Re: Stationary Xfem Crack Abaqus Student
Boobieo Popo
I'm currently doing analysis of interlaminar crack growth in fibre-reinforced composite by Extended Finite Element Method (XFEM) using Abaqus. I'm a new Abaqus user and therefore I have to familiarise myself by constructing random 2D and 3D models with isotropic materials before jumping onto anisotropic.
Having gone through a few tutorials by Matthew Pais (thank you), I've managed to successfully model a 2D crack propagation model. The crack seems to propagate like I intended it to and it's all good. But applying the same approach to construct a 3D model, the crack remains stationary even with the increase in load magnitude. I've also tried lowering down the Max Principal stress as well as Fracture Energy under Traction-Separation setting but to no avail. I always ended up with the error "too many attempts made for this increment".
So my questions are, what causes the error and how do I fix it? Are there any additional steps required for 3D crack growth propagation compared to 2D? Apart from the magnitude of the load and the Max Principal stress, are there any other parameters governing crack initiation and propagation in Abaqus?
Am new to Abaqus and am experience convergence issues. i will be glad if you mail me a copy of the PDF file on how to improve convergence in XFEM (you mentioned above). obi...@hotmail.co.uk in my email i.d
I am facing convergence problems on abaqus using XFEM (with traction separation law property for the material) and Concrete Smeared Cracking (with traditional FEM). Both studies does not converge, this PDF you said is about improvement of the convergence only for XFEM, or is it more general? Could you please send this PDF file to the e-mail address: renanju...@hotmail.com ? It will be very helpful for my master science dissertation.
Thank you for taking time helping me with the problem. I'm not certain whether or not iMechanica allows one to post his/her email on the board itself so I sent you a message. Please do send me the PDF file as I'm sure it will be of a great help.
I am a new xfem abaqus , I thank you try define the type of growth as discrete crack propagation along arbitrary , solution-dependent path, and if you define the crack propagation direction , you can try .this is my own idea .
when i read ur problems i feel that mine is silly.i made a 2D crack propagation model using the XFEM. but the crack didn`t propagate .only there was a separation between the two surfaces the crac lie between. can anyone plz help me in knowing why this happened. and how can i have the crack tip propagates?
i saw a lot of research groups have their own codes, and make some improvements. so i wondered is there any problem that abaqus can not solve by XFEM, or the results can not satisfy the accuracy of research requirements.
For the first case, Maximum principle stress criterion has been used
and maximum principle stress has been set as 22e6. In result, in the
crack tip stress become about twice this maximum stress.But, no crack
has been initiated.
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In his current role, Colin Schwarz provides simulation-based risk assessment on narrow banded machinery noise with a strong focus on gearbox tonality. Together with colleagues, Colin sets up and validates processes based on multibody simulation, which supports such an assessment. Before joining GE Renewable Energies, Colin spent almost five years on the Simpack team of Dassault Systmes and covered topics like customer and project support, training, and product management. In parallel, Colin has been working on sophisticated wind turbine controllers, also called model predictive control. Besides real-time capabilities to provide a feasible control signal in time, topics like the controller impact on the drive train fatigue strength need to be adequately addressed.
The noise emission of wind turbines and farms can be an important and limiting factor for the acceptance and thus further growth of wind energy. Next to the overall noise emission level, tonal noise from machinery and drivetrain components can be disturbing contributions.
This presentation discusses the modeling of tonal noise contributions that are originated by gearbox teeth meshing, transmitted through complex, structure-borne transfer paths into the machine head, and radiated by tower and blade surfaces. A seamless tool chain of multibody simulation and boundary element method to solve the wave equation is a core feature to integrate such an approach for risk assessment and analysis into established design processes. Its reliability and uncertainty need to be understood very well to drive design decisions early in the design phases.
Zhiliang Xu is a Chief Dynamics Analysis Engineer at Goldwind Science Technology.
In the 10 years, he has mainly engaged in wind turbine dynamics simulation analysis, vibration stability evaluation, FEA, MDO, verification & validation.
Benjamin Marrant graduated as an aerospace engineer at Delft University of Technology in 2001. He worked as an associate researcher at Delft University of Technology in research projects related to the aeroelasticity of wind turbines until 2007. After that, Ben started in the Technology Division of Hansen Transmission, which ZF later acquired. In this division, he mainly worked in the area of NVH of multi-megawatt wind turbine gearboxes and drivetrains.
Title: An Automated Simulation Approach of Drivetrains towards Tonality Free Wind Turbines
As onshore wind turbines are installed closer and closer to urbanized areas, wind turbine OEMs are being faced with increasingly stringent noise regulations. Compliance with these noise regulations, combined with torque density increase measures, increasing power levels of onshore wind turbines, and shorter design cycles translate into ever-increasing design challenges for gearbox suppliers. As the major design levers with respect to NVH are being decided upon in the concept phase where not all design inputs are fixed it is key to be able to compare different concepts, gear designs, etc., and the interaction with the system level in a quick and easy way. This requires an all-in-one simulation approach, involving a.o. transfer path predictions with Simpack, which is able to predict the NVH risks for the different design options available. Therefore, ZF developed an integrated simulation platform that combines the different aspects of predicting wind turbine tonality. This enables ZF to develop NVH risk mitigation strategies pro-actively in an early phase of the design leading to less expensive and better integrated solutions.
Benedikt Michels has joined the DLR Institute for Flight Systems in 2016 as research assistant, after having obtained a Bachelor's degree in Mechanical Engineering and a Master's degree in Aerospace Engineering from the Technical University Braunschweig.
He has since been working on downwash models in the wind energy and helicopter research field and the VAST (and predecessor tools) development in general.
Since 2022, Benedikt leads the DLR-internal project "LAISA", which aims to develop more holistic simulation capabilities for wind farm aerodynamics and aeroacoustics on the one hand, and a more integrated design process for load adaptive rotor blades on the other hand.
The presentation gives a first overview of the emerging wind turbine simulation capabilities at the Institute of Flight Systems of the German Aerospace Center (DLR), using the multi-body system simulation tool Simpack combined with the in-house developed modular aeromechanics code VAST (versatile aeromechanics simulation tool).
Current activities focus on verification and validation, using a 2.3 MW NM80 wind turbine model from the DAN-AERO experiment.
The Simpack model of the turbine is set up by the DLR Institute of Aeroelasticity, using a python-written conversion suite to transfer the data provided in HAWC2 format into input for the Simpack Rotorblade Generator for the blades and directly create Simpack models for the other components, respectively.
To have at hand a more easily modifiable aerodynamic module in addition to the Simpack built-in FAST-AeroDyn, VAST is extended for wind turbine simulations. The coupling of VAST to Simpack via user-routine has already been developed in a previous joint project in the helicopter research field between DLR-FT and Dassault Systmes (VaMeSH).
Currently, VAST provides a blade element momentum theory (BEMT) and a free vortex-wake inflow model, both in combination with lookup table airfoil polars. Furthermore, a blade geometry model allows for freely configurable blade shapes. Other wind turbine-specific models cover the tower dam effect or the application of wind fields.
Initial simulations comparing the results with AeroDyn reference calculations have been carried out, showing very good agreement.
Lars Pilgaard MIKKELSEN has for the last 10 years been an Associate Professor in the Department of Wind Energy at the Technical University of Denmark. His work includes both teaching and research in the field of wind turbine blade materials. The research work Lars has been conducting over the last decade focuses on understanding mechanisms controlling the manufacturing, mechanical properties, and failure of the load-carrying laminates inside the wind turbine blades. A topic involving the use of Abaqus together with user-defined subroutines and advanced characterization technics such as fatigue testing and 3D x-ray tomography. The tomography, together with an advanced segmentation algorithm, aims to achieve precise numerical representations of the actual composite materials used in wind turbine blades. Lars joined the SIMULIA Champion program in 2020.
Starting his career as a consultant at BMW in Munich, Jochen worked for six years in the virtual design of acoustic and driving comfort, performing FEM and multi-body simulations of the drivetrain and complete vehicle.
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