本文關(guān)鍵詞： 振動(dòng)環(huán)境試驗(yàn) 多軸向振動(dòng) 結(jié)構(gòu)動(dòng)力學(xué)響應(yīng) 振動(dòng)疲勞 疲勞壽命估計(jì)　出處：《南京航空航天大學(xué)》2016年博士論文　論文類型：學(xué)位論文

【摘要】：在航空、交通和機(jī)械等領(lǐng)域中,對(duì)產(chǎn)品和裝備進(jìn)行環(huán)境振動(dòng)試驗(yàn)對(duì)提高其可靠性具有重要意義。當(dāng)前的環(huán)境振動(dòng)試驗(yàn),一般采用在三個(gè)軸向依次進(jìn)行單軸向振動(dòng)試驗(yàn)的方式,來等效產(chǎn)品和裝備在實(shí)際工況下所經(jīng)歷的多軸振動(dòng)環(huán)境。該方法在應(yīng)用過程中可能導(dǎo)致產(chǎn)品出現(xiàn)過試驗(yàn)或欠試驗(yàn)現(xiàn)象,其有效性及其與真實(shí)多軸振動(dòng)環(huán)境的差異性受到業(yè)界廣泛重視�；诖�,本文對(duì)多軸向同時(shí)振動(dòng)與單軸向振動(dòng)疲勞試驗(yàn)開展了對(duì)比研究。研究了典型結(jié)構(gòu)在單軸向振動(dòng)環(huán)境與多軸向振動(dòng)環(huán)境下的動(dòng)力學(xué)響應(yīng)。通過理論分析,有限元仿真和試驗(yàn)驗(yàn)證,探索了結(jié)構(gòu)在不同振動(dòng)工況下動(dòng)力學(xué)響應(yīng)的差異與聯(lián)系,并對(duì)差異產(chǎn)生的原因進(jìn)行了分析。研究結(jié)果表明在各軸向互不相關(guān)的三軸同時(shí)振動(dòng)環(huán)境下,結(jié)構(gòu)的動(dòng)力學(xué)響應(yīng)為各個(gè)方向單軸向振動(dòng)時(shí)引起的動(dòng)力學(xué)響應(yīng)的疊加。若各軸向載荷間存在相關(guān)性,則其相關(guān)性對(duì)結(jié)構(gòu)動(dòng)力學(xué)響應(yīng)存在明顯的影響,并得到了不同軸向載荷間相關(guān)性對(duì)結(jié)構(gòu)動(dòng)力學(xué)響應(yīng)的影響規(guī)律,為不同工況下結(jié)構(gòu)振動(dòng)疲勞失效行為的研究奠定了基礎(chǔ)。提出了適合多軸向振動(dòng)環(huán)境下結(jié)構(gòu)疲勞失效的判定方法。通過激光測(cè)振儀和35670A動(dòng)態(tài)信號(hào)分析儀對(duì)結(jié)構(gòu)的一階固有頻率進(jìn)行跟蹤監(jiān)測(cè);利用動(dòng)態(tài)應(yīng)變測(cè)試系統(tǒng)對(duì)試件缺口部位的應(yīng)變進(jìn)行了實(shí)時(shí)監(jiān)測(cè)。根據(jù)試驗(yàn)數(shù)據(jù)分析了多軸向振動(dòng)環(huán)境下疲勞裂紋擴(kuò)展與固有頻率變化和應(yīng)變變化的關(guān)系,確定了兩種疲勞失效的試驗(yàn)判定準(zhǔn)則,為開展多軸向振動(dòng)疲勞試驗(yàn)奠定了基礎(chǔ)。研究了不同載荷工況下結(jié)構(gòu)的振動(dòng)疲勞失效行為,以及各軸向載荷間相關(guān)性對(duì)結(jié)構(gòu)疲勞失效行為的影響。對(duì)典型試件分別進(jìn)行了多軸向同時(shí)振動(dòng)、單軸向振動(dòng)和單軸向依次振動(dòng)疲勞試驗(yàn),并且對(duì)試驗(yàn)結(jié)果進(jìn)行了對(duì)比分析。研究結(jié)果表明相比于單軸向振動(dòng),試件在多軸向同時(shí)振動(dòng)環(huán)境中的疲勞失效時(shí)間、裂紋源的位置以及裂紋擴(kuò)展方式均存在差異,多軸向同時(shí)振動(dòng)更容易使結(jié)構(gòu)產(chǎn)生疲勞損傷,具有更短的失效時(shí)間。通過改變不同軸向載荷譜間相干系數(shù)和相位角,研究了不同軸向載荷間相關(guān)性對(duì)結(jié)構(gòu)疲勞失效行為的影響,得到了載荷相關(guān)性對(duì)結(jié)構(gòu)疲勞失效行為的影響規(guī)律�；诂F(xiàn)有的多軸疲勞損傷估計(jì)理論,根據(jù)多軸向隨機(jī)振動(dòng)環(huán)境下結(jié)構(gòu)動(dòng)力學(xué)響應(yīng)的特點(diǎn),提出了頻域內(nèi)多軸向振動(dòng)環(huán)境下結(jié)構(gòu)疲勞壽命估計(jì)的方法。該方法采用von Mises等效應(yīng)力功率譜密度將多軸應(yīng)力問題轉(zhuǎn)化為單軸應(yīng)力問題,利用單軸應(yīng)力疲勞壽命估計(jì)的頻域分析方法對(duì)結(jié)構(gòu)疲勞壽命進(jìn)行估計(jì)。計(jì)算了典型構(gòu)件在多軸向與單軸向隨機(jī)激勵(lì)下的疲勞壽命,并與實(shí)驗(yàn)結(jié)果進(jìn)行了對(duì)比驗(yàn)證。對(duì)構(gòu)件在多軸向同時(shí)激勵(lì)與單軸向依次激勵(lì)的疲勞損傷結(jié)果進(jìn)行了對(duì)比分析,從理論上研究了多軸向振動(dòng)環(huán)境下結(jié)構(gòu)振動(dòng)疲勞的多軸效應(yīng)。
[Abstract]:In the fields of aviation, traffic and machinery, environmental vibration testing of products and equipment is of great significance to improve their reliability. The method may lead to the phenomenon of product being tested or undertested in the application of the method, which is equivalent to the multi-axis vibration environment experienced by the products and equipment under actual working conditions. Its effectiveness and its difference from the real multi-axis vibration environment have attracted wide attention in the industry. In this paper, the dynamic responses of typical structures under uniaxial vibration and uniaxial vibration are studied by means of theoretical analysis, finite element simulation and experimental verification. The difference and relation of the dynamic response of the structure under different vibration conditions are explored, and the causes of the difference are analyzed. The dynamic response of the structure is the superposition of the dynamic response caused by uniaxial vibration in various directions. If there is a correlation between the axial loads, the correlation has a significant effect on the dynamic response of the structure. The influence of the correlation between different axial loads on the dynamic response of the structure is obtained. It lays a foundation for the study of structural vibration fatigue failure behavior under different working conditions. A method for judging structural fatigue failure under multi-axial vibration environment is proposed. The structural fatigue failure is determined by laser vibration detector and 35670A dynamic signal analyzer. The first order natural frequency is tracked and monitored; The dynamic strain measurement system is used to monitor the strain at the notch of the specimen in real time. Based on the experimental data, the relationship between fatigue crack growth and natural frequency and strain variation in multi-axial vibration environment is analyzed. Two kinds of fatigue failure criteria were determined, which laid a foundation for multi-axial vibration fatigue test. The vibration fatigue failure behavior of structures under different load conditions was studied. And the influence of the correlation between the axial loads on the fatigue failure behavior of the structures. The multiaxial simultaneous vibration, the uniaxial vibration and the uniaxial vibration fatigue tests were carried out respectively for typical specimens. The results show that compared with uniaxial vibration, the fatigue failure time, the location of crack source and the mode of crack propagation are different in multi-axial vibration environment. Multiaxial simultaneous vibration can cause fatigue damage more easily and has shorter failure time. By changing the coherence coefficient and phase angle between different axial load spectra, the influence of the correlation between different axial loads on the fatigue failure behavior of the structure is studied. The influence of load correlation on fatigue failure behavior of structures is obtained. Based on the existing theory of multiaxial fatigue damage estimation and the characteristics of structural dynamic responses under multi-axial random vibration, the dynamic response of structures is analyzed. In this paper, a method for estimating the fatigue life of structures under multiaxial vibration in frequency domain is presented. The multiaxial stress problem is transformed into uniaxial stress problem by using von Mises equivalent stress power spectrum density. The fatigue life of structures is estimated by frequency domain analysis method of uniaxial stress fatigue life estimation, and the fatigue life of typical members under multiaxial and uniaxial random excitation is calculated. The results of fatigue damage caused by multi-axial excitation and uniaxial excitation are compared and analyzed. The multiaxial effect of structural vibration fatigue in multi-axial vibration environment is studied theoretically.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：O327

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本文編號(hào)：1512992