本文選題：顆粒材料 + 離散元方法��； 參考：《大連理工大學(xué)》2015年碩士論文

【摘要】：顆粒物質(zhì)是自然界中存在最多的物質(zhì)之一。它與人們的生活密切相關(guān),并在工農(nóng)業(yè)、航空航天、交通運(yùn)輸、建筑工程、自然災(zāi)害等各領(lǐng)域均得到良好地應(yīng)用。顆粒物質(zhì)不僅兼具流體與固體的性質(zhì),通常還會(huì)表現(xiàn)出更加復(fù)雜的力學(xué)性質(zhì),其中之一就是快速耗能特性。當(dāng)顆粒物質(zhì)承受外載荷作用時(shí),會(huì)產(chǎn)生強(qiáng)烈的擠壓和碰撞,使系統(tǒng)能量得到快速有效地衰減,從而對(duì)外載荷起到良好的緩沖作用。因此,顆粒物質(zhì)通常被用來(lái)作為作減振吸能的優(yōu)選材料。針對(duì)顆粒物質(zhì)的緩沖特性,本文采用離散元方法,結(jié)合Hertz接觸理論,建立了沖擊物對(duì)顆粒材料的沖擊模型,旨在揭示顆粒材料緩沖特性的內(nèi)在作用機(jī)理以及其主要影響因素,并在此基礎(chǔ)上進(jìn)行深入的研究。本文工作將會(huì)對(duì)減振技術(shù)的提升具有指導(dǎo)意義,為顆粒材料的工程應(yīng)用提供理論基礎(chǔ)。首先,本文采用球形顆粒單元建立了顆粒材料的沖擊模型。分析沖擊物在不同顆粒層厚度下的運(yùn)動(dòng)規(guī)律及底板的受力特性,探討了顆粒層厚度、表面摩擦系數(shù)以及初始排列密集度對(duì)顆粒材料緩沖性的影響,并從力鏈結(jié)構(gòu)和能量變化的角度分析其內(nèi)在作用機(jī)理,揭示了力鏈結(jié)構(gòu)、能量耗散與顆粒物質(zhì)緩沖性之間的關(guān)系。其次,文章分別建立了散體顆粒材料和粘結(jié)顆粒在隨機(jī)排列和規(guī)則排列方式下的沖擊模型,對(duì)沖擊物和底板進(jìn)行動(dòng)力分析。研究了粘結(jié)強(qiáng)度對(duì)顆粒材料緩沖特性的影響和底板分布力的變化規(guī)律,并從細(xì)觀角度展現(xiàn)了點(diǎn)載荷向分布載荷轉(zhuǎn)化的過(guò)程。揭示了顆粒系統(tǒng)的緩沖特性與顆粒粘結(jié)強(qiáng)度、顆粒自由滑移度之間的關(guān)系,同時(shí)說(shuō)明了排列方式對(duì)顆粒力鏈結(jié)構(gòu)的決定性作用。最后,結(jié)合真實(shí)的沖擊環(huán)境,介紹了沖擊響應(yīng)譜理論及其時(shí)域合成算法,選用合適的基本波形將沖擊響應(yīng)譜合成時(shí)域激勵(lì)信號(hào)。將時(shí)域信號(hào)作為激勵(lì)條件,采用離散元方法建立了粘結(jié)顆粒材料在時(shí)域激勵(lì)作用下的沖擊模型,計(jì)算不同排列方式下沖擊物及底板的力學(xué)響應(yīng),并分析彈性模量對(duì)其緩沖特性的影響。結(jié)果表明,粘結(jié)顆粒材料能夠通過(guò)降低振動(dòng)頻率和振幅從而對(duì)時(shí)域沖擊激勵(lì)起到衰減作用,并且衰減程度受排列方式和彈性模量的影響。
[Abstract]:It is closely related to people's life and has been well applied in the fields of industry and agriculture, aerospace, transportation, construction engineering, natural disasters and so on.Granular matter not only has the properties of fluid and solid, but also shows more complex mechanical properties, one of which is fast energy dissipation.When the particle material is subjected to external load, it will produce strong squeezing and collision, so that the energy of the system will be rapidly and effectively attenuated, thus the external load will play a good role in buffering.Therefore, particulate matter is usually used as an optimal material for vibration and energy absorption.Aiming at the buffer characteristics of granular materials, the impact model of impact materials on granular materials is established by using discrete element method and Hertz contact theory. The purpose of this paper is to reveal the internal mechanism of buffer properties of granular materials and its main influencing factors.And on the basis of this in-depth study.The work in this paper will be of guiding significance to the improvement of vibration absorption technology and provide a theoretical basis for the engineering application of granular materials.Firstly, the impact model of granular material is established by using spherical particle element.The effects of particle thickness, surface friction coefficient and initial arrangement density on the cushioning properties of granular material are discussed by analyzing the motion law of impact material under different particle layer thickness and the mechanical characteristics of the bottom plate, and the effects of particle thickness, surface friction coefficient and initial arrangement density on the buffer properties of granular material are discussed.From the point of view of force chain structure and energy change, the internal action mechanism is analyzed, and the relationship between force chain structure, energy dissipation and buffer property of granular material is revealed.Secondly, the impact models of granular materials and bonded particles in random arrangement and regular arrangement are established, and the dynamic analysis of impact material and bottom plate is carried out.The influence of bond strength on the buffer characteristics of granular materials and the variation of the distribution force of the bottom plate are studied, and the process of transformation from point load to distributed load is shown from the view of meso.The relationship between the buffer characteristics of the particle system and the particle bond strength and the free slip degree of the particles is revealed, and the decisive effect of the arrangement mode on the structure of the particle force chain is also explained.Finally, combined with the real impact environment, the theory of impulse response spectrum and its time-domain synthesis algorithm are introduced.The time domain signal is taken as the excitation condition and the discrete element method is used to establish the impact model of the bonded particle material under the time domain excitation. The mechanical responses of the impact material and the bottom plate under different arrangement are calculated.The influence of elastic modulus on its buffer property is analyzed.The results show that the bonded granular material can attenuate the shock excitation in time domain by reducing the vibration frequency and amplitude, and the attenuation degree is affected by the arrangement mode and elastic modulus.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.4

【參考文獻(xiàn)】

相關(guān)期刊論文 前5條

1 陳小慧;閆兵;李華超;;沖擊響應(yīng)譜時(shí)域合成算法研究[J];包裝工程;2007年02期

2 趙金鳳;嚴(yán)穎;季順迎;;基于離散元模型的土石混合體直剪試驗(yàn)分析[J];固體力學(xué)學(xué)報(bào);2014年02期

3 馬愛(ài)軍,朱惠芳,黃曉慧,曾固;航天器爆炸沖擊環(huán)境模擬裝置述評(píng)[J];航天醫(yī)學(xué)與醫(yī)學(xué)工程;1998年05期

4 季順迎;李春花;劉煜;;海冰離散元模型的研究回顧及展望[J];極地研究;2012年04期

5 何克晶;張金成;周曉強(qiáng);;運(yùn)動(dòng)物體在顆粒物質(zhì)中的動(dòng)力學(xué)過(guò)程及最大穿透深度仿真研究[J];物理學(xué)報(bào);2013年13期

，

本文編號(hào)：1732511