本文選題：高溫強(qiáng)度 + 抗熱震性能��； 參考：《重慶大學(xué)》2016年博士論文

【摘要】：先進(jìn)材料是指新近發(fā)展或正在發(fā)展之中的具有比傳統(tǒng)材料性能更為優(yōu)異的一類(lèi)材料。目前,先進(jìn)材料廣泛應(yīng)用于國(guó)防建設(shè)中,并服役于高溫環(huán)境,其服役安全性是亟待解決的一個(gè)關(guān)鍵問(wèn)題,研究這些材料的高溫?zé)釋W(xué)和力學(xué)性能對(duì)此十分重要。本文根據(jù)三類(lèi)先進(jìn)材料的研究現(xiàn)狀,并結(jié)合各個(gè)科學(xué)問(wèn)題的特點(diǎn),采用理論、數(shù)值和試驗(yàn)方法研究了化學(xué)氣相沉積硫化鋅(CVD Zn S),超高溫陶瓷材料(UHTCs)和單晶材料的高溫強(qiáng)度和抗熱震性能,主要開(kāi)展工作如下:(1)通過(guò)在常規(guī)韌性材料拉伸夾具基礎(chǔ)上做改進(jìn),提出了一套操作簡(jiǎn)單、加工方便、經(jīng)濟(jì)的脆性材料單軸直接拉伸強(qiáng)度測(cè)試裝置。測(cè)試裝置及測(cè)試方法的有效性通過(guò)測(cè)試的室溫CVD Zn S單拉強(qiáng)度與三點(diǎn)彎強(qiáng)度的比值與文獻(xiàn)中報(bào)道的其它脆性材料的比值相近,且測(cè)得的單拉強(qiáng)度和三點(diǎn)彎強(qiáng)度服從Weibull統(tǒng)計(jì)分布進(jìn)行了驗(yàn)證。此外,為了設(shè)計(jì)和評(píng)估CVD Zn S頭罩和側(cè)窗,還測(cè)試了從室溫到600°C的直接單拉強(qiáng)度和單軸壓縮強(qiáng)度,并通過(guò)宏微觀(guān)分析得到了CVD Zn S的拉伸和壓縮失效機(jī)理和失效模式。(2)從臨界失效能密度準(zhǔn)則和臨界應(yīng)變準(zhǔn)則出發(fā)建立了立方單晶和六方單晶的溫度相關(guān)性理想拉伸強(qiáng)度模型,從而將單晶材料的溫度相關(guān)性理想拉伸強(qiáng)度和溫度相關(guān)性彈性性質(zhì),定壓比熱容(臨界失效能密度準(zhǔn)則)和線(xiàn)熱膨脹系數(shù)(臨界應(yīng)變準(zhǔn)則)聯(lián)系了起來(lái),進(jìn)而將參考溫度下的理想拉伸強(qiáng)度外推到其它溫度。從理論上研究了立方單晶(W、Al和Fe)和六方單晶(Zr B2、Hf B2和Ti B2)的溫度相關(guān)性理想拉伸強(qiáng)度,特別地,Al是從絕對(duì)零度到材料熔點(diǎn)的。計(jì)算結(jié)果和第一性原理(AI)、分子動(dòng)力學(xué)(MD)和AI MD方法的結(jié)果進(jìn)行了比較,通過(guò)理論分析說(shuō)明了所建模型在預(yù)測(cè)單晶材料理想拉伸強(qiáng)度時(shí)的合理性,且說(shuō)明了立方單晶和六方單晶的高溫失效準(zhǔn)則均為應(yīng)變控制的。(3)成功地將半無(wú)限大體的瞬態(tài)溫度解答應(yīng)用到了UHTC薄板單一熱環(huán)境下熱沖擊瞬態(tài)溫度分布的計(jì)算中,并從熱彈性理論出發(fā)推導(dǎo)了自由薄板的溫度相關(guān)性熱應(yīng)力場(chǎng)模型,從而建立了單一熱環(huán)境下UHTCs的溫度相關(guān)性熱沖擊模型。對(duì)于復(fù)合熱環(huán)境,根據(jù)有限體積法,推導(dǎo)得到了對(duì)流冷卻情形下UHTC熱防護(hù)系統(tǒng)的抗熱震性能計(jì)算模型。所建模型的有效性均通過(guò)與有限元計(jì)算結(jié)果的對(duì)比進(jìn)行了驗(yàn)證。詳細(xì)研究了氣動(dòng)熱環(huán)境和對(duì)流熱環(huán)境下UHTCs的抗熱震性能,定義了第一、二和三類(lèi)熱的邊界條件下的傳熱條件,應(yīng)用傳熱條件的概念得到了陶瓷材料不同熱環(huán)境下的統(tǒng)一抗熱震性能基本規(guī)律,并提出了臨界傳熱條件來(lái)表征陶瓷材料的抗熱震性能。傳熱條件和臨界傳熱條件間的關(guān)系類(lèi)似于應(yīng)力和強(qiáng)度間的關(guān)系。臨界傳熱條件強(qiáng)調(diào)的是材料永不發(fā)生熱沖擊失效,故臨界傳熱條件不但可用于表征材料的抗熱震性能,還可用于工程設(shè)計(jì)中作為安全設(shè)計(jì)參數(shù)。對(duì)UHTC熱防護(hù)系統(tǒng)抗熱震性能的研究表明,對(duì)流冷卻可提高UHTC熱防護(hù)系統(tǒng)的抗升溫?zé)嵴鹦阅?但同時(shí)可能引入新的降溫?zé)釠_擊,為了確保對(duì)流冷卻不會(huì)引起薄板的失效,對(duì)流冷卻時(shí)的傳熱條件應(yīng)小于相應(yīng)的臨界傳熱條件。(4)用理論和有限元數(shù)值模擬的方法詳細(xì)研究了第一、二和三類(lèi)熱邊條下工程中常見(jiàn)的9類(lèi)約束方式和薄板面內(nèi)幾何形狀對(duì)陶瓷構(gòu)件抗熱震性能的影響,給出了這9類(lèi)約束方式的抗熱震性能的排序和如何通過(guò)避免薄板面內(nèi)幾何形狀和約束條件的非對(duì)稱(chēng)性來(lái)提高陶瓷構(gòu)件的抗熱震性能。
[Abstract]:Advanced materials are a kind of materials which have been developed or are developing more well than traditional materials. At present, advanced materials are widely used in the construction of national defense and are serving in high temperature environment. The safety of their service is a key problem to be solved urgently. The study of the thermal and mechanical properties of these materials is very important. Based on the research status of three kinds of advanced materials and the characteristics of various scientific problems, the high temperature strength and thermal shock resistance of chemical vapor deposition zinc sulfide (CVD Zn S), ultra high temperature ceramic materials (UHTCs) and single crystal materials are studied by means of theoretical, numerical and experimental methods. The main work is as follows: (1) through the conventional toughness On the basis of the tensile clamp, a set of simple, convenient and economical single axis tensile strength testing device for brittle materials is proposed. The ratio of the ratio of the single tensile strength to the three point bending strength at room temperature CVD Zn S is close to the ratio of the other brittle materials reported in the article. The measured single tensile strength and three point bending strength were verified by Weibull statistical distribution. In addition, in order to design and evaluate the CVD Zn S head cover and side window, the direct mono tensile strength and uniaxial compression strength from room temperature to 600 degree C were also tested. The tensile and compression failure mechanisms and failure modes of CVD Zn S were obtained by macro and micro analysis. (2) Based on the critical failure energy density criterion and the critical strain criterion, the ideal tensile strength model for the temperature dependence of the cubic and six square crystals was established. The temperature dependent elastic properties of the ideal tensile strength and temperature, the constant pressure ratio heat capacity (Critical inefficiency density criterion) and the linear thermal expansion coefficient (critical stress) were established. The ideal tensile strength of the reference temperature is extrapolated to other temperatures. The ideal tensile strength of the temperature dependence of cubic monocrystal (W, Al and Fe) and six square single crystals (Zr B2, Hf B2 and Ti B2) is theoretically studied. In particular, Al is from absolute zero to material melting point. Calculation results and first principle (AI) are divided. The results of the sub dynamics (MD) and the AI MD method are compared. The reasonableness of the model in predicting the ideal tensile strength of the single crystal material is explained by theoretical analysis, and the high temperature failure criteria of the cubic and six square crystals are all strain controlled. (3) the semi infinite transient temperature solution is successfully applied to the UHTC In the calculation of the transient temperature distribution of the thermal shock in a single thermal environment, the temperature dependent thermal stress field model of the free plate is derived from the thermoelastic theory, and the temperature dependent thermal shock model of UHTCs under a single thermal environment is established. For the complex thermal environment, the convective cooling is derived by the finite volume method. The thermal shock resistance calculation model of the lower UHTC thermal protection system. The validity of the model is verified by the comparison with the results of the finite element calculation. The thermal shock resistance of the UHTCs under the aerodynamic heat environment and the convective heat environment is studied in detail. The heat transfer conditions under the boundary conditions of first, second and three types of heat are defined and the heat transfer conditions are applied. The basic rule of the unified thermal shock resistance of ceramic materials under different thermal conditions is read, and the critical heat transfer conditions are proposed to characterize the thermal shock resistance of the ceramic materials. The relationship between the heat transfer conditions and the critical heat transfer conditions is similar to the relationship between the stress and the strength. The critical heat transfer conditions can be used not only to characterize the thermal shock resistance of the material, but also to be used as a safety design parameter in the engineering design. The study of the thermal shock resistance of the UHTC thermal protection system shows that the convective cooling can improve the thermal shock resistance of the UHTC thermal protection system, but at the same time it may introduce a new thermal shock reduction to ensure the convection cooling. The heat transfer conditions of the convective cooling should be less than the corresponding critical heat transfer conditions. (4) the influence of the 9 types of constraints and the geometric shape of the thin plate on the thermal shock resistance of the ceramic members under the first, second and three types of hot strip is studied by theory and finite element numerical simulation. The thermal shock resistance of the 9 types of constraints and how to improve the thermal shock resistance of the ceramic members can be achieved by avoiding the asymmetry of the geometric and constraint conditions in the thin plate.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：O346
，

本文編號(hào)：2035654