The Experts below are selected from a list of 594 Experts worldwide ranked by ideXlab platform

F. Van Keulen - One of the best experts on this subject based on the ideXlab platform.

  • Sensitivity analysis of shape memory alloy shells
    Computers & Structures, 2008
    Co-Authors: Matthijs Langelaar, F. Van Keulen
    Abstract:

    This paper presents procedures for efficient design sensitivity analysis for shape memory alloy (SMA) structures modeled with shell Elements. Availability of sensitivity information at low computational cost can dramatically improve the efficiency of the optimization process, as it enables use of efficient gradient-based optimization algorithms. The formulation and computation of design sensitivities of SMA shell structures using the direct differentiation method is considered, in a steady state electro-thermo-mechanical Finite Element Context. Finite difference, semi-analytical and refined semi-analytical sensitivity analysis approaches are considered and compared in terms of efficiency, accuracy and implementation effort, based on a representative Finite Element model of a miniature SMA gripper. © 2007 Elsevier Ltd. All rights reserved.

Matthijs Langelaar - One of the best experts on this subject based on the ideXlab platform.

  • Sensitivity analysis of shape memory alloy shells
    Computers & Structures, 2008
    Co-Authors: Matthijs Langelaar, Fred Van Keulen
    Abstract:

    This paper presents procedures for efficient design sensitivity analysis for shape memory alloy (SMA) structures modeled with shell Elements. Availability of sensitivity information at low computational cost can dramatically improve the efficiency of the optimization process, as it enables use of efficient gradient-based optimization algorithms. The formulation and computation of design sensitivities of SMA shell structures using the direct differentiation method is considered, in a steady state electro-thermo-mechanical Finite Element Context. Finite difference, semi-analytical and refined semi-analytical sensitivity analysis approaches are considered and compared in terms of efficiency, accuracy and implementation effort, based on a representative Finite Element model of a miniature SMA gripper.

  • Sensitivity analysis of shape memory alloy shells
    Computers & Structures, 2008
    Co-Authors: Matthijs Langelaar, F. Van Keulen
    Abstract:

    This paper presents procedures for efficient design sensitivity analysis for shape memory alloy (SMA) structures modeled with shell Elements. Availability of sensitivity information at low computational cost can dramatically improve the efficiency of the optimization process, as it enables use of efficient gradient-based optimization algorithms. The formulation and computation of design sensitivities of SMA shell structures using the direct differentiation method is considered, in a steady state electro-thermo-mechanical Finite Element Context. Finite difference, semi-analytical and refined semi-analytical sensitivity analysis approaches are considered and compared in terms of efficiency, accuracy and implementation effort, based on a representative Finite Element model of a miniature SMA gripper. © 2007 Elsevier Ltd. All rights reserved.

F. Concha - One of the best experts on this subject based on the ideXlab platform.

Daniel Leidermark - One of the best experts on this subject based on the ideXlab platform.

  • Criteria evaluation for the transition of cracking modes in a single-crystal nickel-base superalloy
    Theoretical and Applied Fracture Mechanics, 2020
    Co-Authors: Christian Busse, Frans Palmert, Björn Sjödin, P. Almroth, David Gustafsson, Kjell Simonsson, Johan Moverare, Daniel Leidermark
    Abstract:

    Abstract Single-crystal nickel-base superalloys frequently experience two distinct fatigue crack growth modes. It has been observed that, under certain conditions, cracks transition from a path perpendicular to the loading direction to a crystallographic slip plane. As crystallographic cracking is associated with an increased fatigue crack growth rate, it is important to be able to predict when this transition occurs. In this work three different criteria for crystallographic cracking based on resolved anisotropic stress intensity factors are evaluated in a three-dimensional Finite Element Context. The criteria were calibrated and evaluated using isothermal fatigue experiments on two different specimen geometries. It is suggested by the results, that a threshold value of a resolved shear stress intensity factor can act as a conservative criterion indicating cracking mode transition. Further, a trend hinting towards a loading frequency dependency could be observed.

  • Evaluation of the crystallographic fatigue crack growth rate in a single-crystal nickel-base superalloy
    International Journal of Fatigue, 2019
    Co-Authors: Christian Busse, Frans Palmert, Björn Sjödin, P. Almroth, David Gustafsson, Kjell Simonsson, Daniel Leidermark
    Abstract:

    Abstract Cracks in single-crystal nickel-base superalloys have been observed to switch cracking mode from Mode I to crystallographic cracking. The crack propagation rate is usually higher on the crystallographic planes compared to Mode I, which is important to account for in crack growth life predictions. In this paper, a method to evaluate the crystallographic fatigue crack growth rate, based on a previously developed crystallographic crack driving force parameter, is presented. The crystallographic crack growth rate was determined by evaluating heat tints on the fracture surfaces of the test specimens from the experiments. Complicated crack geometries including multiple crystallographic crack fronts were modelled in a three dimensional Finite Element Context. The data points of the crystallographic fatigue crack growth rate collapse on a narrow scatter band for the crystallographic cracks indicating a correlation with the previously developed crystallographic crack driving force.

  • Prediction of crystallographic cracking planes in single-crystal nickel-base superalloys
    Engineering Fracture Mechanics, 2018
    Co-Authors: Christian Busse, Frans Palmert, Björn Sjödin, P. Almroth, David Gustafsson, Kjell Simonsson, Daniel Leidermark
    Abstract:

    Abstract The inherent anisotropy of single-crystal nickel-base superalloys brings many difficulties in terms of modelling, evaluation and prediction of fatigue crack growth. Two models to predict on which crystallographic plane cracking will occur is presented. The models are based on anisotropic stress intensity factors resolved on crystallographic slip planes calculated in a three-dimensional Finite-Element Context. The developed models have been compared to experiments on two different test specimen geometries. The results show that a correct prediction of the crystallographic cracking plane can be achieved. This knowledge is of great interest for the industry and academia to better understand and predict crack growth in single-crystal materials.

E. Ovalle - One of the best experts on this subject based on the ideXlab platform.