Analysis into Differences between the Buckling in Single-Point and Two-Point Incremental Sheet Forming of Components for Self-Supporting Sheet Metal Structures

Abstract

In the architecture and construction sector the trend for individualization is often expressed in complex-shaped freeform buildings. Due to missing universal and mature construction methods for freeform buildings, they are usually realized with customized solutions that often include massive, material-consuming substructures, while the visible skin has neither structural nor functional properties. In this context a new concept for self-supporting lightweight structures for the realization of free-form surfaces and the production of the corresponding components has recently been proposed. Taking into account the large part dimensions and the varying part geometries in this application a flexible production chain based on incremental sheet forming has been developed and optimized. It has been validated by producing six-sided large-scale pyramids in 140 similar variants which were assembled to a self-supporting free-form demonstrator. Two-point incremental sheet forming (TPIF) was used with a universal partial supporting tool with the goal to produce all variants without dedicated tooling. Although the majority of pyramids was produced successfully with the applied TPIF strategy, there was a small number of parts with a very asymmetric shape that showed severe buckling in the side walls. For a detailed analysis of this observation the asymmetry was quantified using a wall angle ratio. Subsequently, a single-point incremental sheet forming (SPIF) strategy was successfully applied as an approach to avoid buckling. The results confirm the assumption that the circumferential expansion in SPIF suppresses buckling due to tensile stresses in the side walls, whereas the circumferential compression in TPIF triggers buckling due to the compressive stresses in the side walls.

Energy consumption, carbon emissions, product cost, and process time in incremental sheet forming process: A holistic review from sustainability perspective

“…It has broadened its application domain since its emergence. This method has applications in numerous sectors such as biomedical sector (denture base, 44 ankle prosthesis, 45 foot orthosis, facial, cranial and cadaver implants, 46–55 knee implants, 56 surgical tools 57 ) and architectural industry (decorative elements and artifacts, 3D roof structure at RWTH, 58 sandwich panels, 59 historic façade construction 32 ). Other prototyping applications cover in aeronautic industry (Gas Turbine diffuser cone, 32 airfoils 60 ), and automotive sector (vehicle head lights reflector, 61 engine intake parts, and heat shields, 62 car body, 63 car fender, 64 car tail light bracket, 65 powertrain guards, 32 motorcycle exhaust pipe cover, 66 Ford Motors logo plate, 67 hood parts of Honda S800, Toyota iQ logo mark on side door panel, 68 and other general parts and dies (shower basin molds for thermoforming, 69 solar cooker, 70 HVAC baffles for efficiency, HVAC shrouds for flow pattern, 32 and bullet train (Shinkansen) components 67 ).…”