Determination of load-bearing element length in paper using zero/short span tensile testing.Application: This study helps explain the loss of sheet strength that occurs after paper is made from recycled fibers. The tensile strength tensile strength Ratio of the maximum load a material can support without fracture when being stretched to the original area of a cross section of the material. When stresses less than the tensile strength are removed, a material completely or partially returns to its of paper made from previously dried fibers is invariably in·var·i·a·ble adj. Not changing or subject to change; constant. in·var  i·a·bil less than if the fibers were never dried. The cause or causes of this loss of strength is an active area of research. This study develops a new theory for the zero- and short-span tensile strength. It derives art equation using the theory to estimate the average length of load-bearing elements (the distance between serious defects along a fiber length) within a sheet of paper from zero- and short-span tensile strengths. The theory states that the load-bearing element length, [??] is given by [MATHEMATICAL EXPRESSION A group of characters or symbols representing a quantity or an operation. See arithmetic expression. NOT REPRODUCIBLE IN ASCII ASCII or American Standard Code for Information Interchange, a set of codes used to represent letters, numbers, a few symbols, and control characters. Originally designed for teletype operations, it has found wide application in computers. .] where F([[epsilon].sub.frac], 0) is the zero-span strength and dF([[epsilon].sub.frac], G)/dG[|.sub.G = 0] is the gradient gradient In mathematics, a differential operator applied to a three-dimensional vector-valued function to yield a vector whose three components are the partial derivatives of the function with respect to its three variables. The symbol for gradient is ∇. of the zero/short span strength versus span curve evaluated at zero span and G is the span between the jaws. The theory was used to investigate whether the strength reduction when paper is made from previously dried fibers, compared to never dried fibers, is due to the introduction of serious defects, such as kinks, into the fibers during drying. The results suggest that the reduction in the strength of paper made from previously dried fibers, compared to never dried fibers, is not due to the introduction of serious defects during drying. Batchelor is with the Australian Pulp and Paper Institute, Department of Chemical Engineering P.O. Box 36,, Monash University Facilities in are diverse and vary in services offered. Information on residential sevices at Monash University, including on-campus (MRS managed) and off-campus, can be found at [2] Student organisations , 3800 Victoria, Australia. Email Batchelor at warren.batchelor@eng.monash.edu.au. |
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