An Enriched Shell Element for Delamination Simulation in Composite Laminates

A formulation is presented for an enriched shell finite element capable of delamination simulation in composite laminates. The element uses an adaptive splitting approach for damage characterization that allows for straightforward low-fidelity model creation and a numerically efficient solution. The Floating Node Method is used in conjunction with the Virtual Crack Closure Technique to predict delamination growth and represent it discretely at an arbitrary ply interface. The enriched element is verified for Mode I delamination simulation using numerical benchmark data. After determining important mesh configuration guidelines for the vicinity of the delamination front in the model, a good correlation was found between the enriched shell element model results and the benchmark data set

AF-Shell 1.0 User Guide

This document serves as a user guide for the AF-Shell 1.0 software, an efficient tool for progressive damage simulation in composite laminates. This guide contains minimal technical material and is meant solely as a guide for a new user to apply AF-Shell 1.0 to laminate damage simulation problems

Simulation Tool for Damage in Composite Laminates

A numerical simulation tool for progressive failure in laminates utilizes a low fidelity approach. The numerical model includes an enriched element that is initially in a low fidelity form. The enriched elements may increase fidelity by splitting locally to simulate an ongoing damage process such as delamination

Interaction of Delaminations and Matrix Cracks in a CFRP Plate, Part II: Simulation Using an Enriched Shell Finite Element Model

Numerical simulations are presented of a recently developed test which creates multiple delaminations in a CFRP laminate specimen that grow and interact via transverse matrix cracks. A novel shell element enriched with the Floating Node Method, and a damage algorithm based on the Virtual Crack Closure Technique, were used to successfully simulate the tests. Additionally, a 3D high mesh fidelity model based on cohesive zones and continuum damage mechanics was used to simulate the tests and act as a representative of other similar state-of-the-art high mesh fidelity modeling techniques to compare to the enriched shell element. The enriched shell and high mesh fidelity models had similar levels of accuracy and generally matched the experimental data. With runtimes of 36 minutes for the shell model and 55 hours for the high mesh fidelity model, the shell model is 92 times faster than the high- fidelity simulation

The Processual Ordering of Mental Health Care: The Dramaturgical Styles of Contending Political Factions

The processual ordering branch of symbolic interaction has long recognized the importance of rhetoric and power to the social constitution of reality. However, little systematic effort has been devoted to probing their intertwined effects in the public policy arena. The purpose of this paper is to employ the processual ordering perspective to examine the dramaturgical styles used in shaping public policy -- expressed in terms of the “public administration” and “realpolitik” forms of rhetoric -- among contending political factions as they negotiate mental health public policy. A latent content analysis of the minutes of key U.S. Congressional debates, augmented with secondary archival material from the press is employed. It is concluded that both forms of rhetoric play a role in shaping public mental health policy and that both factions modify their rhetorical form as the debate progresses. Those modifications strengthen the position of one faction while weakening that of the other. Theoretical implications are discussed

Co-occurring internalizing and externalizing psychopathology in childhood and adolescence: a network approach

The network approach suggests that psychopathology arises from complex associations between symptoms and may offer insight into the mechanisms that underpin psychiatric comorbidities. The transition from childhood to adolescence is a key period in the development of psychopathology, yet has rarely been considered from a network perspective. As such, the present study examined the network structure of internalizing and externalizing psychopathology from middle childhood through adolescence using data from the Avon Longitudinal Study of Parents and Children (ALSPAC; n = 4405). Eight DSM-IV disorders were assessed using maternal reports when children were aged 7.5, 10.5 and 14 years. Weighted, undirected networks were estimated and the relative importance of each node was assessed using three common measures of node centrality; strength, betweenness, and closeness. A consistent network structure emerged at all three time points; nodes clustered together in two regions of space broadly reflecting the internalizing and externalizing spectra. Permutation tests supported structural invariance across this developmental period. These spectra were bridged by numerous disorder-level interactions, the most consistent of which was between depression and oppositional defiant disorder (ODD). Furthermore, inspection of the centrality indices indicated that generalised anxiety disorder and ODD were the most central disorders in the networks. These findings demonstrate that symptom/disorder-level interplay and reciprocal influence are plausible mechanisms for the association between internalizing and externalizing psychopathology in childhood/adolescence

A Composite Damage Tolerance Simulation Technique to Augment the Building Block Approach

Aerospace structures comprised of composite materials are traditionally certified empirically via the Building Block Approach (BBA). While this approach has been performed successfully in the past, it is expensive and time consuming. One means to improve the overall efficiency of composite structural certification is to reduce the cost of the BAA by eliminating the need for some tests by incorporating damage analysis tools. For an analysis to replace a given test, the tool must first be validated using other similar test data. The subject of this paper is a description of an analysis technique for simulating compression after damage strength of a solid laminate. The analysis technique is one that is practical for use in an applied engineering context due to efforts to minimize necessary computational resources and complexity of the model

Optimization of an Air Film Cooled CFRP Panel with an Embedded Vascular Network

This paper summarizes research performed on thermodynamic simulation and design optimization of a composite panel cooled by an external cool film and an internal vascular network