The Effect of Warp and Filling Variables on the Tensile Failure and Joint Strength of Kevlar® 29 Parachute .Webbing

Ericksen, R.H.; Abbott, Norman J.; Donovan, J.G.; Coskren, Robert J.

doi:10.1177/004051757904900101

Cited by 6 publications

(4 citation statements)

References 1 publication

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“…Optimum fabric strength is predicted to occur at warp yarn twist levels lower than those predicted from conventional yarn data.. ; ,, 4. Results of the simulation tests correlate generally, with trends observed in woven structures in constructions where the warp yarns are compressed…”

Section: Mplications Of Simulation Results In Warpmentioning

confidence: 66%

A Technique for Simulating the Stength of Kevlar 29 Yarn in a Woven Configuration

Ericksen¹

1979

Textile Research Journal

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To obtain maximum yarn strength translational efficiency in Kevlar 29 parachute webbings, the pick frequency must be reduced to the extent that the structure is too loose to be useable. As a result only modest efficicncy has been achieved in Kevlar 29 webbings. It has been shown that only part of the strength decrease is caused by the weaving process; hence, warp and fill yarn interaction during loading contribute to the loss in efficiency.A test fixture was developed to measure the strength of a yarn sample threaded through a series of wires or yarns. This enabled the effect of warp twist and ply on warp strength to be easily and quickly determined under simulated crimp conditions. It was found that yarn strength decreases with decreasing pick spacing in the fixture, as is observed in woven fabrics, and the magnitude of strength decrease varies with yarn twist. optimum fabric strength was predicted to occur at lower warp-twist levels than those established using conventional yarn tests. Comparisons were made between the simulation results and the limited data available for woven structures. A general correlation was obtained for cases where the warp yarns were compressed during fabric construction.

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Section: Mplications Of Simulation Results In Warpmentioning

confidence: 66%

A Technique for Simulating the Stength of Kevlar 29 Yarn in a Woven Configuration

Ericksen¹

1979

Textile Research Journal

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“…It has been shown that increased warp yarn crimp reduces the strength of woven Kevlar structures. 9 The latter result was obtained by altering the pick spacing in woven structures. In the case of a 60 kN webbing, a change in pick spacing from 4 to 6.picks/cm lowered the strength from 70 to 63 kN.…”

Section: Yarn Swellingmentioning

confidence: 99%

“…In the case of a 60 kN webbing, a change in pick spacing from 4 to 6.picks/cm lowered the strength from 70 to 63 kN. 9 By calculating changes in yarn geometry using typical geometric values for the appropriate Kevlar webbing and based on a 4% moisture absorption, 4 it was concluded that fiber swelling was an unlikely mechanism for the observed degradation.…”

Section: Yarn Swellingmentioning

confidence: 99%

Wet Strength of Kevlar 29 Ribbon Parachute Fabrics

Ericksen

Orear

1980

Journal of Aircraft

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The effect of moisture on the strength of Kevlar 29 ribbon parachute fabrics was investigated. Individual yarn samples and various fabrics were soaked in water for periods of 15-60 min. Yarn strength did not change; however, fabric strength was reduced. The reductions ranged 3-13% depending upon the fabric construction. Additional experiments eliminated factors such as the weaving process, yarn swelling, and increased abrasion in the presence of moisture as possible mechanisms. Other tests demonstrated that increased interyarn friction occurs when moisture is present. These results suggest that the moisture-enhanced friction restrains highly loaded filaments from adjusting their position and relieving stress concentrations. Specific construction parameters governing the amount of strength reduction were not defined in this study. However, it is evident that wet strength should be considered in parachute material selection and design.

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“…Of the very few studies on webbings in parachute assemblies [10,11], Ericksen et al [10] evaluated the effect of warp and weft variables on the strength of joints in Kevlar webbings. Onal [11] studied the mechanical properties of notched webbings in cluster sub-munition parachutes.…”

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confidence: 99%

Predicting the Seam Strength of Notched Webbings for Parachute Assemblies Using the Taguchi's Design of Experiment and Artificial Neural Networks

Önal

Zeydan

Korkmaz

2009

Textile Research Journal

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Webbings are used in parachute assemblies as reinforcing units for the strength they provide. The strength of these seams is an important characteristic which has a substantial influence on the mechanical property of the parachute assemblies. It is well established that factors such as fabric width, folding length of joint, seam design and seam type will all have an impact on seam strength. In this work, the effect of these factors on seam strength was studied using both Taguchi's design of experiment (TDOE) as well as an artificial neural network (ANN). In TDOE, two levels were chosen for the factors mentioned above. An L8 design was adopted and an orthogonal array was generated. The contribution of each factor to seam strength was analyzed using analysis of variance (ANOVA) and signal to noise ratio methods. From the analysis it was found that the fabric width, folding length of joint and interaction between the folding length of joint and the seam design affected seam strength significantly. Further, using TDOE, an optimal configuration of levels of factors was found. In order to contrast and compare the results from TDOE, an ANN was also used to predict seam strength using the above mentioned factors as inputs. The prediction from TDOE and ANN methodologies were compared with physical seam strength. It was established from these comparisons, in which the root mean square error was used as an accuracy measure, that the predictions by ANN were better in accuracy than those predicted by TDOE.

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The Effect of Warp and Filling Variables on the Tensile Failure and Joint Strength of Kevlar® 29 Parachute .Webbing

Cited by 6 publications

References 1 publication

A Technique for Simulating the Stength of Kevlar 29 Yarn in a Woven Configuration

A Technique for Simulating the Stength of Kevlar 29 Yarn in a Woven Configuration

Wet Strength of Kevlar 29 Ribbon Parachute Fabrics

Predicting the Seam Strength of Notched Webbings for Parachute Assemblies Using the Taguchi's Design of Experiment and Artificial Neural Networks

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