Advanced Techniques of Analysis and Testing of Composites for Aerospace Applications

This special issue of the Journal of Aerospace Engineering contains a collection of invited papers written by experts working in various areas of composite materials and structures. Some of these papers are based on the presentations delivered in the ‘‘Advanced Composite Materials for Civil/Aerospace Engineering Applications’’ session organized by the ASCE Aerospace Division’s Committee on Advanced Composite Materials at the 2001 SDM Conference. The diversity of topics addressed in this special issue deal not only with composite materials and structure, but other fundamental mechanics applications to aircraft/aerospace analysis and design problems. This reflects the broad interests of the committee’s members. The papers address various rapidly growing areas in aerospace/aircraft applications of composite materials and structures, as well as the development of analytical/numerical techniques in support of test methods. The addressed topics include multiscale modeling of composite materials, material parameter estimation for isotropic and anisotropic materials, use of smart materials in vibration damping, development of analysis techniques and test methodologies for impact testing of aircraft engine components and high speed testing of aircraft/aerospace vehicles, and newly emerging lattice structures, as described in more detail later. Bednarcyk and Arnold present a comprehensive multiscale analysis for the response of metal matrix composites and apply it to a particular material system. The analysis combines micromechanical predictions for the individual ply response within the lamination theory analysis at each loading step. The effects of matrix inelasticity and local damage mechanisms such as fiber breakage/debonding and fatigue-induced matrix damage are taken into account. They developed micromechanics-based methodology which is an important step in utilizing the power of micromechanics to predict failure and fatigue life of metal matrix composites. In the paper by Saleeb et al., the writers present a strategy for estimating material parameters using experimental test data and a chosen constitutive material model. The class of admissible constitutive materials includes some recent viscoplastic and damage models. The procedure which consists of three stages, namely analysis, sensitivity and optimization modules, is implemented through a computer program. The method’s effectiveness is demonstrated through the use of specific experimental data, which reflects different observed material behavior. The use of smart sensors and actuators in active vibration damping of composite beams is the topic of the paper by Song et al. The writers present two approaches for active vibration control of laminated composite beams based on positive and strain rate feedback control algorithms. The experiments that demonstrate the utility of these algorithms are supported by analytical and numerical analyses of the beam response. The paper by Roberts et al. is a conceptoriented contribution in which the writers develop a methodology for evaluating different design concepts for aircraft engine fan cases, taking into account potential failure modes due to impact damage. Experimental impact data are supplemented by numerical analyses of impacted composite panels in order to identify appropriate specimen designs and related failure modes, and offer potential solutions to minimizing impact-induced damage. The results indicate that composite materials are viable candidates for use in aircraft engine fan cases when impact is a limiting design parameter. In the paper by Kocher et al., the writers investigate selected failure modes of a new generation of structural components, known as lattice structures, and how such modes impact the design of these structures. These structures consist of sandwich panels reinforced with truss members in the core. Simple analytical approaches are employed to focus on designs that lead to particular failure modes, and these are further investigated using the finite-element method. Both the topic and the generated results complement the current material/structural development efforts for advanced aircraft/aerospace applications. Finally, Baker et al. develop a model and an analysis technique for a practical problem of rail heating of the Air Force’s high-speed test track facility. This model demonstrates the importance of including temperature fields when analyzing the response of rails subjected to impact loading induced by high-velocity vehicles.