Further generalization of an equivalent plate representation for aircraft structural analysis

Recent developments from a continuing effort to provide an equivalent plate representation for aircraft structural analysis are described. Previous work provided an equivalent plate analysis formulation that is capable of modeling aircraft wing structures with a general planform such as cranked wing boxes. However, the modeling is restricted to representing wing boxes having symmetric cross sections. Further developments, which are described, allow modeling of wing cross sections having asymmetries that can arise from airfoil camber or from thicknesses being different in the upper and lower cover skins. An implementation of thermal loadings, which are described as temperature distributions over the planform of the cover skins, has been included. Spring supports have been added to provide for a more general set of boundary conditions. Numerical results are presented to assess the effect of wing camber on the static and dynamic response of an example wing structure under pressure and thermal loading. These results are compared with results from a finite element analysis program to indicate how well a cambered wing box can be represented with an equivalent plate formulation

Design oriented structural analysis

Desirable characteristics and benefits of design oriented analysis methods are described and illustrated by presenting a synoptic description of the development and uses of the Equivalent Laminated Plate Solution (ELAPS) computer code. ELAPS is a design oriented structural analysis method which is intended for use in the early design of aircraft wing structures. Model preparation is minimized by using a few large plate segments to model the wing box structure. Computational efficiency is achieved by using a limited number of global displacement functions that encompass all segments over the wing planform. Coupling with other codes is facilitated since the output quantities such as deflections and stresses are calculated as continuous functions over the plate segments. Various aspects of the ELAPS development are discussed including the analytical formulation, verification of results by comparison with finite element analysis results, coupling with other codes, and calculation of sensitivity derivatives. The effectiveness of ELAPS for multidisciplinary design application is illustrated by describing its use in design studies of high speed civil transport wing structures

Effects of nonlinear aerodynamics and static aeroelasticity on mission performance calculations for a fighter aircraft

During conceptual design studies of advanced aircraft, the usual practice is to use linear theory to calculate the aerodynamic characteristics of candidate rigid (nonflexible) geometric external shapes. Recent developments and improvements in computational methods, especially computational fluid dynamics (CFD), provide significantly improved capability to generate detailed analysis data for the use of all disciplines involved in the evaluation of a proposed aircraft design. A multidisciplinary application of such analysis methods to calculate the effects of nonlinear aerodynamics and static aeroelasticity on the mission performance of a fighter aircraft concept is described. The aircraft configuration selected for study was defined in a previous study using linear aerodynamics and rigid geometry. The results from the previous study are used as a basis of comparison for the data generated herein. Aerodynamic characteristics are calculated using two different nonlinear theories, potential flow and rotational (Euler) flow. The aerodynamic calculations are performed in an iterative procedure with an equivalent plate structural analysis method to obtain lift and drag data for a flexible (nonrigid) aircraft. These static aeroelastic data are then used in calculating the combat and mission performance characteristics of the aircraft

Sensitivity-based scaling for correlating structural response from different analytical models

A sensitivity-based linearly varying scale factor is described used to reconcile results from refined models for analysis of the same structure. The improved accuracy of the linear scale factor compared to a constant scale factor as well as the commonly used tangent approximation is demonstrated. A wing box structure is used as an example, with displacements, stresses, and frequencies correlated. The linear scale factor could permit the use of a simplified model in an optimization procedure during preliminary design to approximate the response given by a refined model over a considerable range of design changes

The Role of Databases in Areawide Pest Management

The simplest definition of the term \u27database\u27 is given in Webster\u27s dictionary as \u27a comprehensive collection of related data organized for convenient access, generally in a computer\u27 (Random House, 1996). This term appeared in the late 1960s because of the evolution of computer software and the need to distinguish the specialized computer systems for the storage and manipulation of data, called database management systems (DBMS) (Neufeld and Cornog, 1986). Today, the acronym \u27DBMS\u27 is universally understood within Information Technology (IT), just like the acronym \u27Bt\u27 for \u27Bacillus thuringiensis\u27 is in the field of biological pest control. At the present time there are numerous DBMS products available on the market. The most popular are Oracle©, dBase©, DB2©, MS SQL Server© and Access©. Access is a part of the Microsoft Office product and can be considered as a prototype of DBMS with limited functionality. These products vary in price and capacity, and therefore the budgetary constraints and the requirements of a particular database application determine their utility. The evolution of database products has been rapid, reflecting advances in the theory of databases during the last 35-40 years. Beginning with simple data files with direct access, these database products now include very sophisticated file systems with complex interrelationships. More recently, there has been a series of new database applications named Relational Database Management Systems (RDBMS). Their development was a product of the advancement in IT, which forced DBMS to adapt. One of these advancements was the creation of distributed computer systems using local or wide-area networks (LAN/WAN) at the end of the 1980s and early 1990s (Date, 2003). These networks stimulated development of new methods for remote database connection, and the improvements of client/server technologies when databases are organized on a computer server separated from those remotely accessed and used to enter data. The uses of DBMS can be very diverse, but this chapter focuses on the application of DBMS in the field of biology, more specifically in entomology and integrated pest management (IPM)

The Role of Databases in Areawide Pest Management

The simplest definition of the term \u27database\u27 is given in Webster\u27s dictionary as \u27a comprehensive collection of related data organized for convenient access, generally in a computer\u27 (Random House, 1996). This term appeared in the late 1960s because of the evolution of computer software and the need to distinguish the specialized computer systems for the storage and manipulation of data, called database management systems (DBMS) (Neufeld and Cornog, 1986). Today, the acronym \u27DBMS\u27 is universally understood within Information Technology (IT), just like the acronym \u27Bt\u27 for \u27Bacillus thuringiensis\u27 is in the field of biological pest control. At the present time there are numerous DBMS products available on the market. The most popular are Oracle©, dBase©, DB2©, MS SQL Server© and Access©. Access is a part of the Microsoft Office product and can be considered as a prototype of DBMS with limited functionality. These products vary in price and capacity, and therefore the budgetary constraints and the requirements of a particular database application determine their utility. The evolution of database products has been rapid, reflecting advances in the theory of databases during the last 35-40 years. Beginning with simple data files with direct access, these database products now include very sophisticated file systems with complex interrelationships. More recently, there has been a series of new database applications named Relational Database Management Systems (RDBMS). Their development was a product of the advancement in IT, which forced DBMS to adapt. One of these advancements was the creation of distributed computer systems using local or wide-area networks (LAN/WAN) at the end of the 1980s and early 1990s (Date, 2003). These networks stimulated development of new methods for remote database connection, and the improvements of client/server technologies when databases are organized on a computer server separated from those remotely accessed and used to enter data. The uses of DBMS can be very diverse, but this chapter focuses on the application of DBMS in the field of biology, more specifically in entomology and integrated pest management (IPM)

Interplay of Turbulence and Proton-Microinstability Growth in Space Plasmas

Both kinetic instabilities and strong turbulence have potential to impact the behavior of space plasmas. To assess effects of these two processes we compare results from a 3 dimensional particle-in-cell (PIC) simulation of collisionless plasma turbulence against observations by the MMS spacecraft in the terrestrial magnetosheath and by the Wind spacecraft in the solar wind. The simulation develops coherent structures and anisotropic ion velocity distributions that can drive micro-instabilities. Temperature-anisotropy driven instability growth rates are compared with inverse nonlinear turbulence time scales. Large growth rates occur near coherent structures; nevertheless linear growth rates are, on average, substantially less than the corresponding nonlinear rates. This result casts some doubt on the usual basis for employing linear instability theory, and raises questions as to why the linear theory appears to work in limiting plasma excursions in anisotropy and plasma beta.Comment: Under revie

Do social networks affect the use of residential aged care among older Australians?

Background: Older people's social networks with family and friends can affect residential aged care use. It remains unclear if there are differences in the effects of specific (with children, other relatives, friends and confidants) and total social networks upon use of low-level residential care and nursing homes. Methods: Data were drawn from the Australian Longitudinal Study of Ageing. Six waves of data from 1477 people aged ≥ 70 collected over nine years of follow-up were used. Multinomial logistic regressions of the effects of specific and total social networks on residential care use were carried out. Propensity scores were used in the analyses to adjust for differences in participant's health, demographic and lifestyle characteristics with respect to social networks. Results Higher scores for confidant networks were protective against nursing home use (odds ratio [OR] upper versus lower tertile of confidant networks = 0.50; 95%CI 0.33–0.75). Similarly, a significant effect of upper versus lower total network tertile on nursing home use was observed (OR = 0.62; 95%CI 0.43–0.90). Evidence of an effect of children networks on nursing home use was equivocal. Nursing home use was not predicted by other relatives or friends social networks. Use of lower-level residential care was unrelated to social networks of any type. Social networks of any type did not have a significant effect upon low-level residential care use. Discussion: Better confidant and total social networks predict nursing home use in a large cohort of older Australians. Policy needs to reflect the importance of these particular relationships in considering where older people want to live in the later years of life.Lynne C Giles, Gary FV Glonek, Mary A Luszcz and Gary R Andrew