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Sandwich panel subjected to blast wave impact and accelerated fragments

Studziński Robert, Sumelka Wojciech, Malendowski Michał, Gajewski Tomasz, Al-Rifaie Hasan, Sielicki Piotr

Eksploatacja i Niezawodność

2024

Vol. 26, no. 2

art. no. 183698

The article presents sandwich panels subjected to blast wave impact and accelerated fragments. The research discusses results obtained from original experimental setups that fill a gap in the area of investigation of the mechanical response of sandwich panels used in civil engineering applications under accidental design situations such as blast wave impact and/or fragment penetration. In field experiments, a high-speed camera was used to record both the fragment trajectory and the deflection of the sandwich panel. The authors proposed the equivalent static load for both the global analysis of the sandwich panel and the calibration of the numerical model. In FE modelling, CONWEP algorithm was used to simulate blast wave impact, and ductile damage model material to allow perforation of the sandwich panel faces. The convergence of mesh size was analyzed. For the validated numerical model, an evaluation of the effect of the size of the fragment (diameter/mass) on the outlet velocity and the size of the inlet andoutlet holes was carried out.

Prediction of high-speed debris motion in the framework of time-fractional model: theory and validation

Malendowski Michał, Sumelka Wojciech, Gajewski Tomasz, Studziński Robert, Peksa Piotr, Sielicki Piotr W.

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 1

art. no. e46, 2023

In this work, a newly proposed fractional derivative framework is used for the prediction of high-speed debris motion. The paper focuses on the mathematical formulation of the equation of motion, in which the damping term is generalised using the fractional derivative. The capacity of the proposed approach to predict the motion of debris is justified by the experimental results. Furthermore, the mathematical formulation has been verified by extensive parametric studies on spherical projectiles. The general conclusion is that the elaborated formulation is more reliable compared to the classical approach or, in other words, the fractional viscous damping term (proportional to the fractional velocity of debris) provides a better description of the complexity of the real drag force.

Investigation of free vibration and buckling of Timoshenko nano-beam based on a general form of eringen theory using conformable fractional derivative and Galerkin method

Mohammadi Farogh Souf, Rahimi Zaher, Sumelka Wojciech, Yang Xiao-Jun

Engineering Transactions

2019

Vol. 67, iss. 3

347--367

The purpose of this paper is to study the free vibration and buckling of a Timoshenko nano-beam using the general form of the Eringen theory generalized based on the fractional derivatives. In this paper, using the conformable fractional derivative (CFD) definition the generalized form of the Eringen nonlocal theory (ENT) is used to consider the effects of integer and noninteger stress gradients in the constitutive relation and also to consider small-scale effect in the vibration of a Timoshenko nano-beam. The governing equation is solved by the Galerkin method. Free vibration and buckling of a Timoshenko simply supported (S) nano-beam is investigated, and the influence of the fractional and nonlocal parameters is shown on the frequency ratio and buckling ratio. In this sense, the obtained formulation allows for an easier mapping of experimental results on nano-beams. The new theory (fractional parameter) makes the modeling more flexible. The model can conclude all of the integer and non-integer operators and is not limited to the special operators such as ENT. In other words, it allows to use more sophisticated/flexible mathematics to model physical phenomena.