An experimental/analytical study of strains in encapsulated assemblies
A combined experimental and analytical study of strains that develop in encapsulated assemblies during casting, curing and thermal excursions is described. The experimental setup, designed to measure in situ strains, consisted of thin, closed-end, metal tubes that were instrumented with strain gages and thermocouples before being over-potted with an encapsulant. Three epoxy-based materials were studied. After cure of the encapsulant, tube strains were measured over the temperature range of {minus}55{degrees}C to 90{degrees}C. The thermal excursion experiments were then numerically modeled using finite element analyses and the results were compared to the experimental results. The predicted strains are overestimated (conservative) when a linear, elastic, temperature-dependent material model was assumed for the encapsulant and the stress free temperature was assumed to correspond to the cure temperature of the encapsulant. Very good agreement was obtained with the linear elastic calculations provided that the stress free temperature correspond to the onset of the glassy-to-rubbery transition range of the encapsulant. Finally, very good agreement was obtained when a viscoelastic material model was utilized and a stress free temperature corresponding to the cure temperature was assumed. 8 refs., 12 figs., 3 tabs.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5913928
- Report Number(s):
- SAND-91-1748C; CONF-920452--1; ON: DE92003576
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360603* -- Materials-- Properties
42 ENGINEERING
426000 -- Engineering-- Components
Electron Devices & Circuits-- (1990-)
ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COBALT ALLOYS
ELASTICITY
ELECTRONIC EQUIPMENT
ENCAPSULATION
EPOXIDES
EQUIPMENT
FINITE ELEMENT METHOD
IRON ALLOYS
IRON BASE ALLOYS
KOVAR
MANGANESE ADDITIONS
MANGANESE ALLOYS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
NICKEL ALLOYS
NUMERICAL SOLUTION
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
POLYMERS
STRAINS
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TENSILE PROPERTIES
TUBES