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  • 1. Alsafadie, R.
    et al.
    Battini, Jean -Marc
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Somja, H.
    Hjiaj, M.
    Local formulation for elasto-plastic corotational thin-walled beams based on higher-order curvature terms2011In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 47, no 2, p. 119-128Article in journal (Refereed)
    Abstract [en]

    The paper deals with the derivation of a local elasto-plastic finite element formulation of three dimensional corotational beams with arbitrary cross- section. Based on Bernoulli beam kinematics, an improved displacement field is constructed by inclusion of second-order terms of cross-section local rotations. The formulation captures both the Saint-Venant and warping torsional effects of open cross sections. Numerical tests show that the inclusion of the second-order terms of the local bending curvatures gives more accurate and more efficient element that allows a significant reduction of the computational time.

  • 2.
    Brauer, Jesper
    KTH, Superseded Departments, Machine Design.
    A general finite element model of involute gears2004In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 40, no 13-14, p. 1857-1872Article in journal (Refereed)
    Abstract [en]

    Involute gears comprise primarily spur gears, helical gears, straight conical involute gears and conical involute gears. Robust and effective parameterised finite element models of involute gears should be based on analytically derived mathematical representations of their shape. In this paper we derive a mathematical description of conical involute gears that is also capable of representing three other types of involute gear. The equations and the intervals for the surface parameters are then used to create a general finite element model of involute gears.

  • 3.
    Brauer, Jesper
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Transmission error in anti-backlash conical involute gear transmissions: a global-local FE approach2005In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 41, no 5, p. 431-457Article in journal (Refereed)
    Abstract [en]

    This paper reports on a theoretical study of transmission errors in anti-backlash conical involute gear transmissions. Such transmissions are used to reduce or eliminate the backlash in mechatronic products such as industrial robots and thereby improving system stability. A global-local finite-element (FE) approach reduced the total computation time needed to solve the non-linear contact problems. This approach yields a dense FE mesh in the contact regions and a coarse mesh in the rest of the teeth.

  • 4.
    Chhang, Sophy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering. Université Bretagne, France.
    Battini, Jean Marc
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Hjiaj, M.
    Energy-momentum method for co-rotational plane beams: A comparative study of shear flexible formulations2017In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 134, p. 41-54Article in journal (Refereed)
    Abstract [en]

    This paper presents an energy-momentum method for three dynamic co-rotational formulations of shear flexible 2D beams. The classical midpoint rule is applied for both kinematic and strain quantities. Although the idea as such was developed in previous work, its realization and testing in the context of co-rotational Timoshenko 2D beam elements is done here for the first time. The main interest of the method is that the total energy and momenta are conserved. The three proposed formulations are based on the same co-rotational framework but they differ in the assumptions done to derive the local formulations. Four numerical applications are used to assess the accuracy and efficiency of each formulation. In particularly, the conservation of energy with a very large number of steps and the possibility to simplify the tangent dynamic matrix are investigated.

  • 5.
    Heng, Piseth
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Alhasawi, Anas
    Battini, Jean-Marc
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Hjiaj, Mohammed
    Co-rotating rigid beam with generalized plastic hinges for the nonlinear dynamic analysis of planar framed structures subjected to impact loading2017In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925Article in journal (Refereed)
  • 6.
    Le, Thanh-Nam
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Battini, Jean-Marc
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Hjiaj, Mohammed
    Dynamics of 3D beam elements in a corotational context: A comparative study of established and new formulations2012In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 61, p. 97-111Article in journal (Refereed)
    Abstract [en]

    This paper deals with Newmark time stepping methods and finite rotations for nonlinear finite element analysis of flexible beam structures. The corotational method is used to develop expressions of the internal forces and the corresponding tangent stiffness matrices. For the dynamic part, four formulations based on different parameterizations of rotations are compared. The first three are classic formulations taken from the literature with some modifications for two of them. The last one is new and uses three of the four Euler parameters (quaternion) as rotational variables. For all these approaches, theoretical derivations as well as practical implementations are given in detail. The similarities and differences between the formulations are pointed out. Six numerical examples are studied in order to compare these four formulations in terms of numerical accuracy and computational efficiency. Regarding efficiency, the choice of the predictor at each time step and the possibility to simplify the tangent inertia matrix are carefully investigated. The numerical results show that these four formulations have the same numerical accuracy, but that the computational efficiency depends on the choice of the tangent inertia matrix. Besides, the new formulation proposed in this paper turns out to be the fastest one.

  • 7.
    Nadampalli, Ravi V.
    et al.
    DAIMLER AG.
    Glandier, C.
    DAIMLER AG.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Implementing Linear Modelling of Interface Damping in a Finite Element SoftwareIn: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925Article in journal (Other academic)
    Abstract [en]

    In the automotive industry virtual modelling of losses in a built-up structure is still a challenge. A body-in-white car structure consists of many spot-welded parts and the modelling of their associated losses is highly interesting. For this purpose, the dissipation of mechanical energy is here modelled in the frame of large scale computations using linear techniques with commercially available finite element software. Mechanical, vibration damping is introduced through external forces which are pairwise applied such that they oppose the relative motion at the contact interfaces between two parts. Two aspects are investigated, first if the proposed modelling captures the main mechanisms of the damping on a system level. Second, if the predicted local vibration responses at different locations correlate well between predicted and previously measured (in vacuo) spectra. Initial simulations show promising results and the level of damping observed in the predictions are similar to the measured spectra, fo rvibration shapes which involve significant relative motion along the spot-welded surfaces. An advantage with this technique is that it helps in understanding of different sources of total system damping, i.e. due to material and other sources of damping. It is verified that non-material damping due to mechanical contact is a significant contributor to the losses in a built-up structure which may be simulated with the proposed technique. In the paper the overall approach is discussed together with the specific aspects of the finite element implementation technique proposed.

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