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Determination of large deformation and fracture behaviour of starch gels from conventional and wire cutting experiments

“…Manufacturing processes involving large deformation, fracture or separation of the material, e.g. cutting, slicing etc, are widely used in the food industry [1][2][3][4]. Fracture of food also occurs during mastication when the structure of food is broken down and the flavour and aroma are released [5].…”

“…Large deformation behaviour of foods is commonly obtained via the uniaxial compression experiment [6] while fracture behaviour can be investigated by the single edgenotched bend (SENB) test [1]. However, the use of the SENB test for food can be difficult as most food exhibits a high degree of rate dependence, non-linearity and low stiffness.…”

“…However, the use of the SENB test for food can be difficult as most food exhibits a high degree of rate dependence, non-linearity and low stiffness. For these reasons, a simpler alternative test based on wire cutting, which involves pushing wires with various diameters into a specimen to a steady state cutting stage, has been proposed for measuring the fracture toughness of food [1,5]. A typical force-displacement trace for a wire cutting test is shown in Fig.…”

“…At some point during the indentation, the material starts to fracture and a steady state cutting phase proceeds. In the wire cutting process, fracture, large deformation and surface friction occur simultaneously [1,5]. It has been stated by [7] that the force F required for cutting is proportional to the wire diameter (d) and that there is a constant component arising from G c , the fracture toughness.…”

“…The proportionality factor with the diameter was then determined from the deformation energy and the friction. A linear equation between the cutting force and wire diameter was developed by [1] and has the form,…”