CAJ | 학술논문

为研究散料属性与锥仓结构对散料与锥仓之间接触状态的影响，建立了自由开接触、滑移闭接触、黏着闭接触等状态的接触条件与数学求解模型；以葵花籽、玉米、煤粉、圆砾石、小麦为实例，进行了散料在不同倾角锥仓中的静压接触状态有限元分析，给出了5种散料在倾角分别为20°、33.7°、45°的锥仓中的接触状态。结果显示：散料堆积密度、弹性模量、泊松比、膨胀角、内摩擦角、内聚力等属性对散料在锥仓中的接触状态影响程度不同，其中膨胀角和内聚力有较大影响，膨胀角很小时，可能会有开接触状态，内聚力越大，则黏着接触区越小；锥仓由深向浅过渡时，开接触区域会消失，滑移接触区会变小，黏着接触区会增大。当散料黏着接触区增加时，不利于锥仓卸料；滑移接触区增加则对锥仓表面摩擦损伤大。通过散料在锥仓中的接触状态研究可从力学特性上评价锥仓设计与储料效率。
위연구산료속성여추창결구대산료여추창지간접촉상태적영향，건립료자유개접촉、활이폐접촉、점착폐접촉등상태적접촉조건여수학구해모형；이규화자、옥미、매분、원력석、소맥위실례，진행료산료재불동경각추창중적정압접촉상태유한원분석，급출료5충산료재경각분별위20°、33.7°、45°적추창중적접촉상태。결과현시：산료퇴적밀도、탄성모량、박송비、팽창각、내마찰각、내취력등속성대산료재추창중적접촉상태영향정도불동，기중팽창각화내취력유교대영향，팽창각흔소시，가능회유개접촉상태，내취력월대，칙점착접촉구월소；추창유심향천과도시，개접촉구역회소실，활이접촉구회변소，점착접촉구회증대。당산료점착접촉구증가시，불리우추창사료；활이접촉구증가칙대추창표면마찰손상대。통과산료재추창중적접촉상태연구가종역학특성상평개추창설계여저료효솔。
Finite element models, which employ the Drucker-Prager yield criterion, have been developed to simulate the static contact statuses between conical silos and granular materials in 3 forms:the near contact, the sliding contact and the sticking contact. Contact conditions are established when 2 separated surfaces touch at normal direction while maintaining tangential relative movement. In general physical meaning, the surfaces in contact status have the following characteristics: 1) No penetration between each other;2) The normal pressure and the tangent friction force may be transferred during contact;3) Generally the normal pulling force cannot be transferred when surface separation occurs. Due to the symmetric property of conical structures, simplified two-dimensional contacting simulations are carried out in this paper, nonlinear finite element software ANSYS is used and the contacting surfaces between granular materials and conical silos are defined with rigid-to-flexible surface-to-surface contact pair. The target surfaces of conical silos are modeled with TARGE169 element and the contact surfaces of granular materials are modeled with CONTA171 element. During finite element analysis, conical silos and granular materials are meshed with two-dimensional solid element, PLANE42. The static contact statuses are investigated with conical silos containing different granular materials. The silo geometries vary at a dip angle of 20°, 33.7° and 45°. Sunflower seeds, corn, coal, rounded gravel and wheat are selected as the granular materials. Results show that the mechanical properties of granular materials (including bulk density, elastic modulus, Poisson's ratio, dilation angle, internal friction angle, cohesion) and silo designs (especially dip angle) have significant effects on the contact statuses at the interface between conical silos and granular materials:1) For various granular material, 3 contact statuses, i.e. the form of near contact, sliding contact and sticking contact, can be found between granular materials and conical silo walls;2) The contact statuses between conical silos and granular materials do not depend on (or not mainly depend on) any mechanical property of granular materials. The contact statuses are a combined effect of all mechanical properties of granular materials. Those granular materials with very small dilation angle may have the near contact statuses. Those granular materials with higher cohesive force usually present a smaller sticking contact area, and those granular materials with higher elastic modulus and bulk density usually present a larger sticking contact area than those with opposite material properties;3) With the decreasing of conical silo depth, the near contact area disappears, the sliding contact area decreases and the sticking contact area increases. 4) Under the sliding contact status, the friction energy dissipation is mainly due to the relative motion between contact surfaces. Under the sticking contact status, the friction energy dissipation is mainly due to the elastic deformation because of the contact. The greater the sticking contact area, the more difficultly the silo discharges. The greater the sliding contact area, the more seriously the silo internal surfaces could be damaged. Since larger sticking/sliding contact area inevitably causes unloading difficulties or friction damage, contact statuses between granular materials and conical silos should be optimized in the silos design in order to boost storage efficiency.