ISSN:0272-8397    

DOI:10.1002/pc.750090502

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThin, orthotropic fiber‐reinforced composite laminae under plane stress loading conditions are considered. The essential conditions that must be satisfied in developing phenomenological strength criteria for such materials are first established. A new, parametric failure criterion is then presented. It is shown that this entirely general formulation encompasses all previously proposed failure theories (e.g., tensor polynomial criterion) for orthotropic laminae. Examples of application and the inherent advantages and drawbacks of the proposed parametric approach are discussed. In the past, the formulation of strength criteria for composite materials has closely paralleled the development of yield criteria in metal plasticity. The parametric approach advocated here for the failure of composite materials was inspired by a general formulation proposed by Budiansky (1) for the plastic yielding of sheet metal

ISSN:0272-8397    

DOI:10.1002/pc.750090503

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractFour commercially available carbon fiber/prepreg systems were processed and subjected to NASA's proposed standard tests for toughened resins. Narmco Materials Inc. Rigidite T300/5208 was included as a baseline, while the other three systems employed Hercules' IM6 fiber in newgeneration resin systems. Descriptions of the tests, including open‐hole tension and compression, compression after impact, double cantilever beam, and edge delamination tension, as well as results are presente

ISSN:0272-8397    

DOI:10.1002/pc.750090504

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractLow‐energy instrumented falling weight impact tests were used to study the failure mechanisms in various multiangle laminates of continuous carbon‐fiber‐reinforced composites. C‐scans of impacted specimens were conducted to monitor an area for delamination damage. Photography of the tension surface during impact enabled the onset of tension surface cracking to be detected. These techniques were employed for composites based on thermoplastic, poly(ether ether ketone) (PEEK), and thermoset (epoxy system 934) matrix materials. In addition, a range of ply numbers (8 to 40) were used in preparation of the multiangle laminates. Tension surface splitting can be shown to be the first failure mechanism during impact. Initiation of a tension crack occurs at a lower absorbed impact energy than that for the onset of delamination

ISSN:0272-8397    

DOI:10.1002/pc.750090505

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractTapered laminates of unidirectional layers of glass/epoxy and graphite/epoxy are investigated. These laminates have a thickness variation along their length. This was accomplished by having layers dropped off near the midlength of the laminate. Stress and strain variations were obtained using three‐dimensional finite element models. Calculated values using the finite element method compare well with experimental results for the point of first delamination. This agreement allows the determination of a suitable finite element mesh for subsequent models of other tapered laminates with fiber orientations other than unidirectiona

ISSN:0272-8397    

DOI:10.1002/pc.750090506

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractAcoustic emission (AE) was used to monitor damage development in a glass fiber/epoxy composite during monotonic and cyclic Mode II loadings of DCB specimens. AE parameters such as event count rates and accumulative event counts together with the distribution of events by time and location in the DCB specimen were used as proper indicators of the damage growth at various stages during testing. AE proved to be a powerful technique to predict in real time the interlaminar failure stress (delamination in Mode II) in both the static and the dynamic tests. AnS‐Ncurve constructed entirely on the AE signatures recorded during fatigue testing exhibits three distinct stages enabling delineation of period of damage initiation, the period of damage growth, and finally the occurrence of delamination. A generalized expression based on the nonlinear cumulative damage model was developed to correlate AE activity with the damage development in the composite during cyclic loading. The fatigue data to date agree well with this method of prediction of the fatigue lif

ISSN:0272-8397    

DOI:10.1002/pc.750090507

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractA summary of the simple to very complex fiber composite components that have been fabricated by automated filament winding is presented. The process of filament winding, where resin‐impregnated, high strength, high modulus fibers are placed on a rotating mandrel (under controlled tension) in a specified geometric pattern, is then described in detail. A qualitative comparison of the filament winding of fiber composite components by conventional and robotic winding systems is presented next. The results indicate that a robotic winding system can be a viable alternative to conventional filament winding for certain applications. Finally, the concepts of lightweight winding systems, hybrid filament winding processes, and advanced filament winding techniques are presente

ISSN:0272-8397    

DOI:10.1002/pc.750090508

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe effect of silane coupling agent on the morphology and fracture performance of particulates‐filled polypropylene was investigated. The onset of the crystallization at the filler‐matrix interface was observed by optical microscopy. This analysis shows that the silane alters the matrix morphology by inducing nucleation at the filler‐matrix interface. This effect was attributed to the physisorbed layer of silane on the filler. The fracture performance of the composites was analyzed by the post yield fracture mechanics approach. The effect of coupling agent on the fracture performance was found to occur at a very low concentration, whereas subsequent increase in silane concentration had no effect. Furthermore, the effect of coupling agent depended on concentration of filler. Silane treatment had a detrimental effect at low concentration of filler. However, at high concentration of filler, an improvement in the filler‐matrix adhesion had a beneficial effect on the fracture performance. Two phenomena, the morphological effect and the competition between the contribution of the matrix‐filler interface and the contribution of the matrix, were found to be possible explanations for the variation ofKRmaxwith filler concentration and adhesion at the matrix‐fille

ISSN:0272-8397    

DOI:10.1002/pc.750090509

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractHydrodynamic lubrication theory has been applied to analyze flow in internal mixers and twin‐screw extruders. Fluid motions in mixing regions are interpreted as being due to coupling of drag flow and pressure gradients. Pressure fields and mean flow patterns have been computed. Distributive and dispersive mixing are interpreted in terms of computed fluid fluxes in the processing machiner

ISSN:0272-8397    

DOI:10.1002/pc.750090510

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

ISSN:0272-8397    

DOI:10.1002/pc.750090501

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY