RHEOLOGICAL BEHAVIOUR OF BUTTER AT SMALL DEFORMATIONS
RHEOLOGICAL BEHAVIOUR OF BUTTER AT SMALL DEFORMATIONS
复制标题
小变形时黄油的流变行为
DOI：
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
K.
中科院分区：
文献类型：
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作者：
H. Rohm;K.
通过剪切应力松弛实验和5-20℃压缩蠕变实验，对11个传统生产的黄油样品在不同几何尺寸和压缩速率下的润滑和非润滑单轴压缩下的大变形流变特性进行了评价。在无润滑条件下，使圆柱体样品变形所需的压缩力比在润滑情况下要高。对无润滑应力-应变曲线的形状变化进行了修正，在低压缩比至应力极大值或屈服时，结果与润滑实验吻合较好。由于摩擦力在高变形率下相对较小，因此在无润滑条件下获得较低的应力。高径比越大的试件，应力最大值越明显。计算了非脆性软样品的双向拉伸粘度ηBE。在粘度与应变率的对数曲线中，典型的斜率约为-1。当应变约为0.01时，蠕变柔量取决于压缩应力。平均恢复顺应性与初始瞬时顺应性的比值在0.31~0.59之间，并随着样品温度的升高而增大。由蠕变压缩计算的ηBE与由静态压缩实验得到的ηBE吻合较好。在可比应变下，用近似方法将蠕变柔量换算为应力松弛模数与实验结果吻合较好。
Eleven traditionally produced butter samples were evaluated for rheological properties at large deformations by lubricated and nonlubricated uniaxial compression with varying sample geometries and compression rates, by stress relaxation in shear and creep experiments in compression at 5–20C each. Compression forces required to deform cylindrical samples in nonlubricated conditions were higher than in lubricated cases. Correction of shape changes in nonlubricated stress-strain curves resulted in good agreement with lubricated experiments at low compression rates up to stress maxima or yielding. As frictional forces were relatively smaller at high deformation rates, lower stresses were obtained in nonlubricated conditions. Samples with higher height/diameter ratios showed more pronounced stress maxima. A biaxial extensional viscosity, ηbe, was computed for nonbrittle, soft samples. Typical slopes in logarithmic plots of viscosity against strain rate were approximately -1. At strains of about 0.01 creep compliance depended on compression stress. The average ratios of recovered to initial instantaneous compliance were between 0.31 and 0.59, and increased with sample temperature. A calculated ηBE from creep compression showed fair agreement with ηBE from static compression experiments. At comparable strains, a conversion of creep compliance to the stress relaxation modulus by an approximate method showed a good fit of experimental results.