| Resin mineral composites have gradually begun to replace cast steel and cast iron in the preparation of mechanical basic components due to their excellent dynamic properties.However,on the one hand,due to the influence of its preparation and molding methods and its own structural characteristics,it is easy to form micropores and microcracks in the early stage of curing,which reduces the mechanical properties of the component;On the other hand,und er the influence of dynamic loads during mechanical operation,new cracks initiate and expand in the foundation during normal service,ultimately leading to damage and failure of the foundation.Recently,with the development of "smart materials",the post damage repair of resin mineral composite components has attrac ted much attention,mimicking the self-healing characteristics of organisms after damage.However,the introduction of microcapsules to achieve self-healing will damage the mechanical properties of resin mineral composite materials.The research on how to balance selfhealing performance and mechanical properties and determine the amount of microcapsules is still in its infancy,and there is no systematic theory and method formed.Therefore,the research on the optimal performance of metal containing microcapsules self-healing resin mineral composite materials is crucial.Based on this background,this paper studies the optimal performance of metal containing microcapsules self-healing resin mineral composites.The main research work is as follows:(1)Aiming at the unclear failure situation of metal microcapsules,an analytical simulation method based on molecular dynamics and extended finite element method was proposed.The damage evolution process of the matrix interface of metal microcapsule/resin mineral composite material was simulated using molecular dynamics method.The damage evolution process can be divided into three processes:initial deformation,local damage,and overall damage.The i nterfacial mechanical properties were obtained through the simu lation results.The elastic modulus of the capsule wall/substrate interface was 6.458 GPa,and the strength limit was 62 MPa.Based on this,the fracture behavior of metal microcapsules was sim ulated using extended finite element method.Through analysis o f the simulation results,it was found that metal microcapsules only damaged after the occurrence of matrix cracks,but the damage time was earlier than the arrival of matrix cracks at the meta l microcapsules.This provides a feasibility analysis of adding metal microcapsules to achieve self-healing functions and the mechanical properties of the capsule wall/resin mineral composite matrix interface of metal microcapsules for subsequent research.(2)Aiming at the lack of research on the impact of traditiona l microcapsule models on the core loss characteristics of microcapsules,a dedicated microcapsule mechanical model including the impact of core content was proposed.Using the improved Reissner theory and Tatara theory,the mechanical models of the capsule wall and core were established,and the mass ratio of the capsule core was used to calculate the amount of core loss that was ignored in traditional research.This revealed the relationship between core deformation and compression,and developed a universal and effective mechanical model with microcapsule characteristics.Based on this mechanical model,the mechanical response results of various types of microcapsules were predicted,and satisfactory prediction results were obtained.The elastic modulus of metal microcapsules was 4.49 GPa,and the Poisson’s ratio was0.24.On the other hand,in order to understand the mechanical contribution of each part of the microcapsule,a set of orthogonal tests were designed based on this mechanical model.The results were analyzed using multiple linear regression methods,and the degree of influence of various parameters of the microcapsule on the mechanical response results was obtained.It was found that when the deformation amount was large,the overall mechanical response of the microcapsule was determined by the size and core of the microcapsule,and the main role of the capsule wall was to wrap and protect the core,and determine the results of the mechanical response when the deformation is small.The role of th e core and wall in the structure of microcapsules was analyzed mathematically,and the overall mechanical properties of metal microcapsules were provided for subsequent research.(3)Aiming at the problem that the repair rate and elastic modulus of self-healing resin mineral composites containing metal microcapsules have contradictory characteristics,which leads to the difficulty in determining the dosage of microcapsules,a method for optimizi ng the design of the dosage of microcapsules is proposed.The cohesive force element was used to overcome the problem of neglecting the influence of adhesive interface in conventional analysis.Based on the extended finite element method,the damage evolut ion process of the mesostructure of circular microcapsule self-healing resin mineral composite was simulated,and its crack distribution was obtained,revealing its damage mechanism and crack distribution rules.The functional relationship between the amou nt of microcapsules and the repair rate was further analyzed th rough crack propagation.A mathematical relationship model between the amount of microcapsules and the elastic modulus of materials was derived using the Mori-Tanaka method,which was improved by the step-by-step inclusion method.Based on these two relati onal models,a multiobjective optimization algorithm based on LINMAP decision-making was used to optimize the dosage of microcapsules,and the optimal dosage of microcapsules was obtained.The optimization results show that the optimal microcapsule conten t for a resin mineral composite machine tool is 1.68%,at which time the elastic modulus of the material is 30.92 GPa,Poisson’s ratio is 0.25,and the repair rate is 25.38%. |
PDF Full Text Request