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Reprint of: Residual stress inclusion in the incrementally formed geometry using Fractal Geometry Based Incremental Toolpath (FGBIT)
Journal of Materials Processing Technology ( IF 6.3 ) Pub Date : 2020-02-04 , DOI: 10.1016/j.jmatprotec.2020.116623
Harish Kumar Nirala , Anupam Agrawal

Single Point Incremental Sheet Forming (SPISF) is a well-known flexible alternative to conventional generative manufacturing processes. In SPISF, the geometry to be formed is fragmented into series of 2D slices and the plastic deformation is achieved through layer by layer movement of a Numerically Controlled (NC), hemispherical or ball end forming tool. The whole plastic deformation is the sum of all localized strains developed during each increment. Spiral, constant z incremental toolpaths, and their variants are common conventional toolpaths for SPISF. Several researchers have investigated these toolpaths extensively. Fractal Geometry Based Incremental Toolpath (FGBIT) is a recently developed toolpath for SPISF that improves the process formability and stress distribution. Unlike conventional toolpaths, FGBIT deforms the base region of the formed geometry which induces work hardening and residual stresses into the work piece. This may lead to the forming of high strength components. The residual stress distribution over the base region of the formed component (square cup) has been investigated in this study.

Further, a comparison based on residual stress distribution between FGBIT and conventional incremental toolpaths is presented. Residual stresses have been measured by using nanoindentation technique. Pile up generation near the periphery of the indent is investigated for conventional and FGBIT based toolpaths. It has been observed from the experimental results that, the strength of the formed component increases due to induced compressive surface residual stresses while using FGBIT hence, metal components with high fatigue life and better strength-to-weight ratio can be formed.



中文翻译:

转载:使用基于分形几何的增量刀具路径(FGBIT)将残余应力包含在逐渐形成的几何中

单点增量片材成型(SPISF)是传统生成制造工艺的众所周知的灵活替代方法。在SPISF中,要形成的几何形状被分成一系列2D切片,并且通过数控(NC),半球形或球形端部成形工具的逐层运动来实现塑性变形。整个塑性变形是每个增量过程中产生的所有局部应变的总和。螺旋形,恒定的z增量刀具路径及其变体是SPISF的常见常规刀具路径。一些研究人员已经广泛研究了这些工具路径。基于分形几何的增量工具路径(FGBIT)是SPISF的最新开发工具路径,可改善工艺可成形性和应力分布。与传统的刀具路径不同,FGBIT使所形成几何形状的基础区域变形,从而导致工件硬化和残余应力进入工件。这可能导致形成高强度组件。在这项研究中,已研究了成型零件(方形杯)基部区域的残余应力分布。

此外,提出了一种基于残余应力分布的FGBIT与常规增量刀具路径之间的比较。残余应力已通过使用纳米压痕技术进行了测量。对于常规的和基于FGBIT的刀具路径,研究了压痕周围附近的堆积生成。从实验结果已经观察到,在使用FGBIT的同时,由于感应的压缩表面残余应力,所形成的部件的强度增加,因此,可以形成具有高疲劳寿命和更好的强度重量比的金属部件。

更新日期:2020-02-04
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