Experimental and computational analysis of rate dependence during cutting of viscoelastic natural product-based model systems

基于粘弹性天然产物的模型系统切割过程中速率依赖性的实验和计算分析

• 批准号: 420422342
• 负责人: Professor Dr.-Ing. Markus Kästner
• 金额: --
• 依托单位: Institut für Naturstofftechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/420422342?language=en
• 关键词: Experimental; computational; analysis; rate; dependence

Cutting is characterized by a complex interplay of deformation, fracture and friction processes. In the case of viscoelastic materials, all these processes depend significantly on the applied cutting velocity. The increase of cutting velocity or the reduction of temperature at cutting may consequently lead to a transition from ductile to brittle fracture behavior.The aim of the proposed project is to analyze the complex velocity-dependent cutting process with respect to deformation and fracture on a model basis and to describe the transition from ductile to brittle both in the experiment and in a numerical model. The experimental investigations are carried out for two viscoelastic natural product-based model systems, where one system is based on a hydrated protein matrix and the second system is based on sugar. Their deformation and fracture be-havior will be analyzed at various temperatures and velocities. Experimentally unreachable strain rate ranges will be accessed by applying temperature-time superposition, TTS. The parameters de-termined experimentally and by TTS then build the basis for the numerical modeling of the velocity- and temperature-dependent deformation behavior at large deformations using a viscoelastic material model. The determined fracture toughness will be the basis for a phase-field model to be developed for simulating the velocity-dependent fracture behavior, with special emphasis being placed on the transition from ductile to brittle failure at high velocities. In combination with the viscoelastic material model, this phase field model will be applied to simulate cutting processes and cutting tests will be carried out over a large velocity range. Simulation runs and experimental cutting sequences will finally be evaluated with regard to velocity dependency. Additional tests on real natural material will be carried out to validate the results and their transferability.Therefore, the applied project generates a numerical model of the cutting process which is the basis for a future systematic process development and optimization of the process parameters for the cutting of natural materials, based on the experimental analysis of the velocity-dependent defor-mation and fracture behavior. Furthermore, routines are provided for the combined direct-indirect analysis of the material behavior by means of experiment and TTS, which may further be used for analyzing thermomechanical effects that also occur during cutting.

切割的特点是变形、断裂和摩擦过程的复杂相互作用。对于粘弹性材料，所有这些过程在很大程度上取决于所施加的切割速度。切削速度的提高或切削温度的降低可能导致从延性断裂行为向脆性断裂行为的转变。本项目的目的是在模型的基础上分析复杂的与速度相关的加工过程的变形和断裂，并在实验和数值模型中描述从延性到脆性的转变。对两种粘弹性天然产物模型体系进行了实验研究，其中一种体系基于水合蛋白质基质，第二种体系基于糖。将分析它们在不同温度和速度下的变形和断裂行为。实验上无法达到的应变速率范围将通过应用温度-时间叠加TTS来获得。由实验和TTS确定的参数为使用粘弹性材料模型对大变形时的速度和温度相关的变形行为进行数值模拟奠定了基础。确定的断裂韧性将是建立相场模型的基础，以模拟速度相关的断裂行为，特别强调在高速下从延性破坏到脆性破坏的转变。该相场模型将与粘弹性材料模型相结合，用于模拟切割过程，并在较大的速度范围内进行切割试验。最后将根据速度相关性对模拟运行和实验切割序列进行评估。为了验证结果及其可转移性，还将对真实的天然材料进行额外的试验。因此，应用项目基于对自然材料的速度相关变形和断裂行为的实验分析，生成了切割过程的数值模型，该模型是未来系统的天然材料切割工艺开发和工艺参数优化的基础。此外，还提供了通过实验和TTS对材料行为进行直接-间接相结合的分析程序，该程序可进一步用于分析在切割过程中也发生的热机械效应。