Assessment of Damage Evolution in Paper Material Based on Acoustic Emission: An Experimental and Statistical Method

Assessments of damage evolution in paper material are essential to understand, predict, and control this material failure, to which has been paid a great attention in the field of pulp and papermaking. However, for many reasons the evaluation of mechanical performance was not the primary concern in the paper industry previously. The most important points lie in lack of experimental means to obtain the complex damage information and hardness of deterministic mechanical formulas in modeling such a heterogeneous material. This chapter introduces an experimental and a statistical method under a multivariate framework to assess the damage evolution of paper material based on acoustic emission (AE). The intrinsic dynamics of material microstructure during damage evolution were captured with high-resolution, high-speed visualization in real time. Certain pivotal AE parameters (such as timing, quantity, and AE amplitude) extracted from the recorded AE signals were used as inputs to establish a multivariate D A including scale and observation vectors. Based on the multivariate D A , information entropy is applied to evaluate damage states quantitatively, and Andrews plot is utilized to cluster damage data with applied stress/strain in different damage stages. Results show that the damage evolution in packaging paper specimen under uniaxial tensile loading mode characters multistage progression, which is evidenced by Andrews plot and optical damage recognition of paper specimen surface topography using scanning electron microscope (SEM) during loading history.