References of "Lengiewicz, Jakub 50031109"
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See detailBeam-inside-beam contact: Mechanical simulations of slender medical instruments inside the human body
Magliulo, Marco UL; Lengiewicz, Jakub UL; Zilian, Andreas UL et al

in Computer Methods and Programs in Biomedicine (in press)

Background and Objective. This contribution presents a rapid computational framework to mechanically simulate the insertion of a slender medical instrument in a tubular structure such as an artery, the ... [more ▼]

Background and Objective. This contribution presents a rapid computational framework to mechanically simulate the insertion of a slender medical instrument in a tubular structure such as an artery, the cochlea or another slender instrument. Methods. Beams are employed to rapidly simulate the mechanical behaviour of the medical instrument and the tubular structure. However, the framework’s novelty is its capability to handle the mechanical contact between an inner beam (representing the medical instrument) embedded in a hollow outer beam (representing the tubular structure). This "beam-insidebeam" contact framework, which forces two beams to remain embedded, is the first of its kind since existing contact frameworks for beams are "beam-to-beam" approaches, i.e. they repel beams from each other. Furthermore, we propose contact kinematics such that not only instruments and tubes with circular cross-sections can be considered, but also those with elliptical cross-sections. This provides flexibility for the optimization of patient-specific instruments. Results. The results demonstrate that the framework’s robustness is substantial, because only a few increments per simulation and a few iterations per increment are required, even though large deformations, large rotations and large curvature changes of both the instrument and tubular structure occur. The stability of the framework remains high even if the modulus of the inner tube is thousand times larger than that of the outer tube. A mesh convergence study furthermore exposes that a relatively small number of elements are required to accurately approach the reference solution. Conclusions. The framework’s high simulation speed originates from the exploitation of the rigidity of the beams’ cross-sections to quantify the exclusion between the inner and the hollow outer beam. This rigidity limits the accuracy of the framework at the same time, but this is unavoidable since simulation accuracy and simulation speed are two competing interests. Hence, the framework is particularly attractive if simulation speed is preferred over accuracy. [less ▲]

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See detailNon-localised contact between beams with circular and elliptical cross-sections
Magliulo, Marco UL; Lengiewicz, Jakub UL; Zilian, Andreas UL et al

in Computational Mechanics (in press)

The key novelty of this contribution is a dedicated technique to e fficiently determine the distance (gap) function between parallel or almost parallel beams with circular and elliptical cross-sections ... [more ▼]

The key novelty of this contribution is a dedicated technique to e fficiently determine the distance (gap) function between parallel or almost parallel beams with circular and elliptical cross-sections. The technique consists of parametrizing the surfaces of the two beams in contact, fixing a point on the centroid line of one of the beams and searching for a constrained minimum distance between the surfaces (two variants are investigated). The resulting unilateral (frictionless) contact condition is then enforced with the Penalty method, which introduces compliance to the, otherwise rigid, beams' cross-sections. Two contact integration schemes are considered: the conventional slave-master approach (which is biased as the contact virtual work is only integrated over the slave surface) and the so-called two-half-pass approach (which is unbiased as the contact virtual work is integrated over the two contacting surfaces). Details of the finite element formulation which is suitably implemented using Automatic Di fferentiation techniques are presented. A set of numerical experiments shows the overall performance of the framework and allows a quantitative comparison of the investigated variants. [less ▲]

Detailed reference viewed: 46 (8 UL)