Multiphysics Based Simulation of Damage Progression in Composites

Abstract

The long-term properties of continuous fiber reinforced composite materials are increasingly important as applications in airplanes, cars, and other safety critical structures are growing rapidly. Although a clear understanding has been established for initiation, growth and accumulation of damage, it is still unclear when and how the interactions of these local events lead to the development of a "critical" fracture path resulting in a sudden change of global properties and possible rupture. In the present paper, we simulate damage development in a neat polymeric resin using X-FEM analysis, and conduct concomitant dielectric response analysis with a COMSOL TM simulation model to study the collective defect structure as it develops in a model system. Our studies reveal inflection points in the predicted global dielectric response vs. strain that are related to changes in local damage growth rates and modes that clearly indicate impending fracture and capture the progressive change in material state.

Interfacial nanocomposite sensors (sQRS) for the core monitoring of polymer composites’ fatigue and damage analysis

“…Wang et al [49] have explained the three stages of damage evolution in carbon fiber-reinforced cement (CFRC) with cyclic fatigue as follows: (1) damage nucleation followed by (2) damage expansion and finally (3) an unstable damage development. Damage mechanisms in cross-ply composite laminates have been studied for decades and are also following the same kind of sequence from crack initiation, transverse crack in the plies normal to the applied loading direction, delamination at the interface of plies to fiber breakage at ultimate fracture as pointed out by Vadlamudi et al [50] Quaresimin et al [51] and Dzenis [52] . The same stages of damage growth are evidenced in Figure 9, as both curves of relative load loss F max / F 0max and sQRS piezo-resistive response A r versus the logarithm of the number of cycles, reveal the presence of three, or more steps during the damage growth.…”

Global Prediction of Discrete Local Damage Interactions Using Broadband Dielectric Spectroscopy

“…as a function of frequency with high precision. In the current work, a frequency of 10 Hz was used for the dielectric response in order to obtain low frequency response with a high sampling rate which is crucial to capture the change in material state [7,14]. The insitu setup is shown below in figure 3.…”

“…Vadlamudi et al, developed a multiphysics model that captures the change in material state by performing a conformal dielectric study on the predicted cracks. They applied it successfully for an isotropic material and 1 ply CFRP lamina [14]. The equations that govern the dielectric response are given below:…”

Study of Defect Coalescence in Heterogeneous Material Systems Using Broad Band Dielectric Spectroscopy

“…Uniaxial displacement was applied in the X direction and a 1Volt AC signal was applied perpendicular to the loading direction through the thickness, as shown in figure 5. The homogeneous material system meant that there would be no damage progression implying once the damage initiates it would immediately fail [4]. The hole in the coupon acted as the stress concentrator.…”

“…Consider, the impedance at the initial undeformed state as Z0, the normalized impedance will be calculated as norm Z = Z Z0 (4) For the initial undeformed state norm Z will be 1; the variation in normalized impedance at various excitation frequencies for different a/w ratios is shown in figure 8(b). It was observed that only at low frequencies in the range 1 mHz to 10 Hz the change in material state was captured, and at higher frequencies the response is similar at all frequencies.…”