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首頁> 外文學(xué)位 >THE EFFECTS OF CURE TEMPERATURE AND TIME ON THE BULK TENSILE AND FRACTURE BEHAVIOR OF A STRUCTURAL ADHESIVE.
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THE EFFECTS OF CURE TEMPERATURE AND TIME ON THE BULK TENSILE AND FRACTURE BEHAVIOR OF A STRUCTURAL ADHESIVE.

機(jī)譯：固化溫度和時(shí)間對結(jié)構(gòu)膠粘劑本體拉伸和斷裂行為的影響。

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摘要

The effects of thermal cure and cool-down conditions as well as the presence of carrier cloth on the room temperature bulk tensile and Mode-I fracture properties of a rubber-modified structural adhesive have been investigated experimentally. The model adhesives used in this work are Metlbond 1113 (with carrier cloth) and Metlbond 1113-2 (without carrier cloth) solid film modified epoxy resins. The possibility of optimizing the cure conditions via bulk tensile and fracture behavior are determined. Based on a simple differential thermal analysis methodology, and using a single first order kinetic reaction model, variations in the degree of cure of the model adhesives subjected to different cure schedules are predicted. It is shown that for a fixed cool-down condition and cure time duration, both the tensile strength and rigidity values can be maximized over a range of cure temperatures. By increasing the cure time duration, higher peak strength and rigidity values are obtained at lower cure temperatures. The slow cool-down condition is shown to increase the optimum tensile properties. The presence of carrier cloth appears to increase the optimum strength values for the fast cool-down condition and also the extent of void formation during the cure process. The short term viscoelastic tensile stress relaxation behavior of Metlbond 1113 is shown to be affected by the thermal cure history. Using the Modified Bingham model, the relaxation times seem to increase as higher cure temperatures are used. The Mode-I fracture toughness (K(,Ic)) of the model adhesives have been determined using the SEN tension geometry over a range of cure conditions. It is found that the optimum K(,Ic)'s are obtained at low cure temperatures--long cure time conditions in the absence of carrier cloth when the slow cool-down condition is employed. The fracture energy values (G(,Ic)) are found using the small-scale crack tip yielding assumption and the bulk tensile properties. It is found that the optimum G(,Ic)'s are obtained at high temperature - short time cure conditions in the absence of carrier cloth when the slow cool-down condition is used. SEM fractographic and microscopic examinations reveal that changes in cure conditions result in varying degrees of stress whitening ahead of the crack tip in the fracture specimens and along the surface for the tensile specimens. Based on the application of a modified bilinear form of Ramberg-Osgood model, the stress-strain behavior as well as the stress whitening stress levels for Metlbond 1113 are predicted and agree well with the experimental results.
機(jī)譯：實(shí)驗(yàn)研究了熱固化和冷卻條件以及載體布的存在對橡膠改性結(jié)構(gòu)膠粘劑的室溫整體拉伸和I型斷裂性能的影響。用于這項(xiàng)工作的模型粘合劑是Metlbond 1113（帶載體布）和Metlbond 1113-2（不帶載體布）固體膜改性環(huán)氧樹脂。確定了通過整體拉伸和斷裂行為優(yōu)化固化條件的可能性?；诤唵蔚牟顭岱治龇椒?，并使用單個(gè)一階動力學(xué)反應(yīng)模型，可以預(yù)測經(jīng)受不同固化時(shí)間表的模型粘合劑的固化程度變化。結(jié)果表明，對于固定的冷卻條件和固化時(shí)間，在一定的固化溫度范圍內(nèi)，拉伸強(qiáng)度和剛度值都可以最大化。通過增加固化時(shí)間，在較低的固化溫度下可獲得較高的峰值強(qiáng)度和剛度值。顯示出緩慢的冷卻條件可以增加最佳的拉伸性能。載體布的存在似乎增加了快速冷卻條件下的最佳強(qiáng)度值，并且還增加了固化過程中形成空隙的程度。已顯示，Metlbond 1113的短期粘彈性拉伸應(yīng)力松弛行為受熱固化歷史的影響。使用改良的賓厄姆模型，松弛時(shí)間似乎隨著使用更高的固化溫度而增加。在一定范圍的固化條件下，已使用SEN張力幾何結(jié)構(gòu)確定了模型粘合劑的I型斷裂韌性（K（，Ic））。已經(jīng)發(fā)現(xiàn)，當(dāng)采用緩慢冷卻條件時(shí)，在低固化溫度下，在沒有載體布的情況下，較長的固化時(shí)間條件下，可以獲得最佳的K（，Ic）。斷裂能值（G（，Ic））是使用小規(guī)模裂紋尖端屈服假設(shè)和整體拉伸性能得出的。發(fā)現(xiàn)當(dāng)使用緩慢的冷卻條件時(shí)，在沒有載布的情況下在高溫-短時(shí)間固化條件下獲得最佳的G（，Ic）。 SEM形貌和顯微檢查表明，固化條件的變化會導(dǎo)致斷裂樣品中裂紋尖端之前以及沿拉伸樣品表面的應(yīng)力變白程度不同?；诟倪M(jìn)的雙線性形式的Ramberg-Osgood模型的應(yīng)用，預(yù)測了Metlbond 1113的應(yīng)力-應(yīng)變行為以及應(yīng)力增白應(yīng)力水平，并與實(shí)驗(yàn)結(jié)果吻合良好。

著錄項(xiàng)

  • 作者

    JOZAVI, HOOSHANG.;

  • 作者單位

    Clarkson University.;

  • 授予單位 Clarkson University.;
  • 學(xué)科 Engineering Materials Science.
  • 學(xué)位 Ph.D.
  • 年度 1987
  • 頁碼 245 p.
  • 總頁數(shù) 245
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類 工程材料學(xué);
  • 關(guān)鍵詞

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