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Composite sandwich structures offer several advantages
over conventional structural materials such as lightweight, high
bending and torsional stiffness, superior thermal insulation and
excellent acoustic damping. One failure mechanism in a composite
sandwich structure is the debonding of the composite facesheets from the
core structure. A well-formed adhesive fillet at the interface of the
honeycomb core cell walls and the laminate is a significant factor in
preventing bond failure. In the present work, honeycomb composite
sandwich panels are manufactured using a low-cost
vacuum-bag-pressure-only out-of-autoclave manufacturing process.
CYCOM®5320 out-of autoclave prepreg is used for the facesheet laminates

Preimpregnated fibers or prepregs are widely used to
produce high quality composite parts. One process in particular, known
as cavity molding, is frequently used to process high quality thick
composite details with exceptionally precise dimensions by using a
platen press to apply heat and pressure to rigid tooling and thereby
entice the prepreg within to cure into the shape of the confines of an
internal cavity. The objective of the research described here is to
develop an mathematical model for glass/epoxy prepreg which simulates
the resin flow, heat transfer, consolidation and curing of cavity-molded
flex beams which varies significantly with location. An enhanced
understanding of the mechanisms involved will help significantly improve

Continuous fiber reinforced ceramic composites (CFCCs) are widely used
in high performance and high temperature applications. The behavior of
CFCCs under various conditions is not easily predicted. Micromechanical
modeling of the CFCCs using a representative volume element (RVE)
approach provides useful prediction of the composite behavior.
Conventionally, the effect of the fiber-matrix interface on the
effective property prediction of the CFCCs is not considered in the
micromechanical modeling approach. In the current work, a comprehensive
three-dimensional micromechanical modeling procedure is proposed for
effective elastic behavior estimation of CFCCs. Application of the
micromechanical model for various interfaces has been considered to

Large scale, intricate shape parts with widely varying
cross-sections find difficulty in manufacturing using conventional
manufacturing processes. Cavity molding, a process similar to
compression molding is unique and often used in rotorcraft industries to
manufacture thick flex beam composite parts with high viscosity resins.
The curing of thermosetting resins used in these applications is
usually accompanied by an exothermic reaction and excessive heat buildup
during the polymerization reaction can cause internal stresses to
build-up and result in structural defects in thick composite structures.
Process optimization of flex beam composite parts manufactured using
the cavity molding process will result higher quality parts. In this

2014 W. M. KECK INSTITUTE FOR SPACE STUDIES POSTDOCTORAL FELLOWSHIP CALL RELEASED

Application Deadline: NOON PST 02 December 2013 

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Recently, I am reading several classic works on crystal plasticity. But, it seems to be difficult for me to obtain several very old papers in this area. For example, one of the classic papers on Hall-Petch relation,

Petch, N.J., The cleavage strength of polycrystals. The Iron and Steel Institute, 1953, 174: 25-28. I have tried many ways to get the original paper, but I finally failed. Could someone please send me a copy of this paper? Thanks a lot. Here is my email: dbliu2009 [at] gmail.com