysis of Damage Zones in a Bridge

Mohammed Lamine MOUSSAOUI , Mohamed CHABAAT

International Journal of Structural Integrity, Emerald Publishing,

Volume 11, No. 1, pp. 1-12, 2020

Doi: https://doi.org/10.1108/IJSI-03-2019-0017

 

Best Regards

Ajeet Kumar's picture

A finite element formuation for a direct approach to elastoplasticity in special Cosserat rods

A finite element formulation is presented for a direct approach to model elastoplastic deformation in slender bodies using the special Cosserat rod theory. The direct theory has additional plastic strain and hardening variables, which are functions of just the rod's arc-length, to account for plastic deformation of the rod. Furthermore, the theory assumes the existence of an effective yield function in terms of stress resultants, i.e., force and moment in the cross-section and cross-section averaged hardening parameters.

1d finite element beam modelling for pipe

Choose a channel featured in the header of iMechanica: 

HI , the query is related to FE modelling of 1d Euler bernouli beam for pipe

If a pipe is modeled as a beam ,how can we input or account for the internal pressure of pipe. 

What is the quantity and the direction of nodal loads

Should a load = Pressure x Pipe sec Area be applied to all nodes??

Thank You.

 

PhD vacancy (4 years) on topology optimization of large 3D printed structures with functionally graded materials

Arc welding based additive manufacturing or WAAM techniques are attracting interest from the manufacturing industry because of their potential to fabricate large metal components with low cost and short production lead time. This process exists alongside other high deposition rate metal AM technologies such as powder and wire based DED. While these use either laser or an electron beam as energy source to melt a metal powder or wire, WAAM technologies melt metal wire using an electric arc.

PhD/postdoc vacancy (4 years) on computational mechanics of large wind turbine blades

Over the last years, UGent-MMS has developed the stand-alone BladeMesher software for generating finite element models of large wind turbine blades. The software reads in the material data and airfoil data of the wind turbine blade, and automatically constructs the geometry and finite element mesh for the blade. In a next step, the nodal and element information of the finite element mesh is written out to an input file for a commercial finite element solver (Abaqus in this case).

Postdoc in Micromagnetics at Aarhus University

Candidates with a strong background in micromagnetics are invited for a 1-year postdoctoral position. The position may be extended up to 6 months. The position is part of the MAGFLY project, which is focused on the development of flywheels using iron-oxide magnets. The position is theoretical/computational and focuses on the modeling and simulation of the microstructure of magnetic materials to predict macroscopic magnetic properties, in close collaboration with the experimental groups of the MAGFLY project.

zichen's picture

A Remotely Controlled Transformable Soft Robot Based on Engineered Cardiac Tissue Construct

Many living organisms undergo conspicuous or abrupt changes in body structure, which is often accompanied by a behavioral change. Inspired by the natural metamorphosis, robotic systems can be designed as reconfigurable to be multifunctional. Here, a tissue-engineered transformable robot is developed, which can be remotely controlled to assume different mechanical structures for switching locomotive function.

Urgent: 2 fully-funded PhD theses at Synopsis (Exeter) / Cardiff University / University of Luxembourg in machine learning/biomedical simulations/3D medical image processing

Synopsys NE Ltd (https://www.synopsys.com/simpleware.html), Cardiff University and University of Luxembourg invites applications for 2 Early Stage Researcher position (Doctoral Candidate) as part of the Rapid Biomechanics and Simulation for Personalized Clinical Design (RAINBOW) MCSA European Training Network. RAINBOW is funded under the European Union’s Horizon 2020 research and innovation program.
 

Postdoctoral vacancy (3 years) on patient-specific design and finite element modelling of 3D printed medical implants

3D printing or Additive Manufacturing (AM) technologies carry the promise of revolutionizing the quality and efficiency of healthcare. However, the required technologies, even when available, are currently too fragmented to be integrated into routine, affordable and streamlined solutions that can benefit a large number of patients. The challenge thereby is to deliver 3D printing technologies that enable:

rabedi's picture

PhD position on computational mechanics (preferably with solid mechanics focus)

Hello,

I have a PhD position available for a project titled " Asynchronous, Parallel-Adaptive Solution of Extreme Multiscale Problems in Seismology" funded by the U.S. National Science Foundation (NSF). The graduate research assistantship (GRA) position is for the University of Tennessee Space Institute (UTSI) which is a part of University of Tennessee Knoxville (UTK).

This project is conducted in collaboration with the University of Illinois at Urabana-Champaign (UIUC). Some of the main components of this project are,

M.S./Ph.D. position in Computational Mechanics and Materials at University of Massachusetts Dartmouth

Applications are invited for an M.S./Ph.D. position in Computational Mechanics and Materials at the Department of Mechanical Engineering at University of Massachusetts Dartmouth. The ideal candidate should have a B.S. in engineering, math or physics, with prior experience in continuum mechanics, computational modeling, and/or finite element analysis. The position will start in Fall 2017.

Emilio Martínez Pañeda's picture

Damage modeling in Small Punch Test specimens

I hope some of you may find this work interesting:

Damage modeling in Small Punch Test specimens

E. Martínez-Pañeda, I.I. Cuesta, I. Peñuelas, A. Díaz, J.M. Alegre

Theoretical and Applied Fracture Mechanics, 86A, pp. 51-60

http://www.sciencedirect.com/science/article/pii/S0167844216301616

A pre-print is available at www.empaneda.com

alicia's picture

Multiple postdoc openings at UC San Diego (USA) and Cardiff University (UK)

Applications are invited from highly motivated researchers for two postdoctoral positions immediately available in the Multiscale Multiphysics Design Optimisation (M2DO) lab, led by H Alicia Kim.

Jinxiong Zhou's picture

Predicting origami-inspired programmable self-folding of hydrogel trilayers

Imitating origami principles in active or programmable materials opens the door for development
of origami-inspired self-folding structures for not only aesthetic but also functional purposes. A
variety of programmable materials enabled self-folding structures have been demonstrated across
various fields and scales. These folding structures have finite thickness and the mechanical
properties of the active materials dictate the folding process. Yet formalizing the use of origami

Arttu Polojärvi's picture

Doctoral Candidate Position in Computational Ice Mechanics

We are looking for a doctoral student to join our Arctic Marine and Ice Technology research group at the Aalto University (Finland), Department of Mechanical Engineering, to study ice-structure interaction process in shallow water using numerical simulations.  In the complex ice-structure interaction process an intact ice sheet fails into discrete ice blocks, which affect further stages of the process. Realistic calculations of ice loads due to this process require modeling of the ice blocks and their pile-up process.

Yield behaviour of trabecular bone

A recently published paper  "Evaluating the macroscopic yield behaviour of trabecular bone using a nonlinear homogenisation approach" links the micromechanics of bone to its macroscopic behaviour. The paper may be of interest to colleagues on this forum. The abstract is provided below.

Abstract:

PhD Vacancy: UK Centre for Doctoral Training in Fusion Energy

I am currently looking to fill an open PhD position in a project titled:

Advanced Virtual Design of 3D Printed Fusion Reactor Components

This is to continue recent work that uses X-ray tomography, high performance computing and finite element analysis to design the plasma facing wall of the ITER reactor. Recent related publications can be found below:

PhD in Biomaterials for Aerospace Composites

Applications are invited for a fully funded PhD studentship at the University of Manchester to help develop the next generation of simulation tools. These will be used to evaluate the structural integrity of novel aerospace composites under a wide range of operational conditions.

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