This research programme considers both the structural design aspects as well as the construction aspects. The programme is divided into the following essential work packages:
WP1: The conceptual design of modular connections will be explored. A workshop with designers, manufacturers and contractors will be organised aiming to understand how the manufacturing processes have affected the design of connections and vice-versa.
WP2: Design provisions for flexibility in handling, installation, use, disassembly, and reuse will be considered for: (i) flat-pack, (ii) composite and (iii) hybrid modular unit types. Structural topology optimisation tools will be employed to generate connection designs. At this stage, Expanded | Laing O’Rourke Group will offer specific advice on the assembly, handling and disassembly of modular units to maximise the benefits in the construction programme. Altair-Optistruct will be used to define the objective functions and constraints followed by morphogenesis and mesh-topology editing processes using Altair-Hyperworks. Organic modelling, digital sculpting, and finite element stress analyses will be conducted using parametric modelling using APDL-Abaqus and Python language towards the aggregation of the connection components which will result to a number of optimum designs.
WP3: A wide range of metallic structural elements can theoretically be printed, yet limited structural members have been tested at a macro-scale. Therefore, the material selection amongst various metal alloys is critical and will be based on the existing knowledge of material performance. The mechanical properties of the components will be tested (coupon tests). The structural behaviour of the 3 optimum connection designs (one per modular type, inter-module connection of the volumetric technique – modular unit/box) will be examined in different loading conditions including fatigue performance to define their lifespan. Static and fatigue (low & high frequency) tests will be carried out in the School’s state-of-the-art Heavy Structures Laboratory. Assessing the performance of the optimised 3D printed connections and their components (bolts, plates, nuts, washers) may reveal design and manufacturing issues related to the particular printing process (Direct Metal Laser Sintering, aka DMLS). In detail, the programme includes: (a) measuring the geometric properties and imperfections, (b) scanning the surface roughness of the printed specimens which affects the stiffness, longevity, and tolerances, and (c) experimental testing under 6 (2-normal, 4-accidental) loading conditions for robustness.
WP4: One connection prototype will be tested (under static loads) at a full-scale modular unit to develop a paradigm case study and investigate the interaction between the existing members and the 3D printed components of the connection.
Proving the suitability of 3D printed connections, a testing campaign will include both inter-module and side connections of the volumetric modular technique as well as of the panelised technique for all three modular types. In addition, full-scale follow-up tests are necessary.
With the support of the core steering group, the stakeholders (experts from design, manufacturing and construction sectors), design recommendations and systematic approaches will be drafted to showcase and increase confidence in using 3D printed connections while promoting quick entry in the UK market.