Material Strength and Inelastic Deformation Mechanisms in Shocked Ceramics

2000 ◽  
Author(s):  
Yogendra M. Gupta
Keyword(s):  
Inelastic Deformation ◽  
Deformation Mechanisms ◽  
Material Strength

Scanning Electron Microscopic Analysis on the Deformation Mechanisms in NACRE

2001 ◽  
Vol 7 (S2) ◽  
pp. 1118-1119
Author(s):  
R.Z. Wang ◽  
Z. Suo ◽  
A.G. Evans ◽  
N. Yao ◽  
I.A. Aksay
Keyword(s):  
Inelastic Deformation ◽  
Microscopic Analysis ◽  
Deformation Mechanisms ◽  
Biological Macromolecules ◽  
Electron Microscopic ◽  
Princeton University ◽  
Structural Details ◽  
Tension And Compression ◽  
Stereo Microscope ◽  
Scanning Electron

Princeton Materials Institute, Princeton University, Princeton, New Jersey 08544 Some biological materials exhibit structural robustness, despite the brittle nature of their constituents.Nacre (mother-of-pearl), the pearly internal layer of many mollusc shells, is addressed in this study. This material comprises about 95% aragonite tablets (a mineral form of CaC03), The polygonal tablets were glued with only a few percent of biological macromolecules into layered structure. The goal of the present study is to elucidate the basic inelastic deformation mechanisms.Typical stress /strain curves in tension and compression are plotted in Fig. 1. All tensile curves exhibited extensive inelastic deformation. After testing, the samples were initially examined using a stereo microscope (Leica MZ8) and a metallurgical microscope (Leica MEF4M) followed by analysis of the structural details using scanning electron microscopy (Philip XL-30). Optical imaging provided a visualization of the inelastic zone, manifest as white tension lines.

Deformation mechanisms in nacre

2001 ◽  
Vol 16 (9) ◽  
pp. 2485-2493 ◽  
Author(s):  
R. Z. Wang ◽  
Z. Suo ◽  
A. G. Evans ◽  
N. Yao ◽  
I. A. Aksay
Keyword(s):  
Steady State ◽  
Inelastic Deformation ◽  
Inelastic Strain ◽  
Shear Resistance ◽  
Deformation Mechanisms ◽  
Interfacial Sliding ◽  
Underlying Mechanisms ◽  
Loading Axis ◽  
State Stress ◽  
Mollusc Shells

Nacre (mother-of-pearl) from mollusc shells is a biologically formed lamellar ceramic. The inelastic deformation of this material has been experimentally examined, with a focus on understanding the underlying mechanisms. Slip along the lamellae tablet interface has been ascertained by testing in compression with the boundaries oriented at 45° to the loading axis. The steady-state shear resistance τss has been determined and inelastic strain shown to be as high as 8%. The inelastic deformation was realized by massive interlamellae shearing. Testing in tension parallel to the tablets indicates inelastic strain of about 1%, occurring at a steady-state stress, σsss ≈ 110 MPa. The strain was associated with the formation of multiple dilatation bands at the intertablet boundaries accompanied by interlamellae sliding. Nano-asperities on the aragonite tablets and their interposing topology provide the resistance to interfacial sliding and establish the level of the stress needed to attain the inelastic strain. Detailed mechanisms and their significance for the design of robust ceramics are discussed.

Sign in / Sign up

Export Citation Format

Share Document