Digital fabrication strategies for timber thin-walled sections

Abstract

A rise in digital fabrication technologies has led to numerous recent advances in the design and manufacture of woodworking joints. Computational generative processes can be used to create a part with integral mechanical attachments for friction-fit, adhesion-less connections between parts. These processes can additionally create machine code for production of such parts on computernumerically controlled (CNC) cutters. This paper investigates such computational processes for digital design and manufacture of timber thin-walled structural sections. Assembly procedures are first presented for rectangular hollow sections and I-sections, with a series of timber prototypes produced to demonstrate their CNC production. An experimental analysis on square hollow sections under uniaxial compressive loading is then conducted. Tight fit digitally-fabricated sections are seen to possess a structural capacity approaching that of the glued sections. Prototypes with different assembly tolerances and grain directions produce a range of novel failure modes and give insight into potential failure paths of digitally-fabricated timber sections.

A Calculation Method for Interconnected Timber Elements Using Wood-Wood Connections

“…The volume transported is no longer minimized, but larger elements can be produced without discontinuities. For the mechanical performance, recent research on wood-wood connections for timber plate structures has shown the potential for standard building elements like walls with flat or curved geometries [20,21].…”

Fabricate 2017

“…This can be partially abated through a fine control of part tolerance to achieve a friction-only fit (Robeller, 2015), or through interlocking geometry which prevents the movement of two parts in all but one direction (Robeller & Weinand, 2016), but such measures can also offset the ease of assembly. In terms of structural capacity, press-fit structures can possess compressive capacity approaching that of the glued sections, but can also be subject to a catastrophic 'pop-off' failure mechanism where sudden loss of friction cohesion causes an explosive bifurcation and complete disassembly (Al-Qaryouti et al, 2016).…”

Hybrid timber-concrete floor panel systems with a novel hollow core construction

“…Notch, tab, and slot joint details are shown in Figure 4.3. Connection tolerance is known to have a strong effect on mechanical performance of digitally-fabricated joints (Al-Qaryouti, Gattas, Shi, & McCann, 2016;Robeller, 2015;Stitic, Robeller, & Weinand, 2018), and so final joint dimensions were found following a calibration study being undertaken on the CNC machines. HFT core joints were manufactured and calibrated by on a Nexus Water Line CNC waterjet cutting machine with a kerf diameter of 0.8mm.…”