Badania ultradźwiękowe płyt włóknisto-cementowych

Abstract

StreszczenieW artykule przedstawiona została możliwość lokalizacji delaminacji w płycie włóknisto-cementowej za pomocą specjalnie do tego celu skonstruowanego urządzenia wykorzystującego metodę ultradźwiękową i fale podłużne. Przeprowadzono badania na trzech rodzajach płyt. Stwierdzono, że proponowana metoda diagnostyczna umożliwia wykrywanie lokalnych nieciągłości, np. obszarów o obniżonej zwartości, czy delaminacji w płytach włóknisto-cementowych na obszarze średnicy wiązki metodą estymacji prędkości fali ultradźwiękowej. Zaletami metody są niewielkie wymiary urządzenia i krótki czas badania. AbstractThis article presents the possibility of delamination location in the fiber-cement board using a specially-designed device operating on the principle of ultrasonic method and measuring of longitudinal waves velocity. Studies were carried out on three types of board. It was found that the proposed diagnostic method allows detection of local discontinuities, eg. the areas of reduced compactness, or delamination in fiber-cement boards in the area of the beam diameter by an estimation velocity of ultrasonic waves. The advantages of the method are: small dimensions of the device and short duration of the study.

Effect of Freeze–Thaw Cycling on the Failure of Fibre-Cement Boards, Assessed Using Acoustic Emission Method and Artificial Neural Network

“…A method of detecting delaminations in composite elements by means of an ultrasonic probe was presented in a study by Stark, Vistap et al [21]. Ultrasonic devices and a method used to detect delaminations in fibre-cement boards were described by Dębowski et al [7]. Berkowski et al [22], Hoła and Schabowicz [23] and Davis et al [24] proposed the use of the impact-echo method jointly with the impulse response method to recognize delaminations in concrete elements.…”

“…It is worth noting that research on fibre-cement boards has so far been mostly limited to determining—solely through the bending strength (modulus of rupture, MOR ) test—their standard physicomechanical parameters and the effect of in-service factors (e.g., soaking–drying cycles, heating–raining cycles and high temperatures) and the various fibres and production processes [6]. Only a few cases of testing fibre-cement boards by non-destructive methods, limited to imperfections arising during the production process, can be found in the literature [7,8,9,10]. Besides the effects of high temperature and fire described in [11,12], the impact of sub-zero temperatures is one of the most destructive in-service factors to many building products, particularly composite products containing reinforcement in the form of various fibres, especially fibres of organic origin (to which cellulose fibres belong).…”

Identification of the Degree of Degradation of Fibre-Cement Boards Exposed to Fire by Means of the Acoustic Emission Method and Artificial Neural Networks

“…Paper [18] by Stark describes a method of detecting delaminations in composite elements by means of a moving ultrasonic probe. An ultrasonic device and a way of detecting delaminations are described in work [7] by Dębowski, Lewandowski, Mackiewicz, Ranachowski and Schabowicz. In works by Berkowski et al [19], Hoła and Schabowicz [20] and Davis et al [21] it was proposed to use the impact-echo method jointly with the impulse response method to identify delaminations in concrete members.…”

“…Most of the research on fibre-cement boards to date has been limited to determining their standard physicomechanical properties, the effect of operational factors, such as soak–dry cycles, freeze–thaw cycles, heating, raining and high temperatures, and the effect of the use of various types of fibres and production processes, solely through bending ( MOR ) tests [6]. In the literature on the subject, one can find only a few nondestructive tests carried out on fibre-cement boards, limited to the imperfections arising during production [7,8,9,10]. The effect of fire is one of the most destructive accidental factors for many building products, especially the composite ones containing reinforcement in the form of fibres of various kinds, particularly cellulose fibres, considering that at a temperature above 200 °C cellulose fibres undergo pyrolysis.…”