TY - GEN
T1 - A constitutive model for materials with transversely isotropic strain locking microstructures
AU - Payne, Nicholas
AU - Pochiraju, Kishore
N1 - Publisher Copyright:
© ASC 2020.
PY - 2020
Y1 - 2020
N2 - Strain locking materials have a limit to the degree to which they can be stretched along one or more axes. The limiting strain behavior is due to stiff microstructure components that reorient along the direction of the applied load as stretch increases. Both natural and manmade materials can exhibit such a response when initially wavy fibers or other corrugated structures gradually straighten and limit the extensibility of the material. Two new constitutive models are developed which describe materials with strain locking structures that are oriented along a particular axis. The models assume the microstructure is composed of linear elastic material with embedded zigzag shaped, series of structures oriented along a preferential axis which produce the locking behavior. The response is governed by a strain energy density function which is partitioned into separate portions that represent the stored energy within the fibers and the matrix respectively. A new, nonlinear form for the strain energy density function of strain locking fibers is derived based on the change in angle of the fiber’s vertices. Examples of the mechanical response are demonstrated for a matrix material defined by a linear elastic model. The model parameters are fit to tensile stress versus strain data generated from Finite Element Analysis of a strain locking composite RVE as well as experimental data from a strain locking composite thin-film material. Correlation with the experimental data shows that the proposed constitutive model accurately fits the initial tangent modulus and ultimate strain locking limit well.
AB - Strain locking materials have a limit to the degree to which they can be stretched along one or more axes. The limiting strain behavior is due to stiff microstructure components that reorient along the direction of the applied load as stretch increases. Both natural and manmade materials can exhibit such a response when initially wavy fibers or other corrugated structures gradually straighten and limit the extensibility of the material. Two new constitutive models are developed which describe materials with strain locking structures that are oriented along a particular axis. The models assume the microstructure is composed of linear elastic material with embedded zigzag shaped, series of structures oriented along a preferential axis which produce the locking behavior. The response is governed by a strain energy density function which is partitioned into separate portions that represent the stored energy within the fibers and the matrix respectively. A new, nonlinear form for the strain energy density function of strain locking fibers is derived based on the change in angle of the fiber’s vertices. Examples of the mechanical response are demonstrated for a matrix material defined by a linear elastic model. The model parameters are fit to tensile stress versus strain data generated from Finite Element Analysis of a strain locking composite RVE as well as experimental data from a strain locking composite thin-film material. Correlation with the experimental data shows that the proposed constitutive model accurately fits the initial tangent modulus and ultimate strain locking limit well.
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M3 - Conference contribution
AN - SCOPUS:85097305364
T3 - Proceedings of the American Society for Composites - 35th Technical Conference, ASC 2020
SP - 238
EP - 267
BT - Proceedings of the American Society for Composites - 35th Technical Conference, ASC 2020
A2 - Pochiraju, Kishore
A2 - Gupta, Nikhil
T2 - 35th Annual American Society for Composites Technical Conference, ASC 2020
Y2 - 14 September 2020 through 17 September 2020
ER -