prathyush963's blog

Comparing experimental fracture properties and micromechanical (or global-local/multiscale) finite element simulations

I am interested in developing a global-local finite element model (micro/macro) to simulate flexural testing of a composite material. Flexural loading will be applied on global model (macro) and crack propagation will be simulated in the local model (micro). I want to compare stress intensity factor or any other fracture property obtained from local model (micro) with that of experimental results.

I would appreciate if anyone could suggest some references/literature in this area. Any kind of suggestions would be great!


Evaluation of Skin-core Adhesion Bond of Out-of-autoclave Honeycomb Sandwich Structures

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

Cure and Consolidation Study of Cavity Molded Flex Beam Composite Parts

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

Three-dimensional Micromechanical Modeling of Continuous Fiber Reinforced Ceramic Composites with Interfaces

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

Modeling and Simulation of Moisture Diffusion in Hybrid Fiber-reinforced Polymer Composites

Hybrid fiber-reinforced polymer composites have
extensive applications due to their high strength, corrosion resistance,
low maintenance and design flexibility. However, moisture absorbed by
composite components plays a detrimental role in the integrity and
durability of hybrid structure since it can degrade the mechanical
properties and induce interfacial delamination failures. In the current
study, the moisture diffusion characteristics in two-phase
(unidirectional S-glass fiber reinforced epoxy matrix/unidirectional
graphite fiber reinforced epoxy matrix) hybrid composites using moisture
concentration-dependent diffusion method have been investigated. In the
moisture concentration-dependent diffusion method, the diffusion

Process Optimization of Composite Flex Beams using Neural Networks

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

Random strength (weibull distribution) input at each integration point in Abaqus


 I am trying to input random strength (following weibull distribution) at each integration point. I want to use either USDFLD (preferably) or UMAT subroutines in Abaqus. Please help me in this regards. Any references/suggestions will be great.


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