發(fā)布時間：2018-12-07 12:15

【摘要】：由于泡沫鋁芯中含有大量的胞孔,泡沫鋁夾層板在承受較大的撞擊破壞時,可以產(chǎn)生較大的塑性變形,從而在變形過程中可以吸收大量的能量。然而,在實際應(yīng)用中,泡沫鋁夾層板與其它板材連接使用時有許多缺陷,連接處受力不均,連接不穩(wěn)固,都會給局部甚至整體結(jié)構(gòu)性能帶來嚴重的影響,因此,泡沫鋁夾層板與致密板材的連接問題以及對其連接部位強度的合理加強也是今后研究的一個重要話題。在與其他板材進行連接之前,首先得對泡沫鋁夾層板進行前期的薄化處理,將泡沫鋁夾層板連接的一端進行局部壓實,以便滿足連接要求�；谏鲜鲈�,對泡沫鋁夾層板的局部壓縮性能開展了研究,具體研究的內(nèi)容和成果如下:首先,對發(fā)泡過程進行理想假設(shè)的基礎(chǔ)上,建立了三種二維隨機模型和一種三維隨機球模型,通過調(diào)節(jié)模型生成界面,控制模型的長度、寬度和孔隙率等參數(shù),可以很方便的生成所需模型。其次,選用泡沫鋁夾層板二維隨機圓模型,通過有限元分析軟件ANSYS/LS-DYNA,對泡沫鋁夾層板在不同加載速率下的壓縮行為進行了仿真研究。在準靜態(tài)壓縮的過程中,泡沫鋁夾層板的塑性變形首先發(fā)生在孔壁薄弱處,而在高加載速率下,泡沫鋁夾層板首先在壓縮面附近發(fā)生變形,產(chǎn)生局部密實。在動態(tài)加載速率下,泡沫鋁夾層板底部面板的應(yīng)力應(yīng)變曲線出現(xiàn)一定的延遲,且隨著加載速率的增加,延遲的時間也會隨著增加。另外,基于泡沫鋁夾層板的二維隨機圓模型,通過使用正交模擬實驗、極差分析和方差分析,研究了孔隙度、孔徑、加載速率和泡沫鋁芯厚度對泡沫鋁夾層板的能量吸收性能的影響。研究結(jié)果表明此四種變量對泡沫鋁夾層板的能量吸收性能的影響程度依次如下:孔隙度P胞孔半徑R加載速率V泡沫鋁芯厚度H。此外,隨著孔隙度、孔徑的增加,泡沫鋁夾層板吸收的能量逐漸地減小,而隨著加載速率的增加,泡沫鋁夾層板吸收的能量逐漸地增加,泡沫鋁芯的厚度對泡沫鋁夾層板的能量吸收性能影響很小。最后,在電子萬能試驗機上,分別對不同孔徑、孔隙度的泡沫鋁夾層板進行了準靜態(tài)局部壓縮性能研究。泡沫鋁夾層板的承載能力與孔徑大小和孔隙度大小呈反比例關(guān)系,隨著孔徑和孔隙度地增加,其承載能力逐漸地減小。由于泡沫鋁夾層板基質(zhì)材料是鋁硅基體,應(yīng)力應(yīng)變曲線有明顯地抖動。通過仿真和實驗對比,發(fā)現(xiàn)兩者應(yīng)力應(yīng)變曲線的變化趨勢基本一致,數(shù)值相差較小,通過理論分析闡述了曲線變化的機理,進一步驗證了實驗結(jié)果的正確性以及數(shù)值模擬的可行性。
[Abstract]:Because there are a large number of cellular holes in the aluminum foam core, the foam aluminum sandwich plate can produce large plastic deformation when it is subjected to large impact damage, thus absorbing a large amount of energy in the process of deformation. However, in practical application, there are many defects in the connection of foam aluminum sandwich plate with other plates. The joint is not uniform in force, and the connection is unstable, which will bring serious influence to the local and even the whole structure performance. It is also an important topic to study the connection between foam aluminum sandwich plate and compact plate and the reasonable strengthening of the strength of the joint part in the future. Before connecting with other plates, the foam aluminum sandwich plate should be thinned in the early stage, and the one end of the foam aluminum sandwich plate should be partially compacted in order to meet the connection requirements. Based on the above reasons, the local compression performance of aluminum foam sandwich plate is studied. The specific research contents and results are as follows: first, on the basis of the ideal assumption of foaming process, Three two-dimensional stochastic models and a three-dimensional random sphere model are established. By adjusting the interface of the model and controlling the parameters of the model, such as length, width and porosity, the required model can be generated conveniently. Secondly, the compression behavior of aluminum foam sandwich plate under different loading rates is simulated by finite element analysis software ANSYS/LS-DYNA, which is based on the two-dimensional random circle model of aluminum foam sandwich plate. In the process of quasi-static compression, the plastic deformation of the aluminum foam sandwich plate first occurs in the weak part of the hole wall, while at high loading rate, the plastic deformation of the foam aluminum sandwich plate first occurs near the compression surface, resulting in local compaction. At the dynamic loading rate, the stress-strain curve of the bottom panel of the aluminum foam sandwich plate has a certain delay, and with the increase of the loading rate, the delay time will also increase. In addition, based on the two-dimensional random circle model of aluminum foam sandwich plate, the porosity and pore size are studied by means of orthogonal simulation experiment, range analysis and variance analysis. The effect of loading rate and thickness of aluminum foam core on the energy absorption of aluminum foam sandwich plate. The results show that the influence of these four variables on the energy absorption performance of aluminum foam sandwich plate is as follows: porosity P cell radius R loading rate V foam aluminum core thickness H. In addition, with the increase of porosity and pore size, the energy absorbed by the foam aluminum sandwich plate decreases gradually, while with the increase of loading rate, the energy absorbed by the foam aluminum sandwich plate increases gradually. The thickness of aluminum foam core has little effect on the energy absorption of aluminum foam sandwich plate. Finally, the quasi-static local compression properties of aluminum foam sandwich plates with different pore sizes and porosity were studied on an electronic universal testing machine. The bearing capacity of aluminum foam sandwich plate is inversely proportional to the pore size and porosity, and decreases gradually with the increase of pore size and porosity. Because the matrix material of aluminum foam sandwich plate is aluminum-silicon matrix, the stress-strain curve jitter obviously. Through the comparison of simulation and experiment, it is found that the variation trend of stress-strain curve is basically the same, and the difference of numerical value is small. The mechanism of curve variation is explained through theoretical analysis. The correctness of the experimental results and the feasibility of numerical simulation are further verified.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG146.21;TB383.4

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