# Vibration Behaviour of Topologically Optimised Sacrificial Geometries for Precision Machining of Thin-Walled Components

## TL;DR

This paper studies how different stock geometries affect the vibration behavior of 3D-printed thin-walled parts during machining.

## Contribution

The study introduces topologically optimized sacrificial geometries that improve modal performance without increasing material volume.

## Key findings

- Optimized geometries enhance modal performance without increasing stock volume.
- Optimized designs show greater in situ modal changes during machining due to variable material removal.
- Constant and tapered stock designs are less sensitive to vibration compared to optimized variants.

## Abstract

Additive manufacturing (AM) enables the consolidation of components and the integration of new functionalities in metallic parts, but layered fabrication often results in poor surface quality and geometric deviations. Among various surface treatment techniques, machining is often favoured for its capability to enhance not only surface finish but also critical geometric tolerances such as flatness and circularity, in addition to dimensional accuracy. However, machining AM components, particularly thin-walled structures, poses challenges related to unconventional material properties, complex fixturing, and heightened susceptibility to chatter. This study investigates the vibrational behaviour of thin-walled Ti6Al4V components produced via laser powder bed fusion, using a jet-engine compressor blade demonstrator. Four stock envelope designs were evaluated: constant, tapered, and two topologically optimised variants. After fabrication by Laser Powder Bed Fusion, the blades underwent tap testing and subsequent machining to assess changes in modal characteristics. The results show that optimised geometries can enhance modal performance without increasing the volume of the stock material. However, these designs exhibit more pronounced in situ modal changes during machining, due to greater variability in material removal and chip load, which amplifies vibration sensitivity compared to constant or tapered stock designs.