Dynamics of cracked composite material structures

Abstract

As the result of this work models of the ®nite cracked beam element, delaminated beam element, and also delaminated plate element have been developed. These models have been used for the analysis of the inuence of the fatigue cracks and delaminations on the dynamic characteristics of the constructions made of unidirectional composite materials. The method of modelling cracks and delaminations presented in this work enables its easy modi®cation according to speci®c cases of damage (i.e. oblique crack, two-side crack, inside crack, multiple delaminations etc.).The results obtained from numerical calculations of the presented models are in good agreement with the known in¯uence of damage parameters like: the position and the depth of the crack or the length and the position of the delamination on the natural frequencies. Simultaneously, a strong in¯uence of the material parameters on these changes has been observed, which does not exist in the case of isotropic materials.

Detection of Delamination in Laminate Wind Turbine Blades Using One‐Dimensional Wavelet Analysis of Modal Responses

“…The value of the shear modulus in the case of a damaged laminate was determined by examination of natural vibrations of a simple cantilever beam. The beam natural frequencies were consistent with a reference model, when the shear modulus was lowered to 14% of its initial value [32,42]. This method of delamination modelling is a compromise between the exact representation of damage and the ease of implementation.…”

Hygrothermal effects on the free vibration characteristics of delaminated composite pretwisted rotating conical shells

“…Bandyopadhyay, Karmakar and Kishimoto, Mechanical Engineering Journal, Vol.1, No.6 (2014) 2 2 2 ), a/b=1, a/t=100, for (0/90/90/0) simply-supported graphite-epoxy laminated plates Fig. 3: Effect of the location of delamination on the fundamental frequency of composite cantilever beam (Krawczuk, et. al., 1997) The validation of the computer program in respect of delamination model is furnished in Fig.…”

“…al., 1997) The validation of the computer program in respect of delamination model is furnished in Fig. 3 wherein the present FEM results for the span-wise variation of the first natural frequency of the composite cantilever beam with relative position of delamination along span are compared with those of Krawczuk, et. al.…”

Effect of Location of Delamination on Free Vibration of Cross-Ply Conical Shells

“…On the other hand, Table 3 furnishes the non-dimensional fundamental natural frequencies of isotropic flat rotating cantilever plate [25]. The span-wise variation of fundamental frequency of composite cantilever beam with relative position of delamination [14] is illustrated in Fig. 3.…”

“…Regarding delamination model, two worth mentioning investigations were carried out. It included analytical and experimental determination of natural frequencies of delaminated composite beam by Shen and Grady [13] and the second one dealt with finite element treatment of the delaminated composite cantilever beam and plate by Krawczuk et al [14] for free vibration analyses. Liang et al [23] studied natural vibration of symmetric cross-ply laminated composite conical plate shell by using transfer matrix method, while Narita et al [27] investigated the free vibration characteristics of cross-ply laminated cylindrical shell by leveraging finite element method.…”