The Combined Effects of Moisture and Temperature on the Mechanical Response of Paper

To model advanced 3-D forming strategies for paper materials, the effects of environmental conditions on the mechanical behavior must be quantitatively and qualitatively understood. A tensile test method has been created, verified, and implemented to test paper at various moisture content and temperature levels. Testing results for one type of paper for moisture contents from 6.9 to 13.8 percent and temperatures from 23 to 168 degrees Celsius are presented and discussed. Coupled moisture and temperature effects have been discovered for maximum stress. Uncoupled effects have been discovered for elastic modulus, tangent modulus, hardening modulus, strain at break, tensile energy absorption (TEA), and approximate plastic strain. A hyperbolic tangent function is also utilized which captures the entire one-dimensional stress-strain response of paper. The effects of moisture and temperature on the three coefficients in the hyperbolic tangent function may be assumed to be uncoupled, which may simplify the development of moistureand temperature-dependent constitutive models. All parameters were affected by both moisture and temperature with the exception of TEA, which was found to only be significantly dependent on temperature. E. Linvill KTH Royal Institute of Technology Department of Solid Mechanics SE 100 44 Stockholm Tel.: +46-76-5946093 E-mail: [email protected] S. Östlund KTH Royal Institute of Technology Department of Solid Mechanics SE 100 44 Stockholm Tel.: +46-8-7907542 E-mail: [email protected] 2 Eric Linvill, Sören Östlund