Evolution of damage-induced nonlinearity in proximity of discontinuities in concrete

Abstract

a b s t r a c tUnderstanding the mechanisms and modalities of damage progression close to discontinuities in solids, such as joints, is of great importance for applications in different fields. The interaction between damage and elasticity causes a nonlinear elastic response of the sample to a stress excitation (e.g. in the ultrasonic frequency range). Extracting physical or mechanical information on the sample properties from recorded ultrasonic signals requires a realistic model and an efficient detection method, as it will be discussed in this paper. We study here the successive phases that concrete samples with discontinuities enter by progressively increase the applied external load. Considerations on the mechanisms of damage progression are derived from experimental data using a Preisach-Mayergoyz space approach, developed in order to capture all the observed behaviors.

Nonlinear elastic response of thermally damaged consolidated granular media

“…The increase in the exponent value is quite regular, and it is known to be an indication of microstructural changes due to the appearance of different nonlinear features, such as cracks/joints behaving as clapping interfaces during the passage of large strain elastic waves. 38,39 Figures 6(a) and 6(c) show that both the TOF and the power law exponent are positively correlated with the loading temperature. Figure 6(d) shows that the two variables are also well correlated with each other.…”

Ultrasonic Monitoring of the Interaction between Cement Matrix and Alkaline Silicate Solution in Self-Healing Systems

“…It was conducted in accordance with the Scaling Subtraction Method (SSM) procedure and therefore allowed taking into account the contributions to nonlinearity due not only to higher order harmonics generation (see Section 3.2), but also to the nonlinear attenuation and phase shift phenomena, as pointed out in [43]. As fully detailed in previous works [30,44,45,53], the SSM protocol consisted of:exciting the specimens using a sequence of pulses at various amplitudes $A_i$ in the range 50 mV–15 V (by means of the same equipment described in Section 2.3). More specifically, a rectangular pulse of width $t=10\mathrm{sans-serif\mu }$s was used;…”

Influence of noise on the threshold for detection of elastic nonlinearity

“…Note that early damage starts at a load of 4 MPa, while rupture occurs at about 15 MPa, as shown elsewhere. 27 Both y SSM and y FFT depend on x u as a power law with exponent 1. For what concerns the analysis in the time domain ( Fig.…”