Determination of Dewetting Criterion for Nonlinear Solid Propellant Stress Analysis

1975 ◽  
Vol 97 (3) ◽  
pp. 271-277 ◽  
Author(s):  
G. H. Lindsey ◽  
J. E. Woods
Keyword(s):  
Tensile Test ◽  
Stress Analysis ◽  
Data Reduction ◽  
Solid Propellant ◽  
Multiaxial Stress ◽  
Stress Strain ◽  
Strain Behavior ◽  
Idealized Model ◽  
Stress States

A criterion for dewetting in solid propellant materials is developed from an application of Drucker’s postulate to an idealized model of stress-strain behavior. The criterion is evaluated experimentally via dewetting measurements in uniaxial and multiaxial stress states. Development of the method of data reduction for the triaxial tensile test has brought new insight to previous work reported with the test.

Determination of Full Range Stress-Strain Behavior of Pipeline Steels Using Tensile Characteristics

2010 ◽  
Author(s):  
Stijn Hertele´ ◽  
Wim De Waele ◽  
Rudi Denys
Keyword(s):  
Full Range ◽  
Tensile Tests ◽  
Proof Stress ◽  
Stress Strain ◽  
Pipeline Steels ◽  
Strain Behavior ◽  
Parameter Values ◽  
Near Future ◽  
Strain Model

It is standard practice to approximate the post-yield behavior of pipeline steels by means of the Ramberg-Osgood equation. However, the Ramberg-Osgood equation is often unable to accurately describe the stress-strain behavior of contemporary pipeline steels with a high Y/T ratio. This is due to the occurrence of two distinct, independent stages of strain hardening. To address this problem, the authors recently developed a new ‘UGent’ stress-strain model which provides a better description of those steels. This paper elaborates a methodology to estimate suited parameter values for the UGent model, starting from a set of tensile characteristics. Using the proposed methodology, good approximations have been obtained for a preliminary series of eight investigated stress-strain curves. Next to all common tensile characteristics, the 1% proof stress is needed. The authors therefore encourage the future acquisition of this stress level during tensile tests. Currently, the authors perform a further in-depth validation which will be reported in the near future.

scholarly journals Triaxial Failure Behavior of Highly Porous Cementitious Foams Used as Heat Insulation

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1373
Author(s):  
Albrecht Gilka-Bötzow ◽  
Paula Folino ◽  
Andreas Maier ◽  
Eduardus A. B. Koenders ◽  
Antonio Caggiano
Keyword(s):  
Heat Insulation ◽  
Dry Density ◽  
Failure Behavior ◽  
Strength Increase ◽  
Stress Strain ◽  
Thermal Tests ◽  
Strain Behavior ◽  
Stress States ◽  
Air Void ◽  
Highly Porous

This work reports a detailed experimental study that is aimed at investigating the failure mechanisms of highly porous cementitious foams used as heat insulation under triaxial stress states. The designed target dry density of the considered foam mixture was 180 kg/m3 by setting the water-to-cement ratio of the considered cement paste to 0.4. The mechanical experiments were accompanied by thermal tests to observe the effect that specific air void structures have on the resulting insulation properties and by micro-to-meso geometric studies to identify and classify the inner structure of the considered mineralized foams. Unconfined compressive strengths were performed first, obtaining peak stresses of 0.252, 0.283, 0.223, and 0.251 (results in MPa), corresponding to peak strains of 39.0, 28.6, 45.3, and 20.6 (in ×10−3 mm/mm), respectively. Moreover, three triaxial confinement levels of 33%, 66%, and 90% of the mean uniaxial compressive strength (fc) were adopted. The results showed that a 33% confinement may cause a strength increase and an almost perfect elastic–plastic stress–strain behavior. However, higher levels of confinements (i.e., 66% and 90%) produced very unstable behaviors in terms of the final strength and stress–strain response.

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