Granular Material And Flow Pipeline Of Fluid-structure Interaction Dynamics Research

Concrete granular material is a complex mixture that is widely used in modern construction.The microscopic mechanical properties of granular materials rise rapidly with the development of discrete element technologies.The importance of the rheological problems related research in the field of concrete is also becoming manifest.However,building of microscopic constitutive models is still lack of a high feasibility platform,their related direction research is also due to the lack of a platform model facing many difficulties and challenges.Discrete Element technology has played a role as a bridge in the study of granular material in the macroscopic and microscopic characteristic,which provides a medium for revealing the nature of the granular material;In addition,granular material flow in pipes conveying fluid can cause friction and vibration and energy dissipation,which has a negative effect on the construction,and its widespread use,the negative effects resulting impact on national construction projects become more prominent.Essential attribute of the above research has guiding significance for the actual construction,and in-depth study of the field theory can provide references of the innovative direction.Two key issues surrounding the above-mentioned problems to be solved,the paper conducted the following research work about rheological properties of granular materials and coupling characteristics and delivery systems research work carried out as follows:Taking concrete as the study background and granular material as the research object,to build custom contact model for description of wet particles and combined with Microsoft Visual Studio 2005 C ++ platform to get a dynamic link library(DLL)file of the model;The dynamic link library file provides an important theoretical and contact model support,and for the refinement of research related to the wet granules model provides research ideas with a reference value.Applications PFC2D software,reverse simulation test to determine parameters,to obtain a granular material slump parameters,L-shape box self-compacting parameters,V-shape box flow characteristic parameters for reference;Further selected granular material flow pipe bending behavior research for practical engineering scheme,running by loading the corresponding dynamic link library(DLL)file,analyzing granular materials bend flow behavior,change the relationship between displacement and force chains,obtained particulate material flow pattern,indicating that the complexity of non-continuity discrete particles is root causes that changing of its state motion mutation,which proves the effectiveness of custom contact model.Fluid-structure coupling mechanics model of conveying pipeline flow process is built,the not limited fixed initial-boundary value problem of fluid-structure interaction nonlinear partial differential vibration equation is obtained;To simplify the calculation equation solving,expanding the scope of use of the vibration differential equations,using dimensionless ideas to make the above equations dimensionless,thus providing a mechanical model of reference for the fluid-structure interaction equations similar pipes conveying fluid.Using the finite difference method transform partial differential equations into a nonlinear difference equations,and based on the principle of catch-up method,the algorithm for higher order nonlinear partial differential equations is proposed,and the specific conveying fluid pipeline fluid-structure interaction equation is programmed.Nonlinear difference equations partial differential equation is converted by using the finite difference method.Through the example analysis of the influence of different flow rate on the system natural frequency,and determine the critical speed,provides scientific basis for the practical engineering application.In conclusion,based on the discrete element contact model as the theoretical guidance,micro mechanical parameters of concrete material particles as the research object,simulating granular materials rheological test,reveals that the dynamic characteristics of granular material micro and macro fundamental mechanism;At the same time taking pipeline system as the research object,taking flow pipeline multi-scale fluid-structure interaction vibration problem as the research key,flow pipeline fluid-structure interaction dynamics model is established.The results of the flow pipeline system has important guiding significance to the reasonable monitor and vibration control,at the same time,the stability problem of flow pipeline system has important reference value.