A Vibro-Impacting Model for the Detection of Delamination

Konyukhov

Vielsack

et al. 2005

Engineering Structures

Impacts in forced dynamic systems lead to non-smooth vibrations, showing a scenario of bifurcations. Mechanical and numerical modelling is known for rigid body systems with distinct points of contact. In contrast, continuous systems can have a line of possible contact. As an example a vibrating beam with a delaminated layer will be considered. The objective is to establish a finite element formulation for stationary nonlinear oscillation arising from the evolution of impacts along the contact line between the delaminated layer and the remaining beam. The objectives are focussed on the choice of the unknown values of a set of parameters that mainly describe energy dissipation. A calibration of these parameters can be achieved by experimental results and by investigation of a minimal mechanical model.

Section: Minimal Modelmentioning

confidence: 99%

Parameter estimation for finite element analyses of stationary oscillations of a vibro-impacting system

Konyukhov

Vielsack

et al. 2005

Engineering Structures

“…Given the fact that damage is typically a local phenomenon, the fundamental challenge in the future work is the restriction of the number of test points. Therefore, the experimental procedure must be improved through the combination of experimental methods and mechanical models [1], [2].…”

Section: Discussionmentioning

confidence: 99%

Experimental Identification of a Surface Delamination of a Laminated Sandwich Beam

Proc Appl Math and Mech

Schmieg

2003

The oscillation properties of a laminate structure yields information about its structural integrity.Unilateral constraints and impacts dominate the oscillation properties of delaminated structures. These phenomena give rise to a nonlinear system response, whereas the degree of the nonlinearity augments with increasing intensity of excitation. The distribution of the nonlinearity on various test points allows the localisation of a delamination, exemplarily shown here on a laminated beam with a surface delamination.

“…At each pair of contact nodes the law of impact must be applied and only one parameter is needed, namely the coefficient of restitution, which is known from the preceding experimental investigation. Thus, the numerical procedure is an extension of the ideas for a 2 DOF system [4]. Supplying the harmonic base excitation on the treated system, coupling of both linear subsystems occurs due to impact-like contact events along the beam.…”

Section: Newton's Impact Law For Contact Description Within Fe Methodsmentioning

confidence: 99%

“…The delaminated layer and the remaining part of a sandwich structure periodically strike against one another during the oscillation. This dynamic contact-impact problem has as the simplest approximation two pendulums which are simultaneously excited by harmonic base excitation [4]. Depending on the frequency and amplitude of excitation, a cascade of bifurcations with intermittent windows of irregular motions and different numbers of impacts during one excitation period can occur.…”

Section: Introductionmentioning

confidence: 99%

Clapping in delaminated sandwich-beams due to forced oscillations

2005

Comput Mech

Abstract. Forced oscillations of delaminated composite laminates lead to non-smooth dynamic systems due to continuously developing impact-like contacts along the delamination. The primary aim of this study is to investigate a realistic model situation for delamination problems based on experiments and numerical simulation. First, the properties of lateral impacts on beam-type structures are studied, in particular in regard to the amount of energy dissipation during contact. Taking these results into account the Finite Element method based on beam elements is employed to simulate the stationary state of typical oscillations observed on the delaminated structure paying special attention to the dynamically developing and strongly dissipative contact. To deal with that kind of contact arising between delaminated layers, an effective technique combining a law of impact with the classical penalty method is presented. Confronting numerical results with the experimental reference provides an insight into the accuracy and robustness of the simulation technique.