Development and verification of global/local analysis techniques for laminated composites

A two-dimensional to three-dimensional global/local finite element approach was developed, verified, and applied to a laminated composite plate of finite width and length containing a central circular hole. The resulting stress fields for axial compression loads were examined for several symmetric stacking sequences and hole sizes. Verification was based on comparison of the displacements and the stress fields with those accepted trends from previous free edge investigations and a complete three-dimensional finite element solution of the plate. The laminates in the compression study included symmetric cross-ply, angle-ply and quasi-isotropic stacking sequences. The entire plate was selected as the global model and analyzed with two-dimensional finite elements. Displacements along a region identified as the global/local interface were applied in a kinematically consistent fashion to independent three-dimensional local models. Local areas of interest in the plate included a portion of the straight free edge near the hole, and the immediate area around the hole. Interlaminar stress results obtained from the global/local analyses compares well with previously reported trends, and some new conclusions about interlaminar stress fields in plates with different laminate orientations and hole sizes are presented for compressive loading. The effectiveness of the global/local procedure in reducing the computational effort required to solve these problems is clearly demonstrated through examination of the computer time required to formulate and solve the linear, static system of equations which result for the global and local analyses to those required for a complete three-dimensional formulation for a cross-ply laminate. Specific processors used during the analyses are described in general terms. The application of this global/local technique is not limited software system, and was developed and described in as general a manner as possible

A Budgetary Life Raft: An Analysis of Louisiana\u27s State and Local Sales Tax

The article discusses the state and local sales taxes in Louisiana, including their history, functions in local government administration, as well as the exemptions and exclusions

Composite materials for rail transit systems

The potential is explored for using composite materials in urban mass transit systems. The emphasis was to identify specific advantages of composite materials in order to determine their actual and potential usage for carbody and guideway structure applications. The literature was reviewed, contacts were made with major domestic system operators, designers, and builders, and an analysis was made of potential composite application to railcar construction. Composites were found to be in use throughout the transit industry, usually in secondary or auxiliary applications such as car interior and nonstructural exterior panels. More recently, considerable activity has been initiated in the area of using composites in the load bearing elements of civil engineering structures such as highway bridges. It is believed that new and improved manufacturing refinements in pultrusion and filament winding will permit the production of beam sections which can be used in guideway structures. The inherent corrosion resistance and low maintenance characteristics of composites should result in lowered maintenance costs over a prolonged life of the structure

Christianity and Critical Race Theory: A Flirtation with the Spirit of this Age

Critical Race Theory is sweeping across the country, changing the way people see the world and creating its own version of American history. Critical Race Theory proclaims a different path towards “freedom” and “liberation”, yet it is a mirage, and the tactics they use to fight the systemic racism in the United States only produce more racism. Key terms like intersectionality and racial equity are used to describe how they plan to dismantle hierarchies and racism, yet these ideas are not what they seem at first glance. Critical Race Theory is a worldview that is not just about race: it is a lifestyle that answers key questions about who we are, what is wrong with the world, and how we can fix it. Yet, these answers are antithetical to the Christian Worldview

The Effects of Parent Training and Information Centers on Parent Empowerment

Parents of children who receive special education services from the public school are considered equal partners in their child’s education with school professionals on the Individual Education Program team. Each state has a Parent Training and Information Center (PTIC) that seeks to empower parents to fulfill their right as an equal partner. The current study compared the advocacy, knowledge, competence, self-efficacy, and empowerment of two groups of parents of children with disabilities who received special education services in Tennessee. The experimental group of parents (n=36) had attended a workshop provided by a PTIC and the control group (n=21) had not attended a workshop. Participants received an email from PTIC with a link to the survey or received a hard copy of the survey at a workshop. The survey included demographic information, Likert-scale questions, and open-ended questions about parents’ experiences and suggestions for improvement from the Family Empowerment Scale (Koren, DeChillo, & Friesen, 1992) and the Fish survey (2008). Quantitative results from the likert-scale questions about parent advocacy (p=.847), knowledge (p=.117), competence (p=.669), self-efficacy (p=.992), and empowerment (p=.459) were not statistically significant. Parent responses to the open-ended questions aligned with a current literature review and emphasized the importance of educating themselves about the special education process, being an involved and equal partner on the Individual Education Program team, and communicating regularly with school professionals

Contextualising Nanotechnology in Chemistry Education

This paper will give an example of a pedagogical approach taken in integrating nanotechnology into a chemistry degree course. In recent years nanotechnology has widely become part of the course content for undergraduate chemistry and physics degree curriculum. How contextualised the delivery of the subject matter may vary. The role of contextualisation of nanotechnology in the delivery of the content is the main focus of this paper, as to date in Ireland and many other countries nanotechnology has not been integrated into many chemistry degree courses but is slowly becoming the case. An evaluative methodology of the pedagogical approach for two introductory nanotechnology courses has been chosen for this study. Pre and post-course testing at a 4th year level and 2nd year level have been carried out and the feedback summarised. The role of visualisation and contextualisation (linking research and industrial applications to the area) will be discussed in relation to learning and teaching nanotechnology. The benefits of using nanochemistry and nanotechnology can be highlighted and this may be linked to an examination of existing applications in everyday life. It is hoped that this paper will stimulate some ideas for academics who may find themselves faced with teaching nanotechnology in the near future

Development and verification of local/global analysis techniques for laminated composites

Analysis and design methods for laminated composite materials have been the subject of considerable research over the past 20 years, and are currently well developed. In performing the detailed three-dimensional analyses which are often required in proximity to discontinuities, however, analysts often encounter difficulties due to large models. Even with the current availability of powerful computers, models which are too large to run, either from a resource or time standpoint, are often required. There are several approaches which can permit such analyses, including substructuring, use of superelements or transition elements, and the global/local approach. This effort is based on the so-called zoom technique to global/local analysis, where a global analysis is run, with the results of that analysis applied to a smaller region as boundary conditions, in as many iterations as is required to attain an analysis of the desired region. Before beginning the global/local analyses, it was necessary to evaluate the accuracy of the three-dimensional elements currently implemented in the Computational Structural Mechanics (CSM) Testbed. It was also desired to install, using the Experimental Element Capability, a number of displacement formulation elements which have well known behavior when used for analysis of laminated composites

Computational mechanics needs study

In order to assess the needs in computational mechanics over the next decade, we formulated a questionnaire and contacted computational mechanics researchers and users in industry, government, and academia. As expected, we found a wide variety of computational mechanics usage and research. This report outlines the activity discussed with those contacts, as well as that in our own organizations. It should be noted that most of the contacts were made before the recent decline of the defense industry. Therefore, areas which are strongly defense-oriented may decrease in relative importance. In order to facilitate updating of this study, names of a few key researchers in each area are included as starting points for future literature surveys. These lists of names are not intended to represent those persons doing the best research in that area, nor are they intended to be comprehensive. They are, as previously stated, offered as starting points for future literature searches. Overall, there is currently a broad activity in computational mechanics in this country, with the breadth and depth increasing as more sophisticated software and faster computers become more available. The needs and desires of the workers in this field are as diverse as their background and organizational products. There seems to be some degree of software development in any organization (although the level of activity is highly variable from one organization to another) which has any research component in its mission. It seems, however, that there is considerable use of commercial software in almost all organizations. In most industrial research organizations, it appears that very little actual software development is contracted out, but that most is done in-house, using a mixture of funding sources. Government agencies vary widely in the ratio of in-house to out-house ratio. There is a considerable amount of experimental verification in most, but not all, organizations. Generally, the amount of experimental verification is more than we expected. Of all the survey contacts, one or two believe that the resources they are allocated are sufficient, but most do not. Some believe they have only half the resources they need. Some see their resource deficits as short-term, while others see it as a trend which will continue or perhaps worsen. The pessimism is stronger in the defense and aerospace industry. When considering only the nonlinear development efforts, there appears to be an even mix of geometric and material nonlinearity. There is not much particular emphasis in linear analysis unless it is in extension of current analysis capabilities to larger problems. The primary exception is concern about modeling of composites, where proven methodologies have trailed element and computer hardware development. Most of the people we spoke to use finite element techniques, but there is some finite difference and boundary element work ongoing. There is also some interest in multiple methods. Coupling of finite elements and boundary elements appears to be of high interest, since the two analysis types are complementary