Structural Failure in Selected Raw Fruits and Vegetables1

Abstract

A torsion test was developed for studying the structural failure of selected raw fruits and vegetables. Apple, melon and raw potato flesh were tested at a shear strain rate of approximately 0.26s‐1 in torsion and uniaxial compression. Low strain modulus values were determined in addition to shear stresses and normal strains at failure. Results corroborated the maximum normal strain failure criterion proposed by Segerlind and Dal Fabbro (1978) for apples and suggested its application to potatoes and melons if true strains are used rather than engineering strains. The maximum shear stress theory also seemed to be a possible failure criterion for potatoes. Results comparing compressible and incompressible materials suggest that bulk strain affects the shear stress at failure. The observed failure planes supported the quantitative results for stresses at failure. Scanning electron micrographs indicated that the cellular failure occurred in the cell wall, regardless of whether it was due to tension, Varying specimen lengths or diameters had negligible effects on the uniaxial compression modulus but did affect the shear stress at failure in a manner yet to be satisfactorily explained.

Firmness evaluation of melon using its vibration characteristic and finite element analysis

“…All estimated dynamic MOEs were comparable with reference data on melons (Chen et al, 1996). It was reported that the dynamic MOEs were also about 2 to 10 times static MOE of melons (Deihl et al, 1979). The MOE of FE model was tuned such that the first bending mode frequency matched experimental frequency (Cherng, 2000).…”

Differences in the Structural Response of ‘Granny‐smith’ Apples Under Mechanical Impact and Compression

“…The rupture of the cell wall is not indispensable, at least in small bruises, for the reaction to succeed. This finding contradicts Diehl et al (1979) andPitt (1982) postulations that cell wall rupture is necessary.…”

“…In recent years, several studies (Chen et al 1986;Diehl et al 1979;Garcia 1988;Holt and Schoorl 1977a;Topping and Luton 1986) have been earned out to investigate the appearance and development of fruit bruises. The study of bruises incurred by compression and impact damage in fruit harvesting, handling, packaging and transport operations is necessary from the point of view of market quality in fresh fruits.…”

Modelling the area expansion ratio on uniaxial compression of cylindrical potato samples

“…Average values of AF r /A 0 obtained in lubricated and non-lubricated friction conditions (1.4723 and 1.3964, respectively) are difficult to compare with the few data existing in the literature, corresponding to products of distinct nature (Culioli & Sherman, 1976;Olkku & Sherman, 1979) or to tests carried out under different experimental conditions. In potato compression tests without lubrication, Diehl, Hamann, and Whitfields (1979) pointed out an increase of the sample diameter of the 15% equivalent to an AF r /A 0 value of 1.3225, while Canet and Sherman (1988) obtained the lowest value (1.2807).…”