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首頁> 外文學(xué)位 >Efficient numerical techniques for predicting process-induced stresses and deformations in composite structures.
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Efficient numerical techniques for predicting process-induced stresses and deformations in composite structures.

機(jī)譯：用于預(yù)測復(fù)合結(jié)構(gòu)中過程引起的應(yīng)力和變形的有效數(shù)值技術(shù)。

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摘要

During the last two decades of research work in numerical modelling of autoclave processing composite structures, several models have been developed ranging from simple one-dimensional elastic to sophisticated three dimensional viscoelastic models. Some of the common problems faced by these numerical models are the non-familiarity of general users with these models, their non-versatility, their inefficiency when running large problems and the interpretation and validation of the results produced by these models.; The main objective of this research work is to initiate the development of the next generation process model for autoclave processing of composite structures to address the above problems. This development is carried out by building on the already established knowledge of process modelling within the UBC Composites Group. The developed next generation process model consists of a set of numerical tools which range in complexity from a simple and robust closed-form analytical tool to a more general and adaptive shell-based finite element analysis tool that provides a modeller with a choice depending on the time and cost constraints.; According to the developed closed-form solution, the axial stress variation in the thickness direction of a flat composite part varies exponentially with the through-thickness coordinate and its gradient depends on the part material and geometrical properties. It is shown that the process-induced unbalanced moment develops mainly at the initial stages of the curing process where the through-thickness stress gradient is significant.; The process-induced effects in a curved part due to the thermal strain mismatch between the part and the tool in the tangential direction is similar to the process-induced effects in a flat part. Apart from the tangential thermal strain mismatch, the radial thermal strain mismatch between the part and the tool also induces stresses in a curved part. These stresses are due to the radial and tangential constraints applied by the tool on the part to conform the part to the tool shape. The unbalanced moment due to these stresses mostly develop at the cool-down portion of the cure cycle when the material is fully cured.
機(jī)譯：在高壓釜處理復(fù)合材料結(jié)構(gòu)的數(shù)值建模的最后二十年的研究工作中，已經(jīng)開發(fā)了多種模型，從簡單的一維彈性模型到復(fù)雜的三維粘彈性模型。這些數(shù)值模型面臨的一些常見問題是普通用戶對這些模型不熟悉，它們的不通用性，運(yùn)行大問題時效率低下以及這些模型產(chǎn)生的結(jié)果的解釋和驗證。這項研究工作的主要目的是啟動下一代工藝模型的開發(fā)，以處理復(fù)合結(jié)構(gòu)的高壓釜，以解決上述問題。這項開發(fā)是基于UBC Composites集團(tuán)內(nèi)部已經(jīng)建立的過程建模知識進(jìn)行的。所開發(fā)的下一代過程模型包括一組數(shù)值工具，其復(fù)雜程度從簡單而健壯的封閉形式分析工具到更通用的基于殼的自適應(yīng)有限元分析工具，這些模型為建模者提供了取決于模型的選擇。時間和成本的限制。根據(jù)已開發(fā)的封閉形式解決方案，扁平復(fù)合材料零件在厚度方向上的軸向應(yīng)力變化會隨厚度方向的坐標(biāo)呈指數(shù)變化，其梯度取決于零件的材料和幾何特性。結(jié)果表明，過程引起的不平衡力矩主要在固化過程的初始階段發(fā)展，該過程中貫穿厚度的應(yīng)力梯度很大。由于零件和工具在切線方向上的熱應(yīng)變不匹配而導(dǎo)致的彎曲零件中的加工引起的效果類似于扁平零件中的加工引起的效果。除了切向熱應(yīng)變不匹配外，零件與工具之間的徑向熱應(yīng)變不匹配也會在彎曲零件中引起應(yīng)力。這些應(yīng)力歸因于工具在零件上施加的徑向和切向約束，以使零件與工具形狀一致。當(dāng)材料完全固化時，由于這些應(yīng)力引起的不平衡力矩主要在固化周期的冷卻部分產(chǎn)生。

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    The University of British Columbia (Canada).;

  • 授予單位 The University of British Columbia (Canada).;
  • 學(xué)科 Applied Mechanics.
  • 學(xué)位 Ph.D.
  • 年度 2007
  • 頁碼 301 p.
  • 總頁數(shù) 301
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類 應(yīng)用力學(xué);
  • 關(guān)鍵詞

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