Location

La Jolla, CA

Start Date

1-1-1991 12:00 AM

Description

Many ceramic matrix composites have been investigated to enhance fracture toughness of ceramics. Especially in continuous fiber reinforced ceramics remarkable increase of toughness has been reported [1,2]. In such composites, it is very important that the mechanism of stress shielding can enhance fracture toughness, in which crack bridging and sliding of interface between matrix and fiber occur and then stress is transferred. The SiC fiber reinforced glass composite was used as a model material where friction between matrix and fiber provides stress transfer. The interfacial shear stress of this composite has been measured by the indentation method [3,4]. AE waveforms during this test were recorded. In this paper we try to identify the microfracture mechanisms by using AE radiation pattern which is a far-field displacement of AE waveform [5,6]. Quantitative parameters of microcracking such as size and mode in monolithic materials have been evaluated by using the advanced AE measuring system with 6 channels and analysis system [7]. However, there are many types of microfracture in these composites and mechanical model of each microfracture for AE is not clear. Here we try to classify microfractures into several types. And then fracture process of this composite will be discussed.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

10B

Chapter

Chapter 6: Engineered Materials

Section

Defects in Composites

Pages

1499-1506

DOI

10.1007/978-1-4615-3742-7_47

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Acoustic Emission Waveform Analysis in Composites

La Jolla, CA

Many ceramic matrix composites have been investigated to enhance fracture toughness of ceramics. Especially in continuous fiber reinforced ceramics remarkable increase of toughness has been reported [1,2]. In such composites, it is very important that the mechanism of stress shielding can enhance fracture toughness, in which crack bridging and sliding of interface between matrix and fiber occur and then stress is transferred. The SiC fiber reinforced glass composite was used as a model material where friction between matrix and fiber provides stress transfer. The interfacial shear stress of this composite has been measured by the indentation method [3,4]. AE waveforms during this test were recorded. In this paper we try to identify the microfracture mechanisms by using AE radiation pattern which is a far-field displacement of AE waveform [5,6]. Quantitative parameters of microcracking such as size and mode in monolithic materials have been evaluated by using the advanced AE measuring system with 6 channels and analysis system [7]. However, there are many types of microfracture in these composites and mechanical model of each microfracture for AE is not clear. Here we try to classify microfractures into several types. And then fracture process of this composite will be discussed.