本文選題：數(shù)值模擬 + 疲勞強(qiáng)度評定�。� 參考：《中國鐵道科學(xué)研究院》2014年博士論文

【摘要】：高速鐵路顯著縮短了出行時間，為旅客出行帶來極大方便，我國已經(jīng)具備高速鐵路列車的自主研發(fā)和產(chǎn)業(yè)化生產(chǎn)能力，然而就其關(guān)鍵走行部件——車輪而言，目前主要依賴進(jìn)口，這一問題影響并制約我國高速列車的國產(chǎn)化程度。研究和開發(fā)具有自主知識產(chǎn)權(quán)的動車組車輪，實(shí)現(xiàn)動車組車輪自主創(chuàng)新和國產(chǎn)化，對于降低車輪采購和運(yùn)用檢修成本、優(yōu)化鐵路資源配置等具有重要意義。 開展動車組車輪疲勞性能數(shù)值仿真和評定方法研究是動車組車輪自主創(chuàng)新的關(guān)鍵環(huán)節(jié)，車輪服役性能與輪型設(shè)計、材質(zhì)性能、熱處理工藝、輪軌匹配及踏面?zhèn)麚p等諸多因素有關(guān)，是眾多因素共同作用下的車輪綜合表現(xiàn)；需要從車輪疲勞強(qiáng)度、熱處理殘余應(yīng)力、輪軌接觸強(qiáng)度、輪輞裂紋及其損傷容限等方面開展研究，分析各因素對車輪性能的影響。 結(jié)合輻板裂紋萌生的物理特性和輻板表面應(yīng)力特點(diǎn)，提出了以全尺寸車輪彎曲疲勞極限表征疲勞強(qiáng)度極限狀態(tài)的主應(yīng)力法和Crossland準(zhǔn)則，并將二者結(jié)合提出了一種動車組車輪疲勞強(qiáng)度評定方法。在測試實(shí)物力學(xué)性能基礎(chǔ)上擬合了車輪輻板S-N曲線和ε-N曲線，結(jié)合應(yīng)力準(zhǔn)則、應(yīng)變準(zhǔn)則、能量準(zhǔn)則等3類準(zhǔn)則和4個典型動車組車輪輪型開展了評定方法適用性分析。新方法評定效果的穩(wěn)定性較強(qiáng)，適用于各型動車組車輪的疲勞強(qiáng)度評定，易于編程，適合工程應(yīng)用。 結(jié)合理論推導(dǎo)和試驗(yàn)，給出了車輪熱處理模型中強(qiáng)制對流系數(shù)、相變潛熱等關(guān)鍵參數(shù)的確定方法。建立了CRH5型動車組車輪整個熱處理過程的溫度場、應(yīng)力場數(shù)值仿真模型，通過與實(shí)測溫度和殘余應(yīng)力比較，對模型的正確性和可靠性進(jìn)行了驗(yàn)證。首次定量給出了熱處理殘余應(yīng)力和踏面鏇修量的關(guān)系，以及二者對輻板疲勞強(qiáng)度的影響。分析發(fā)現(xiàn)，車輪熱處理產(chǎn)生的殘余應(yīng)力有利于提高輪軌接觸疲勞壽命，以CRH5-XP55車輪為例，熱處理殘余應(yīng)力提高接觸疲勞壽命的計算值約3倍以上。 在實(shí)測真實(shí)應(yīng)力-應(yīng)變曲線、疲勞數(shù)據(jù)的基礎(chǔ)上建立了彈塑性輪軌接觸有限元模型和疲勞分析模型，開展了相關(guān)仿真計算。研究表明，具有良好輪軌接觸幾何關(guān)系的車輪踏面，一般也具有良好的輪軌接觸應(yīng)力分布規(guī)律和接觸疲勞性能，綜合考慮輪軌接觸幾何、等效錐度、強(qiáng)度薄弱點(diǎn)位置以及輪軌接觸疲勞等性能指標(biāo)，LMA踏面的綜合性能最優(yōu)。車輪輪型對接觸疲勞壽命也有一定程度的影響，采用低徑向剛度車輪可以在一定程度上提高輪軌接觸疲勞強(qiáng)度。 提出了一種塑性應(yīng)力強(qiáng)度因子修正方法，并應(yīng)用于輪輞裂紋損傷容限分析。提出了基于解析解的輪輞淺層裂紋的應(yīng)力強(qiáng)度因子計算方法。結(jié)合有限元子模型技術(shù)和自適應(yīng)網(wǎng)格劃分技術(shù)，建立了輪輞內(nèi)部埋藏型裂紋的任意三維裂紋擴(kuò)展仿真模型。研究表明，直徑不大于1mm的圓形面片裂紋對應(yīng)的應(yīng)力強(qiáng)度因子小于裂紋擴(kuò)展門檻值，因此裂紋不會擴(kuò)展。輪輞埋藏裂紋趨近于踏面表面時，裂紋耦合面趨近圓形；而裂紋遠(yuǎn)離踏面時，裂紋耦合面形狀趨近橢圓并以車輪運(yùn)行方向?yàn)殚L軸。在動車組的軸重范圍內(nèi)，輪輞內(nèi)部萌生的裂紋擴(kuò)展到一定尺寸后，裂紋深度對裂紋擴(kuò)展速率的影響不顯著。
[Abstract]:High speed railway significantly shortens the travel time and brings great convenience to passengers. China has the ability to develop and industrialization of high speed railway trains. However, its key walking parts, wheels, are mainly dependent on imports. This problem affects and restricts the degree of domestic high speed trains in China. It is of great significance to develop EMU wheels with independent intellectual property rights, and to realize independent innovation and localization of the wheels of the EMU. It is of great significance to reduce the cost of the wheel procurement and use the maintenance and optimize the allocation of railway resources.
The research on the fatigue performance simulation and evaluation method of the EMU wheel is the key link of the independent innovation of the wheels of the EMU. The service performance of the wheel is related to the wheel type design, the material performance, the heat treatment process, the wheel rail matching and the tread damage and so on. It is the comprehensive performance of the wheels under the joint action of many factors; it needs to be tired from the wheel fatigue. Strength, heat treatment residual stress, wheel rail contact strength, rim crack and damage tolerance were studied, and the influence of various factors on wheel performance was analyzed.
Combining the physical characteristics of the crack initiation and the surface stress characteristics of the spoke plate, the main stress method and Crossland criterion are proposed to characterize the ultimate state of the fatigue strength by the full size wheel bending fatigue limit, and a method for evaluating the fatigue strength of the EMU wheel is proposed by the combination of the two, and the vehicle is fitted on the basis of the mechanical properties of the test material. The S-N curve and the epsilon -N curve of the wheel spoke board, combined with the 3 types of criteria, such as stress criterion, strain criterion, energy criterion and so on, and 4 typical EMU wheel wheels, the applicability analysis of the evaluation method is carried out. The new method has strong stability, which is suitable for evaluating the fatigue strength of various types of EMU wheels, easy to program and suitable for engineering applications.
Combined with theoretical deduction and experiment, the key parameters such as forced convection coefficient and latent heat of phase change in the wheel heat treatment model are given. The temperature field of the whole heat treatment process of CRH5 type EMU wheel is established, and the numerical simulation model of stress field is established. By comparing with the measured temperature and residual stress, the correctness and reliability of the model are carried out. The relationship between the residual stress of heat treatment and the tread repair quantity and the effect of the two on the fatigue strength of the spoke plate are given for the first time. The analysis shows that the residual stress produced by the wheel heat treatment is beneficial to the increase of the contact fatigue life of the wheel and rail. The calculation value of the residual stress of the heat treatment to increase the fatigue life of the contact fatigue is about 3, with the CRH5-XP55 wheel as an example. More than twice.
On the basis of actual stress-strain curve and fatigue data, the elastoplastic wheel rail contact finite element model and fatigue analysis model are established, and the related simulation calculation is carried out. The research shows that the wheel tread with good wheel rail contact geometry relation is generally also with good contact stress distribution and contact fatigue performance of wheel rail contact. Considering the contact geometry of wheel and rail, the equivalent taper, the position of strength weak point and the wheel rail contact fatigue, the comprehensive performance of the LMA tread is the best. The wheel wheel type has some influence on the contact fatigue life, and the wheel rail contact fatigue strength can be improved to a certain extent by using the low radial stiffness wheel.
A modified method for plastic stress intensity factor correction is proposed and applied to the damage tolerance analysis of rim cracks. A calculation method of stress intensity factor for shallow rim cracks on the rim is proposed based on analytical solution. An arbitrary three-dimensional crack propagation in the inner rim of the rim is established by combining the finite element submodel technique and the adaptive mesh division technique. The simulation model shows that the stress intensity factor of a circular face crack with a diameter of not more than 1mm is less than the crack propagation threshold, so the crack will not expand. When the rim burial crack approaches the surface of the tread, the crack coupling surface approaches the circle; while the crack is far away from the tread, the shape of the crack coupling surface approaches the ellipse and runs on the wheel. In the axle load range of the EMU, the crack propagation to a certain size will not affect the crack propagation rate.

【學(xué)位授予單位】：中國鐵道科學(xué)研究院
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：U266

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