BRUISING AND ENERGY DISSIPATION IN APPLES
BRUISING AND ENERGY DISSIPATION IN APPLES
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DOI：
10.1111/j.1745-4603.1977.tb01149.x
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发表时间：
1977-06
影响因子：
3.2
通讯作者：
J. Holt;D. Schoorl
中科院分区：
文献类型：
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作者：
J. Holt;D. Schoorl
无论是冲击还是缓慢压缩，青草苹果的伤痕体积与所吸收的能量都有很强的相关性。苹果组织更容易被缓慢压缩而不是撞击擦伤。对于相同的能量，在缓慢压缩下，瘀伤体积大约高出40%。苹果果肉的硬度(力/挠度)与挫伤体积之间没有相关性。基于弹性理论的失效理论不太可能被证明对预测瘀伤的程度有用。本文未对弹性理论在擦伤起因中的应用进行研究。建立了一个简单的模型来解释苹果在压缩下的行为。苹果组织被比作有序排列的充满液体的球形细胞，细胞周围有粘弹性薄膜和充满空气的间质。假定在初始压缩时，单元在类似于弹性球体的应力分布下变形成椭球体。进一步的压缩将导致细胞壁破裂，即高剪应力区域的细胞破裂。细胞的变形和破裂解释了能量耗散机制。这项工作表明，压缩过程中吸收的能量是擦伤的一个很好的预测指标，因此是评估搬运和包装系统的有用参数。
A strong correlation was obtained between bruise volume and energy absorbed for both impact and slow compression of Granny Smith apples. Apple tissue was more easily bruised by slow compression than by impact. For the same amount of energy, bruise volumes were approximately 40% higher under slow compression. There was no correlation between the stiffness (force/deflection) of apple flesh and bruise volume. It is unlikely that the theories of failure based on the theory of elasticity will prove useful in predicting the extent of bruising. The application of elastic theory to bruise initiation was not studied in this paper. A simple model was formulated to explain the behaviour of apples under compression. Apple tissue was likened to an orderly arrangement of liquid-filled, spherical cells bounded by viscoelastic membranes with air-filled interstitials. It is postulated that on initial compression the cells are deformed into ellipsoids under a stress distribution similar to that found in an elastic sphere. Further compression would then result in cell wall fracture, i.e., cell bursting in regions of high shearing stress. Distortion and bursting of cells explains the energy dissipative mechanism. The work showed that energy absorbed during compression is a good predictor of bruising and is, thus, a useful parameter in evaluating handling and packing systems.