Hollow rod-shaped flexible body dynamic characteristic modeling and simulation method

Abstract

The invention discloses a modeling and simulation method for dynamic characteristics of a hollow rod-shaped flexible body. the rod-shaped discrete element model is formed by connecting spherical particles on a straight line through an elastic virtual key; each virtual key is an elastic hollow cylinder; the virtual keys are connected to the adjacent virtual keys through the spherical particles, theouter diameters of the spherical particles are equal to the outer diameter D of the simulated object, the lengths lb of the virtual keys are equal to the distance between the two bonded spherical particles, the outer diameters of the virtual keys are equal to the outer diameter D of the simulated object, and the inner diameters of the virtual keys are equal to the inner diameter d of the simulated object. Under the action of an external force, an external force is applied, the relative movement of the spherical particles causes the deformation of the virtual key; According to the dynamic model of the flexible body, the bonding force and the torque on the spherical particles can be obtained through increment and accumulation of each time step, and the acting force between the hollow rods or the acting force between the hollow rods and other objects can be obtained through the Hertz-Mindlin collision theory.

Description

technical field [0001] The invention relates to dynamics and kinematics analysis of crop stalks, which is a modeling and simulation method for the dynamic characteristics of a hollow rod-shaped flexible body, and is especially suitable for analyzing the interaction between crop stalks and machinery in the process of agricultural machinery operation and agricultural machinery devices structural optimization. Background technique [0002] With the improvement of the level of agricultural mechanization, the requirements for the performance of agricultural machinery are gradually increasing. For example, agricultural harvesting machinery can separate more than 100 tons of grain and stalk mixture per hour, and the acceptable loss of each sub-process is generally less than 1%. Therefore, it is of great significance to study the mechanical properties of crop stalks during the operation of agricultural machinery for the development of agricultural machinery with stable performance ...

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Problems solved by technology

Document 1 "Study on the Buckling Behavior of Plant Stalks" (Shanghai Jiaotong University, 2009) and Document 2 "Research on Discrete Element Modeling Method for Mechanical Properties of Corn Stalks" (Northwest A&F University, 2017) respectively use finite element and discrete element methods , studied the mechanical properties of crop stalks under loads such as compression, tension and torsion, but the models proposed in Document 1 and Document 2 cannot be applied to the simulation of dynamic kinematics characteristics of crop stalks during agricultural machinery operations

Document 3 "Simulation of grain–straw separation by Discrete Element Modeling with bendable straw particles" (Computers and Electronics in Agriculture 101 (2014) 24–33.) proposes a simulation method for flexible crop stems, but the stems described in the article The stalk model is obtained through rigid bond connection, and the rigid bond will not bend. The bending of the stalk is realized by simulating the spring force at the connection between the bond and the bond. The accuracy of the simulation model is limited by the model mechanism

At present, the commercial software EDEM provides the Hertz–Mindlin with bonding model, which can be used for modeling and simulation of flexible crop stems, but only solid rod-shaped models can be constructed in EDEM

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