Abstract 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：

---

Agrawal使用基于分形几何的增量刀具路径 (FGBIT) 在增量形成的几何中包含残余应力

摘要 单点增量板成形 (SPISF) 是众所周知的传统创成式制造工艺的灵活替代方案。在 SPISF 中，要形成的几何体被分割成一系列 2D 切片，塑性变形是通过数控 (NC)、半球形或球端成型工具的逐层移动来实现的。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、恒定 z 增量刀具路径及其变体是 SPISF 常见的常规刀具路径。一些研究人员对这些刀具路径进行了广泛的研究。基于分形几何的增量刀具路径 (FGBIT) 是最近为 SPISF 开发的刀具路径，可改善工艺可成形性和应力分布。与传统刀具路径不同，FGBIT 使成形几何形状的基部区域变形，从而将加工硬化和残余应力引入工件。这可能导致形成高强度部件。本研究调查了成形部件（方杯）基部区域的残余应力分布。此外，还基于 FGBIT 和传统增量刀具路径之间的残余应力分布进行了比较。残余应力已通过使用纳米压痕技术测量。针对传统和基于 FGBIT 的刀具路径研究了压痕周边附近的堆积生成。从实验结果可以看出，在使用 FGBIT 时，由于诱导压缩表面残余应力，成形部件的强度增加，因此，