Large deformation dynamic bending of composite beams
Abstract
The large deformation response of composite beams subjected to a
dynamic axial load was studied. The beams were loaded with a moderate
amount of eccentricity to promote bending. The study was primarily
experimental but some finite element results were obtained. Both the
deformation and the failure of the beams were of interest. The static
response of the beams was also studied in order to determine the
difference between the static and dynamic failure. Twelve different
laminate types were tested. The beams tested were 23 in. by 2 in. and
generally 30 plies thick. The beams were loaded dynamically with a
gravity-driven impactor traveling at 19.6 ft./sec. and quasi-static
tests were done on identical beams in a displacement controlled
manner. For laminates of practical interest, the failure modes under
static and dynamic loadings were identical. Failure in most of the
laminate types occurred in a single event involving 40% to 50% of the
plies. However, failure in laminates with 30° or 15° off axis plies occurred in several events. All laminates exhibited bimodular
properties. The compressive flexural moduli in some laminates was
measured to be 1/2 the tensile flexural modulus. No simple relationship
could be found among the measured ultimate failure strains of the
different laminate types. Using empirically determined flexural
properties, a finite element analysis was reasonably accurate in
predicting the static and dynamic deformation response.
Collections
- Masters Theses [19612]