Virtual Elements For Engineering Appications

• 2D VEM for crack-propagation

  Led by: F. Aldakheel, B. Hudobivnik, P. Wriggers

  Team: A. Hussein

  Year: 2018

  Funding: IRTG 1627
• Virtual element method (VEM) for phase-field modeling of brittle and ductile fracture

  Led by: F. Aldakheel, B. Hudobivnik, P. Wriggers

  Year: 2018

  Funding: DFG SPP 1748
• Virtual Element Method for Dynamic Applications

  The Virtual Element Method is a recent developed discretization method, which can be seen as an extension of the classical Galerkin finite element method. It has been applied to various engineering fields, such as elasto-plasticity, multiphysics, damage and fracture mechanics. This project focuses on the extension of VEM towards dynamic applications. In the first part the appropriate computation of the Massmatrix regarding the vitual element ansatzspace will be done. In future works, VEM will be applied to engineering problems, considering the dynamic behavior.

  Led by: F. Aldakheel, B. Hudobivnik, P. Wriggers

  Team: M. Cihan

  Year: 2019
• Virtual Element Method for 3D Contact

  Contact plays a very important role in engineering problems, where two or more bodies interact with each other through their surfaces. Many techniques were developed in the past, to formulate the contact constraint at the contact interface between two bodies. Nevertheless, VEM provides efficient and robust properties to enforce the contact constraint through the contact interface. Investigations in 2D have been done so far. This work aims an extensions of VEM to 3D contact problems.

  Led by: F. Aldakheel, B. Hudobivnik, P. Wriggers

  Team: M. Cihan

  Year: 2020

Phase Field Modeling of Fracture in Multi-Field Environments

• Water-induced damage mechanisms of cyclic loaded high-performance concretes

  Led by: P. Wriggers

  Team: F. Aldakheel

  Year: 2017

  Funding: DFG SPP 2020, erste Förderperiode

  Duration: 3 Jahre
• Virtual element method (VEM) for phase-field modeling of brittle and ductile fracture

  Led by: F. Aldakheel, B. Hudobivnik, P. Wriggers

  Year: 2018

  Funding: DFG SPP 1748

Multiscale and multiphysics material modelling of polycrystalline metals and forming processes

• Modelling and simulation of the joining zone during the tailored forming process

  In this project, micromechanically motivated thermo-chemo-mechanical material models are developed on a microscopic length scale and transformed to an effective macroscopic material model. In order to achieve a high mechanical strength of the hybrid solid component, these material models are used to evaluate the sensitivity of different process parameters after joining and during forming and heat treatment. Moreover, with aid of the the evaluation results the material behaviour of the joining zone can be accurately adjusted during the Tailored Forming process.

  Led by: F. Aldakheel, P. Wriggers

  Team: C. Böhm, F. Töller

  Year: 2019

  Funding: DFG im Rahmen des SFB 1153
• Water-induced damage mechanisms of cyclic loaded high-performance concretes

  The use of offshore wind energy is expanding and fatigue-loaded concrete structures are built that are submerged in water. This currently already applies to so-called grouted joints, where high-strength fine-grained concrete (grout) is used in the steel support structures of offshore wind turbines. Such constructions are subjected to several hundred million load cycles within their service life. An increased water content in the concrete results from the offshore exposure which is principally different to onshore constructions,. Comparatively few investigations of fatigue-tested concrete specimens immersed in water are documented in the literature. Despite the fact, that considerably scatterings occur in these results a clear tendency can be observed. Specimens that are immersed in water have a significantly lower fatigue resistance compared with specimens tested in air. Some investigations also show that fatigue-loaded concrete specimens immersed in water have a significant change in their fracture behaviour compared with specimens tested in air. This can be seen, in tests, for example, by ascending air bubbles, wash-outs of fine particles and premature crack initiation.Water-induced damage mechanisms in fatigue-loaded concrete have indeed been recognised in the past, but they were not identified and described with sufficient precision. Consequently, they cannot be quantified reliably. Based on the existing knowledge gap, the vast majority of these mechanisms have currently escaped numerical modelling and simulation.The aim of this research project is to understand, analyse and quantify macroscopically water-induced damage mechanisms of fatigue-loaded high-performance concretes in the Experimental-Virtual-Lab (EVL) with complementary very latest state-of-the-art experimental methods. At the same time, models will be created and numerically implemented on a micromechanical basis that enables proving of hypotheses that will be derived from the experimental investigations. The structural data serve for the validation of these models; the data will be determined by µCT scans, NMR measurements and mercury intrusion porosimetry.After a first clarification of the origin of mechanisms by the EVL, modelling at the macroscopic level will be attempted on the basis of the micromechanical investigations. In this way it will be verified, how the water influences the degradation behaviour of fatigue-loaded high-performance concretes and which additional active, water-induced damage mechanisms are decisively involved in the degradation process. It will be possible for the first time to carry out a prediction of the degradation behaviour of fatigue-loaded high-performance concretes immersed in water based on microstructurally orientated parameters.

  Led by: Fadi Aldakheel, Peter Wriggers

  Year: 2020

  Funding: DFG SPP 2020, zweite Förderperiode

  Duration: 3 Jahre