Accession Number:

ADA031396

Title:

Response of Polymers to Tensile Impact. 3. The Integral-Equation, Successive-Substitution Method Applied to Non-Linear Materials Having Time- Dependence (Creep, Relaxation)

Descriptive Note:

Technical rept.

Corporate Author:

ARMY NATICK RESEARCH AND DEVELOPMENT CENTER MA

Report Date:

1976-01-01

Pagination or Media Count:

68.0

Abstract:

A better understanding is required of tensile-impact strains in military components such as body armor and parachute straps. A solution for the propagation of strain waves in elastic materials was extended to materials exhibiting creep and relaxation. The basic integral-equation, successive- substitution solution developed in two previous reports was extended using a model with two springs in series and a dashpot in parallel with one of them. With appropriate values, the model conformed adequately to experimental tensile- impact data on a 50 cm length of Nylon yarn. For this short specimen, wave reflections confused the experimental data and there was a lack of uniqueness in the computed results. Different choices of model parameters represented the data equally well. Hence impact experiments were made on 400 cm specimens of Nylon yarn in which reflections would not be observed. We were unable to represent these experiments with the model. The experimental data showed that the Nylon contracted after the initial strain pulse had elongated it. 4 strains fell to 3 during a single experiment. Contraction of the material had not been expected and deserves further investigation. Methods of choosing the parameters of the model are presented in an appendix.

Subject Categories:

  • Textiles
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE