Maschinendynamik

For dangerous goods packagings, drop testing onto an essential unyielding target can be used to assess the mechanical resistance to impact loads. Adopted regulations like Agreement concerning the International Carriage of Dangerous Goods by Road (ADR)/Regulation concerning the International Carriage of Dangerous Goods by Rail (RID) require that the impact surface provided shall be integral with a mass at least 50 times than that of the heaviest package to be tested. The problem is that many manufacturers do not possess impact targets that satisfy the required 50 times mass ratio for regulative drop tests during series production. The objective of this work is to verify existing and define improved criteria for impact target structures based on systematic investigations. Previous evidence highlights the relevance of other parameters in addition to the mass ratio. Therefore, in this research, a variation of drop test parameters was carried out experimentally. Furthermore, numerical vibration analysis was applied to investigate the deformability of the impact surface. The results conclude that the mass ratio of 1:50 cannot be defined as a decisive criterion. In order to determine the influence of further drop test parameters, the research findings were used to validate a parametric model that assesses impact target deflection. An approximation quality of over 90% was achieved. As a result, new evaluation criteria are proposed. First, a method for identifying critical impact target designs is provided. Second, a new comprehensive formula compares the approximated maximum deflection of a real impact target to the respective theoretical threshold derived from a worst‐case assumption. In practice, this leads to great advantages in the evaluation of already installed impact targets for dangerous goods packagings.

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“…The rigid body deflection as a function of time

d ((), t)

is described by Equation (3). 8

d ((), t) goodbreak= d_{0} e^{- ζ 2 {πf}_{0} t} italicsin ((), 2 {πf}_{0} \sqrt{1 - ζ^{2}} t) goodbreak= \frac{\overset{d}{true} ((), t goodbreak= t_{1})}{2 {πf}_{0} \sqrt{1 - ζ^{2}}} e^{- ζ 2 {πf}_{0} t} italicsin ((), 2 {πf}_{0} \sqrt{1 - ζ^{2}} t)

…”

Section: Methodsmentioning

confidence: 99%

Improved criteria for evaluating impact targets in regulative drop tests of dangerous goods packagings

et al. 2023

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“…For the initial boundary value problem of the bending deflection of parabolic type for the beam hinged on both ends the boundary conditions are w(x, t)| x=0 = 0, w(x, t)| x=l = 0, w ′′ (x, t)| x=0 = 0 , w ′′ (x, t)| x=l = 0 and homogeneous initial conditions are used. The general bending vibration solution is assumed as w(x, t) = j w j (x) α j (t) with orthogonal eigenfunctions w j (x) = W j sin j π x l , see [3] and [4], and the frequency of the excitation Ω j = j π c l depending on the axial speed c, see [5]. For the decoupled pure Saint-Venant-torsion the differential equation of hyperbolic type of the distortion φ x (x, t) is computed without constraining warping by defining the boundary conditions φ x (x, t) | x=0, x=l = 0 = 0 and also homogeneous initial conditions.…”

Section: Mechanical Model For Coupled Bending and Torsion Vibrationsmentioning

confidence: 99%

Efficient computation of coupled bending and torsion vibrations of slender structures with an axially moving eccentric load

Holl

Keplinger

2021

Proc Appl Math & Mech

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Frequently slender structures are excited by moving loads and show the corresponding transient vibrations. A model is derived using a simply supported Bernoulli-Euler beam and the coupled bending and torsion vibration equations are derived. An analytical solution of the decoupled partial differential equations is derived based on the eigenmode expansion considering the boundary and initial conditions. For the pure bending and the pure Saint-Venant torsion the analysis is performed and the beam vibrations are calculated. The coupled bending and torsion deformations are computed using a modal transformation, where it is essential that the eigenmodes are the same for both kinds of vibrations. The resulting modal decoupling yields two separated ordinary differential equations in time with the assumed constant velocity of the axially moving excitation load. Closed form solutions are used which show a very good convergence. A transformation into the original coordinates results in the solutions of the coupled equations. The results are plotted in a dimensionless form. The evaluation and comparison with a suitable numerical calculation using a finite element model shows a good agreement of the results. It turns out that a fine discretization is necessary and the computation effort for computing the transient dynamic solution is very much higher.

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“…1). The knowledge of the kinematic parameters in two positions gives sufficient notions about the dynamic system behaviour of the welding manipulator [1].…”

Section: Measurementmentioning

confidence: 99%

Identification and Verification of Dynamic Parameters for the Welding Manipulator

Jírová¹,

Pešík²

2020

SJSUT.ST

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Maschinendynamik

Cited by 22 publications

References 0 publications

Improved criteria for evaluating impact targets in regulative drop tests of dangerous goods packagings

Improved criteria for evaluating impact targets in regulative drop tests of dangerous goods packagings

Efficient computation of coupled bending and torsion vibrations of slender structures with an axially moving eccentric load

Identification and Verification of Dynamic Parameters for the Welding Manipulator

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