Noha M. Hassan

A Heat Transfer Analysis of the Fiber Placement Composite Manufacturing Process

A computer code is developed to accurately simulate the three-dimensional heat transfer during the thermoset fiber placement composite manufacturing process. The code is based on the Lagrangian formulation of the problem. Eight-node brick elements are employed, and the 2 × 2 × 2 integration rule is used to numerically evaluate the integrals over an element. The coupled ordinary differential equations obtained by the semidiscrete formulation of the problem are integrated by the unconditionally stable backward difference method. The code is validated by comparing the computed results for several problems with those available in the literature. Composite rings are manufactured by continuously laying a tape over a cylindrical mandrel and the temperature histories at several points are measured with thermocouples. The computed temperature distribution is found to compare well with the test findings. The code can be used to optimize the processing variables.

Discrete event simulation: a vital tool for a concurrent life cycle design

Purpose – The purpose of this study is to examine whether discrete event simulation (DES) can be equally utilised in the design phase of the architecture, engineering and construction industry (AEC) projects to achieve a more efficient facility layout. Facility design is a complex process involving diverse disciplines, tasks, tools and events. Integrating key participants involved in the design generally leads to a more satisfied end-user. The AEC thoroughly examined different approaches to enhance this integration through improved communication, visualisation and coordination among the different project participants. DES has been used extensively as a tool for analysis and evaluation, especially during the construction process. Design/methodology/approach – A facility planning framework is illustrated that combines both qualitative and quantitative analysis to achieve a performance-driven design. An investigative qualitative research approach is used to determine the design criteria and performance metri...

Modeling of Progressive Damage in High Strain-Rate Deformations of Fiber-Reinforced Composites

We use the theory of internal variables, or equivalently of continuum damage mechanics, to develop a mathematical model involving three variables to describe the evolution of progressive damage in high strain—rate deformations of fiber-reinforced composites. The degradation of material parameters with the damage is considered. Values of material parameters in the postulated evolution laws of internal variables are determined from the test data. The delamination mode of failure is simulated by hypothesizing a damage surface in terms of transverse normal and transverse shear stresses acting on an interface between two adjoining layers. When the stress state at a point on an interface lies on this surface, delamination is assumed to ensue from that point. Initial-boundary-value problems are numerically solved to validate the mathematical model by comparing computed results with test findings. A Figure of Merit, equal to the percentage of work done by external forces dissipated by all failure mechanisms, is introduced to characterize the performance of laminated composites under shock loads.