Understanding mechanical failure of graphite rocket nozzle throats under thermal stresses

2021 ◽  
pp. 107152
Author(s):  
Barış Nigar ◽  
Serhan Dönmez ◽  
Demirkan Çöker ◽  
Sezer Özerinç
1990 ◽  
Vol 112 (1) ◽  
pp. 35-40 ◽  
Author(s):  
G. C. Scott ◽  
G. Astfalk

Thermal stress cracking is a significant mechanical failure mode in microelectronic components. This failure results from elevated stresses in components exposed to elevated temperatures due to the mismatch of thermal and mechanical properties of the constituent materials. The underlying mechanism responsible for these elevated stresses is not well understood. Therefore, we developed general mathematical and computational techniques for modeling the evolution of these stresses. As a test vehicle, we applied these techniques to thermal stress evolution in multilayer ceramic capacitors (MLCC). Thermal stress cracking has been implicated in significant, industry-wide problems associated with the cracking of these components. The model is used to solve for the transient development of thermal and mechanical gradients across the two spatial dimensions of the MLCC mid-plane. Material types with different thermal and mechanical properties and the interfaces between the material types are specifically included in the model. The stress field solutions are used to indicate when and where mechanical failure is expected to occur. The solutions of the model equations have been obtained using special partial differential equation solvers implemented on a CONVEX C120/220 supercomputer. The model is used to investigate the effects of MLCC termination geometry and material properties on the evolution of thermal stresses.


2018 ◽  
Vol 202 ◽  
pp. 01006
Author(s):  
D. Sujan ◽  
L. Vincent ◽  
Y. W. Pok

The study of thermal mismatch induced stresses and their role in mechanical failure is one relevant topic to composite materials, photonic devices and electronic packages. Therefore, an understanding of the nature of the interfacial stresses under different temperature conditions is necessary in order to minimize or eliminate the risk of mechanical failure. An accurate estimate of thermal stresses in the interfaces plays a significant role in the design and reliability studies of microelectronic devices. In the microelectronic industry, from a practical point of view, there is a need for simple and powerful analytical models to determine interfacial stresses in layered structures. This review paper summarizes the work conducted by the authors in relation to the bi-layered assembly with different temperature conditions on the determination of interfacial thermal stresses. The authors have extended the case of uniform temperature model by earlier researchers of two layered structure to account for differential uniform temperatures, linear temperature gradient in the layers. The presence of a heat source in one layer (die) is also presented. Finally, the effect of bond material properties and geometry on interfacial stresses and bond material selection approach are also considered in a simple way.


Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.


1999 ◽  
Vol 30 (4-6) ◽  
pp. 296-302
Author(s):  
F. V. Nedopekin ◽  
Victor K. Tolstykh ◽  
N. A. Volodin ◽  
V. V. Belousov ◽  
S. V. Gridin

AIAA Journal ◽  
2002 ◽  
Vol 40 ◽  
pp. 1228-1232 ◽  
Author(s):  
B. V. Sankar ◽  
J. T. Tzeng

Sign in / Sign up

Export Citation Format

Share Document