今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 1 篇
Examining infrared thermography based approaches to rapid fatigue characterization of additively manufactured compression molded short fiber thermoplastic composites
P. Pathak, S. Gururaja, V. Kumar, D. Nuttall, A. Mahmoudi, M.M. Khonsari, U. Vaidya
doi:10.1016/j.compstruct.2024.118610
研究基于红外热成像的增材制造压缩成型短纤维热塑性复合材料快速疲劳表征方法
A novel additive manufacturing (AM) methodology combined with a compression molding (CM) process has been previouslydeveloped to optimize the microstructure of short fiber thermoplastic (SFTs) composites with higher fiber alignment and lower porosity, yielding superior stiffness, strength, and structural integrity. The current work examines the efficacy of the ‘passive’ infrared thermography (IRT) techniques for rapid fatigue characterization of SFTs that use the surface temperature evolution during cyclic loading due to self-heating as a fatigue indicator. A comparison of fatigue limits obtained from traditional stress-life (SN) (≈53.1% σ_uts) and IRT (≈54.1% σ_uts) shows a close match. However, the SN curve required 18 specimens and two weeks of continuous cyclic testing, while IRT used three specimens with 5 h of testing. Thus, the IRT approach provides an accelerated testing framework for rapidly estimating the fatigue limit. Additionally, existing phenomenological approaches to IRT fatigue characterization have been examined.
之前开发的一种新型增材制造(AM)方法与压缩成型(CM)工艺相结合,可优化短纤维热塑性塑料(SFT)复合材料的微观结构,使其具有更高的纤维排列度和更低的孔隙率,从而获得优异的刚度、强度和结构完整性。目前的工作研究了 “被动 ”红外热成像(IRT)技术在 SFT 快速疲劳表征方面的功效,该技术使用循环加载期间由于自加热而产生的表面温度变化作为疲劳指标。通过比较传统应力寿命(SN)(≈53.1% σ_uts)和 IRT(≈54.1% σ_uts)获得的疲劳极限,结果显示两者非常接近。不过,SN 曲线需要 18 个试样和两周的连续循环测试,而 IRT 只需要 3 个试样和 5 小时的测试。因此,IRT 方法为快速估计疲劳极限提供了一个加速测试框架。此外,我们还研究了 IRT 疲劳表征的现有现象学方法。
Joule heating of carbon fibre tapes – A low-cost approach for automated dry fibre deposition
Shimin Lu, Peihao Song, Lee Harper, Thomas Turner
doi:10.1016/j.compositesa.2024.108498
碳纤维带的焦耳加热-一种低成本的自动干纤维沉积方法
Joule heating is potentially a low-cost option for activating the binder on the surface of carbon fibre tapes during automated dry fibre placement (ADFP). In this paper, the electrical contact resistance between a carbon fibre tape and cylindrical electrodes is characterised experimentally using a tabletop rig to replicate the process conditions encountered during ADFP. This rig is used to study a range of wrap angles, fibre tensions and temperatures to inform the design of a Joule heating setup for a lab-scale ADFP fibre deposition rig. A validated model has been developed to predict the tape temperature at the nip point for different current inputs and deposition velocities. Increasing both fibre tension and wrap angle are found to reduce contact resistance and increase heating efficiency. A nip point temperature of 200 °C can be achieved by Joule heating for a single carbon fibre tape at a deposition velocity of 100 m m/s, using a power of 110 W. This equates to a 17 % reduction in energy compared to laser heating.
焦耳加热是一种潜在的低成本选择,可以在自动干纤维放置(ADFP)过程中激活碳纤维带表面的粘合剂。在本文中,碳纤维胶带和圆柱形电极之间的电接触电阻进行了实验表征,使用桌面设备来复制ADFP过程中遇到的工艺条件。该装置用于研究一系列缠绕角度、纤维张力和温度,为实验室规模ADFP纤维沉积装置的焦耳加热装置设计提供信息。在不同的电流输入和沉积速度下,建立了一个有效的模型来预测带在掐点处的温度。增加纤维张力和包覆角可以降低接触电阻,提高加热效率。通过焦耳加热,以100 m m/s的沉积速度,使用110 W的功率,可以实现200 °C的夹点温度。与激光加热相比,这相当于减少了17% %的能量。