ISSN:0032-3888    

DOI:10.1002/pen.760280902

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper discusses the cost of high technology and its benefits to commercial air transportation. The manufacturer's dilemma today is that, while one could pay a 16 percent price premium to obtain a 10 percent reduction in fuel cost in the late 1970s, in 1985 that price premium has diminished to only 2‐1/2 percent to achieve a 10 percent fuel saving. Consequently, we must obtain the benefits of high technology at an extremely low cost. Four areas are discussed in some depth: Aerodynamics, including the effects of computational fluid dynamics, wing design, and laminar flow; structures, including the effects of new materials, both metallic and nonmetallic, and the automated tools necessary to build the nonmetallic structure; avionics, including both fly‐by‐wire and fly‐by‐light, and the improvements due to high‐speed digital computers as well as flat panel flight deck displays; and propulsion systems, including the effects of high‐bypass ratio, high‐pressure ratio turbofan engines, and single and counter rotation turbopropellers. The final result is an integration of these four areas of technology into a composition transport aircraft and the result

ISSN:0032-3888    

DOI:10.1002/pen.760280903

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractAn epoxy resin and a sized carbon fiber have been used to produce a light‐weight filament wound case for the Space Shuttle. The sizing facilitates fiber handling during winding but may affect the amount of resin absorbed by the fiber during impregnation and the final mechanical properties of the composite. Naval Ordnance Lab rings were wound to study the effect of the sizing content on the resin absorption by the fiber bundles, the final tensile properties of the composite, and the type of failure observed at burst. The resin content of the rings studied was between 20 to 40 percent, and the sizing content, 0 to 1.6 percent by weight. Results showed that the sizing content was a critical parameter which determined the amount of resin absorbed by the fibers. The final tensile strength was dependent on the amount of sizing present. The tensile strength decreased by as much, as 60 percent when a low resin and high sizing content were present. The type of failure at burst was a function of resin content rather than size conten

ISSN:0032-3888    

DOI:10.1002/pen.760280904

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractOxidized carbon fibers were coated using an on‐line filament winding process with an elastomeric adduct crosslinkable and compatible with an epoxy matrix. The coating and modifications of the epoxy network were studied by dynamic mechanical measurements. Assuming that apparent activation energies of the secondary relaxation βeof the epoxy network and main relaxation αaof adduct are very different, it is possible at low frequencies to separate the two peaks. The composite material can be described as a three phase system: an epoxy network as matrix, carbon fibers, and a soft interlayer. The mechanical behavior of unidirectional composite materials studied by impact and bending tests is strongly dependent on the presence and the thickness of the coating at the carbon fiber surf

ISSN:0032-3888    

DOI:10.1002/pen.760280905

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper describes the utility of Torsion Impregnated Cloth Analysis, a very versatile technique to characterize resin behavior during cure or after repeated thermal and environmental treatment. Multi‐frequency scan data have been shown to help tremendously in interpreting the behavior during experimentation. The technique is also very useful in defining the cure conditions for new resin chemistry/system

ISSN:0032-3888    

DOI:10.1002/pen.760280906

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractAn analytical methodology was developed capable of describing interrelations between thermal processing and polymer structure for thermoplastic based composite laminates. Specifically, this modeling methodology was used to describe experimental results generated with a specially designed match die quench mold by processing both neat PEEK polymer and carbon fiber reinforced laminate samples at different cooling rates. The developed model accurately predicted temperature profiles for PEEK laminates of different thicknesses, under normal as well as extreme quenching conditions of 114°C/s. surface cooling rates that are possible to generate with the quench mold. In general, the modeling methodology is capable of predicting a part's thermal profile during processing in terms of the composite's microscopic intrinsic properties (fiber and matrix), composition, and lamina orientation. Furthermore, by coupling to the thermal profile description, a previously developed crystallization kinetics model for PEEK polymer and its carbon reinforced composite, a quantitative description of structural development during processing was obtained. Thus, with this analytical methodology, a skin‐core crystallinity profile, where the crystallinity varies with part‐thickness as a result of uneven cooling experienced during processing, was predicted both for the neat PEEK polymer and its carbon reinforced laminate forms. Finally, the developed methodology clearly established the interplay of both microscopic heat transfer and kinetics of crystallization/solidification of the matrix that must be accounted for in predicting the final structure of a carbon fiber reinforced laminate that will, in turn, govern microscopic and macroscopic perform

ISSN:0032-3888    

DOI:10.1002/pen.760280907

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractA computer controlled test procedure for evaluating mode I and mode II interlaminar fracture behavior was used in experiments with eight different resin matrix/graphite fiber composites. Four analytical methods for calculating fracture toughness were compared. These included an energy rate determination of theJ‐integral, a compliance calibration procedure, equations based on linear beam bending, and an Area method calculation. Methods that account for nonlinear material behavior, such as theJ‐integral, were needed for characterizing the systems with high fracture toughness. The ratio of mode II to mode I fracture toughness ranged from 1.5 to 8.0, depending on the material system. Finally, preliminary work with a technique for constant strain rate testing of mode I DCB specimens is presen

ISSN:0032-3888    

DOI:10.1002/pen.760280908

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe static delamination behavior of graphite/epoxy composite specimens subjected to mode I tensile opening (using UDCBUniform double cantilever beam.specimens), and pure mode II shear loading (using ENFEnd‐notched flexural.specimens) were studied. The graphite epoxy composites for the study were made from commercially treated fibers, with and without an electropolymerized interlayer. The mode I fracture energy (GIC) was found to be significantly higher (more than 50 percent) for the coated fibers. However, this improvement was accompanied by a high reduction (more than 3 times) in the mode II fracture energy (GIIC). This effect is apparently related to poor adhesion between the interlayer and the epoxy resin, which may be corrected by use of a “top layer” of appropriate composition to form chemical bonds between the phases. The fracture toughness (KIC) of composites made with commercially treated fibers was also evaluated, using double side‐notched sp

ISSN:0032-3888    

DOI:10.1002/pen.760280909

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe influence of the hard or soft inclusions and the mesophase layers in either a soft‐hard‐soft or hard‐soft‐hard combination of biphase plates submitted to dynamic tensile loads on the fracture mode and bifurcation process in both phases was investigated in this paper. It was assumed that the soft or hard matrix is infolding the hard or soft inclusion of the plate, so that the plate constitutes a meridional section of the representative volume element of a unidirectional fiber composite, or a principal section of a particulate. The influence of the mechanical properties of either phase on the crack propagation velocity and the initiation of crack bifurcation was studied by using high‐speed photography and dynamic caustics. The results showed that the propagating crack tended to bifurcate either in the brittle or in the mesophase layer under certain conditions of propagation velocity. It was shown that bifurcation of a propagating crack depends on the elastic moduli and Poisson's ratios of the phases, as well as on the extent of the mesophase layer, which depended on the adhesion quality

ISSN:0032-3888    

DOI:10.1002/pen.760280910

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractInstrumented falling weight impact is conducted on eight different continuous carbon fiber composites. During impact, photography of the tension surface of the specimens enables crack propagation to be monitored. One photograph per specimen is taken. Measurements of integral crack length is related to corresponding absorbed energies during impact. These results enable an apparent value ofGcto be determined. These are tabulated for the eight advanced composite samples.

ISSN:0032-3888    

DOI:10.1002/pen.760280911

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY