(tkks) akibat beban tekan statik dan impak (simulasi numerik)

ABSTRACT
Experimental and numerical work was reported on the problem of the
response of oil palm empty fruit bunch (OPEFB) fiber reinforced polymeric foam
under static and impact loading conditions. In the experimental investigation, the
static axial compressive test was applied on polyurethane, thermosetting resins, and
OPEFB fiber reinforced polymeric foam specimens and these specimens were
conducted on a servohydraulic material testing machine. The averaged stress-strain
response and the fracture modes in each type of materials were derived from static
test. The fracture modes in each type of materials and the collapsed cells of OPEFB
fiber reinforced polymeric foam were observed by a scanning electron microscope. In
the numerical simulation, the variation of the distributions of normal stresses with
normalized time in OPEFB fiber reinforced polymeric foam due to static and impact
wave propagation was analyzed by using a finite element method (FEM). The finite
element code ANSYS and NASTRAN were used for numerical stress analysis. The
obtained summaries were as followed: (1) The yield stress, the maximum stress, and
the strain to failure were influenced by foams, these foams reduced the stress and
decreased the strain to failure. The fracture modes were also found to be
considerably different for each type of materials. Polyurethane exhibited random
macroscopic fracture, thermosetting resins and OPEFB fiber reinforced polymeric
foam exhibited shear dominated failure and the cells suffered progressive crushing.
(2) Based on FEM computation results were found that the fracture mechanism
corresponded to the regions of the static compressive stress concentration. (3) FEM
computation results suggested that the propagation of incident compressive stress
wave related to impact loading. (4) Based on the static axial compressive test results,
the Young’s modulus and the stiffness were determined and it was found that
thermosetting resins may also contributed to increased the stiffness of polyurethane.
Keywords: polymeric foam, OPEFB fiber, static compressive stress, incident
compressive stress, Young’s modulus, stiffness
Universitas Sumatera Utara