上海交通大学：《食品物性学 Physical Properties of Foods》教学资源（中文PPT课件）06 散粒体食品的力学特性

6散粒体食品的力学特性 國

Sources of Cohesion (Binding Mechanisms) Solids Bridges Attraction Forces -Mineral bridges -van der Waal's -Chemical reaction -Electrostatics -Partial melting -Magnetic -Binder hardening Interfacial forces -Crystallization -Liquid bridges -Sublimation -Capillary forces Interlocking forces

农业物料的摩擦力 物料压力 物料湿度 颗粒表面状态（物理、化学性质） 接触时间 物料温度

摩擦性 休止角-注入法 Grain Bin ll Grain Surface at Filing Grain Surface at Emptying ○X Bin Floc -Angle of bin wall from horizontal -Filing angle of repose.usually less than emptying angle of repose -Emptying angle of repose.usually taken os the internal angle of frictior Flgure 1:Angle of Response

摩擦性 休止角-排出法 600 20 0 黑

What about angle of repose? Pile of bulk solids U C L

 Pile of bulk solids  

颗粒度 水分 The Angle of Repose 35 fine sand dry s sand 40 coarse sand moist sand angular 45 pebbles 35883ma water saturated windward leeward sand

形状与粒度

内摩擦角 WxA Bracket Cover Ring SXA Bulk Solid Shear plane

Ring Cover W x A S x A Bracket BBuulklkSSoolildid Shear plane

内摩擦角 F=fF+FA IN

Fs  f iFN  Fc A