Composites: A viable option

While it sounded great to be asked to talk about composites, I found it difficult to select subject areas that would be of real interest. My choice is based on saying some things about where the maturity of the composite aircraft structures is today and what that means in terms of future criteria for application. This focus was the basis for my title selection. The other issue that will be addressed was requested by NASA and focuses on composites structures cost. This fits well with the state-of-the-art interpretations I will discuss first, since the cost issue must be viewed from both the current status and future points of view. The difficulty in presenting something in these areas is not in the subjects themselves but in trying to present a real world viewpoint to an audience of composite experts. So, with recognition of the expertise of the audience, I hope you will see something in this presentation about how to view composite aircraft structure

Preliminary weight and costs of sandwich panels to distribute concentrated loads

Minimum mass honeycomb sandwich panels were sized for transmitting a concentrated load to a uniform reaction through various distances. The form skin gages were fully stressed with a finite element computer code. The panel general stability was evaluated with a buckling computer code labeled STAGS-B. Two skin materials were considered; aluminum and graphite-epoxy. The core was constant thickness aluminum honeycomb. Various panel sizes and load levels were considered. The computer generated data were generalized to allow preliminary least mass panel designs for a wide range of panel sizes and load intensities. An assessment of panel fabrication cost was also conducted. Various comparisons between panel mass, panel size, panel loading, and panel cost are presented in both tabular and graphical form

Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 3: Major component development

Analytical and experimental investigations, performed to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites, are reported. Aluminum-boron-epoxy and titanium-boron-epoxy were used in the design and manufacture of three major structural components. The components were representative of subsonic aircraft fuselage and window belt panels and supersonic aircraft compression panels. Both unidirectional and multidirectional reinforcement concepts were employed. Blade penetration, axial compression, and inplane shear tests were conducted. Composite reinforced structural components designed to realistic airframe structural criteria demonstrated the potential for significant weight savings while maintaining strength, stability, and damage containment properties of all metal components designed to meet the same criteria

Durability and damage tolerance of Large Composite Primary Aircraft Structure (LCPAS)

Analysis and testing addressing the key technology areas of durability and damage tolerance were completed for wing surface panels. The wing of a fuel-efficient, 200-passenger commercial transport airplane for 1990 delivery was sized using graphite-epoxy materials. Coupons of various layups used in the wing sizing were tested in tension, compression, and spectrum fatigue with typical fastener penetrations. The compression strength after barely visible impact damage was determined from coupon and structural element tests. One current material system and one toughened system were evaluated by coupon testing. The results of the coupon and element tests were used to design three distinctly different compression panels meeting the strength, stiffness, and damage-tolerance requirements of the upper wing panels. These three concepts were tested with various amounts of damage ranging from barely visible impact to through-penetration. The results of this program provide the key technology data required to assess the durability and damage-tolerance capability or advanced composites for use in commercial aircraft wing panel structure

Transition services and their effectiveness

The purpose of this study was to determine if transition services as they are currently performed in a large suburban regional high school district are effective in helping classified students make the transition to the world beyond high school. A review of current literature on transition shows that services vary in scope and effectiveness from state to state and from district to district. Interviews with district personnel reveal no follow-up once a student has left the district through graduation or aging out. A survey instrument was compiled and mailed to 200 former students who were classified while attending school in the district. The survey sought information on the transition conference, help from local, state and private agencies and their feelings regarding the help they received from district personnel. The results of the survey were mixed with the district doing a good job overall and the state needing to improve its help of these young people

Introduction to the adhesive bonding session

Space shuttle unique requirements call for the development of a specific adhesive system to reliable attach reusable surface insulation. A low density foam system has been developed that provides strain isolation from the support structure and remains structurally stable in space shuttle thermal environment. Surface preparation and its stabilization by an adhesive primer system are the most important factors in preventing corrosion from reducing the reliability and durability of the adhesive bonding component

The center of the universe: A ceremony at Pipe Spring Sweat Lodge

The Sweat Lodge at Pipe Spring is a healing place for many people. The spiritual leader of the lodge is a Southern Paiute man who conducts open ceremonies so that all people may participate in the process of cleansing body and spirit. The ritual process brings together the positive effects of group interaction and fosters spiritual growth for individuals and the group. The Lakota style sweat lodge ceremony was introduced by an Assiniboine man and the ceremony has incorporated Paiute and Christian elements through cultural adaptations. Though the ceremony has been borrowed and has undergone some changes, its effectiveness as a place of spiritual and physical healing remains strong

Explicit solution techniques for impact with contact constraints

Modern military aircraft transparency systems, windshields and canopies, are complex systems which must meet a large and rapidly growing number of requirements. Many of these transparency system requirements are conflicting, presenting difficult balances which must be achieved. One example of a challenging requirements balance or trade is shaping for stealth versus aircrew vision. The large number of requirements involved may be grouped in a variety of areas including man-machine interface; structural integration with the airframe; combat hazards; environmental exposures; and supportability. Some individual requirements by themselves pose very difficult, severely nonlinear analysis problems. One such complex problem is that associated with the dynamic structural response resulting from high energy bird impact. An improved analytical capability for soft-body impact simulation was developed

Evidence for a glycolate transporter in the envelope of pea chloroplasts

AbstractGlycolate excretion by chloroplasts is essential to the process of photorespiration. Previous transport studies on intact chloroplasts have failed to find evidence for carrier-mediated transport of glycolate. The rate of glycolate uptake, when measured by a rapid silicone oil centrifugation method, saturates at high glycolate concentrations. This rapid glycolate uptake is inhibited by pretreatment of the chloroplasts with N-ethylmaleimide, an inhibition prevented by glycolate. Glyoxylate and glycerate inhibit glycolate uptake when present in the assay medium. These results suggest the existence of a glycolate transporter in the chloroplast envelope