Abstract
This paper investigates the elastic behavior of bilaminate-composite coupons segmented from a filament-wound rocket case and of a laboratory prepared flat panel for direct tension-compression and flexural loading under static and dynamic conditions. New methods of testing have been developed which are primarily applicable to composite constructions. The dynamic test consists of exciting the primary free-free resonant mode of a specimen. Flexure tests utilizing a unique pure-bend system are employed for the static evaluations. The composite moduli determined from the static and dynamic test are compared with analytic values. The analytic values for the composite are derived from tension-compression and flexure analytical models using the material properties of the constituents. The measured elastic moduli compared favorably with analytical prediction and are indicative of the history of loading effects as well as the crazed condition of the composite constructions. The moduli determined by the dynamic test showed the closest agreement with analytic values, with a difference of 0 to 16 percent.
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Abbreviations
- a :
-
distance betweenx 1 andx 2
- A i :
-
area of lamina section
- b :
-
width of specimen
- d :
-
depth of neutral axis
- dA :
-
increment of area
- E a :
-
assumed modulus of metallic member
- E C :
-
compression modulus
- E L :
-
modulus of lamina one, longitudinal
- E T :
-
tension modulus
- E TC :
-
average tension-compression modulus
- E TR :
-
modulus of lamina two, transverse
- e :
-
ratio of the moduli of a bilaminate
- f :
-
frequency
- GL :
-
gage length, distance between grips
- g :
-
acceleration of gravity
- h :
-
beam depth
- I :
-
moment of inertia
- l :
-
length of specimen
- M :
-
bending moment
- m :
-
variable in eqs (8) and (9)
- n :
-
mode constant
- P L :
-
percent of section, lamina one
- P T :
-
percent of section, lamina two
- t :
-
thickness of composite
- y :
-
distance from neutral axis todA
- y i :
-
centroidal distance
- x 1,x 2 :
-
output displacement transducers
- σ:
-
stress
- θ:
-
angle of bend
References
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Moscow Technical University, “Effect of Shear on the Modulus of Elasticity of Specimens of Glass-fiber Reinforced Plastics Tested in Transverse Bending,” IAA-465-15598 (June 1964).
“Symposium on Determination of Elastic Constants,” American Society for Testing Materials, Special Technical Publication No. 129 (June 25, 1952).
Hill, R. G., “Evaluation of Engineering Material by Pure Bend Test,” Thesis, University of Washington (March 1, 1960).
Aerojet-General Corp., “Dynamic Filament Wound Reinforced Plastics Materials Test Program,” Aerojet Tech. Rept. (July 1964).
“Behavior of Materials Under Dynamic Loading,” Papers Presented at a Colloquium at the Winter Annual Meeting, ASME, Chicago, Ill. (Nov. 9, 1965).
Aerojet-General Corp., “Composite Properties of Filament-Resin Systems,” L. R. Hermann and K. S. Pister, Aerojet Tech. Rept. No. 119SRP (August 1962).
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Hill, R.G. Evaluation of elastic moduli of bilaminate filament-wound composites. Experimental Mechanics 8, 75–81 (1968). https://doi.org/10.1007/BF02326130
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DOI: https://doi.org/10.1007/BF02326130