Home  About us  Contact
 

Thermal Signature (thermal + signature)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Evaluation of Damage Evolution in Ceramic-Matrix Composites Using Thermoelastic Stress Analysis

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2000
Thomas J. Mackin
Thermoelastic stress analysis (TSA) has been used to monitor damage evolution in several composite systems. The method is used to measure full-field hydrostatic stress maps across the entire visible surface of a sample, to quantify the stress redistribution that is caused by damage and to image the existing damage state in composites. Stress maps and damage images are constructed by measuring the thermoelastic and dissipational thermal signatures during cyclic loading. To explore the general utility of the method, test samples of several ceramic-matrix and cement-matrix composites have been fabricated and tested according to a prescribed damage schedule. The model materials have been chosen to illustrate the effect of each of three damage mechanisms: a single crack that is bridged by fibers, multiple matrix cracking, and shear bands. It is shown that the TSA method can be used to quantify the effect of damage and identify the operative damage mechanism. Each mechanism is identified by a characteristic thermal signature, and each is shown to be effective at redistributing stress and diffusing stress concentrations. The proposed experimental method presents a new way to measure the current damage state of a composite material. [source]

Detecting sub-surface cracking in laminated membranes using infrared imaging

POLYMER COMPOSITES, Issue 6 2001
Thomas J. Mackin
This paper presents a new experimental method that utilizes the thermoelastic effect to detect sub-surface cracks in a laminated polymer membrane. A highly accurate infrared camera is used to measure the thermoelastic and dissipational heat signatures associated with bi-axial fatigue loading of membranes. Changes in these thermal signatures arise whenever cracks form in any layer of the laminate, including fully embedded layers, thereby providing a novel method for experimentally measuring the initiation and growth of damage in sub-surface layers. The proposed method is illustrated using a model 3-layer system of EVOH sandwiched between two polyurethane layers. Bi-axial fatigue loading was used to initiate cracking in the central EVOH layer without damaging the outer polyurethane layers. Cracking in the central layer resulted in a distinct thermal signature that was plainly visible using the proposed method. [source]

Evaluation of Damage Evolution in Ceramic-Matrix Composites Using Thermoelastic Stress Analysis

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2000
Thomas J. Mackin
Thermoelastic stress analysis (TSA) has been used to monitor damage evolution in several composite systems. The method is used to measure full-field hydrostatic stress maps across the entire visible surface of a sample, to quantify the stress redistribution that is caused by damage and to image the existing damage state in composites. Stress maps and damage images are constructed by measuring the thermoelastic and dissipational thermal signatures during cyclic loading. To explore the general utility of the method, test samples of several ceramic-matrix and cement-matrix composites have been fabricated and tested according to a prescribed damage schedule. The model materials have been chosen to illustrate the effect of each of three damage mechanisms: a single crack that is bridged by fibers, multiple matrix cracking, and shear bands. It is shown that the TSA method can be used to quantify the effect of damage and identify the operative damage mechanism. Each mechanism is identified by a characteristic thermal signature, and each is shown to be effective at redistributing stress and diffusing stress concentrations. The proposed experimental method presents a new way to measure the current damage state of a composite material. [source]

Detecting sub-surface cracking in laminated membranes using infrared imaging

POLYMER COMPOSITES, Issue 6 2001
Thomas J. Mackin
This paper presents a new experimental method that utilizes the thermoelastic effect to detect sub-surface cracks in a laminated polymer membrane. A highly accurate infrared camera is used to measure the thermoelastic and dissipational heat signatures associated with bi-axial fatigue loading of membranes. Changes in these thermal signatures arise whenever cracks form in any layer of the laminate, including fully embedded layers, thereby providing a novel method for experimentally measuring the initiation and growth of damage in sub-surface layers. The proposed method is illustrated using a model 3-layer system of EVOH sandwiched between two polyurethane layers. Bi-axial fatigue loading was used to initiate cracking in the central EVOH layer without damaging the outer polyurethane layers. Cracking in the central layer resulted in a distinct thermal signature that was plainly visible using the proposed method. [source]