Incorporating additive manufacturing (AM) constraints in topology optimisation can lead to performance optimality while ensuring manufacturability of designs. Numerical techniques have been previously proposed to obtain support-free designs in AM, however, few works have verified the manufacturability of their solutions. Physical verification of manufacturability becomes more critical recalling that the conventional density-based topology optimisation methods will inevitably require post-processing to smooth the boundaries before sending the results to a 3D printer. This paper presents the smooth design of self-supporting topologies using the combination of a new Solid Isotropic Microstructure with Penalisation method (SIMP) developed based on elemental volume fractions and an existing AM filter. Manufacturability of selected simulation results are verified with Fused Deposition Modeling (FDM) technology. It is illustrated that the proposed method is able to generate convergent self-supporting topologies which are printable using FDM.

This paper introduces an innovative composite railway sleeper with an optimal material usage for a narrow-gauge railway track under static loading condition. The composite sleeper is designed using sandwich panels that were bonded and coated with epoxy polymer matrix. The sleeper’s optimized shape was obtained using topology optimization. The vertical deflection and sleeper-ballast contact pressure of the optimized sleeper were analyzed by finite-element simulation and compared with a traditional timber sleeper. Prototype sleepers were then manufactured and their performance was evaluated experimentally. Results showed that the optimal sleeper shape only needs 50% volume of materials required for a standard rectangular timber sleeper. The performance of the optimal sleeper satisfactorily met the Australian standard requirements and was very similar to a timber sleeper indicating the high potential of this sleeper technology to replace the existing timber sleepers. This new sleeper is currently being tested in the Queensland Rail network as part of their sleeper maintenance program.

Evaluation of numerical procedures to determine seismic response of structures under influence of soil-structure interaction soil-structure interaction;shaking table test;inelastic seismic response;equivalent linear method;fully nonlinear method;inelastic design procedure; In this study, the accuracy and reliability of fully nonlinear method against equivalent linear method for dynamic analysis of soil-structure interaction is investigated comparing the predicted results of both numerical procedures with the results of experimental shaking table tests. An enhanced numerical soil-structure model has been developed which treats the behaviour of the soil and the structure with equal rigour. The soil-structural model comprises a 15 storey structural model resting on a soft soil inside a laminar soil container. The structural model was analysed under three different conditions: (i) fixed base model performing conventional time history dynamic analysis, (ii) flexible base model (considering full soil-structure interaction) conducting equivalent linear dynamic analysis, and (iii) flexible base model performing fully nonlinear dynamic analysis. The results of the above mentioned three cases in terms of lateral storey deflections and inter-storey drifts are determined and compared with the experimental results of shaking table tests. Comparing the experimental results with the numerical analysis predictions, it is noted that equivalent linear method of dynamic analysis underestimates the inelastic seismic response of mid-rise moment resisting building frames resting on soft soils in comparison to the fully nonlinear dynamic analysis method. Thus, inelastic design procedure, using equivalent linear method, cannot adequately guarantee the structural safety for mid-rise building frames resting on soft soils. However, results obtained from the fully nonlinear method of analysis fit the experimental results reasonably well. Therefore, this method is recommended to be used by practicing engineers.

This paper aims to explore the effects of optimisation parameters (the filter radius, mesh size, and target volume fraction) on the compliance and manufacturability of smooth self-supporting topologies for additive manufacturing (AM); and conduct manufacturability experiments of selected simulation results with the Selective Laser Melting (SLM) technology. In this study, smooth self-supporting topologies are obtained with a combined method of the Solid Isotropic Microstructure with Penalization method (SIMP) with the smooth boundary representation and Langelaar's AM filter. Numerical examples illustrate that a higher filter radius can lead to simpler smooth self-supporting topologies, but curved top corners that violate the critical overhang angle of 45° are inevitably generated. Additionally, the mesh size is found to be not as an important factor as the filter radius in affecting the manufacturability and performance. As a result of the self-supporting constraint, a small volume fraction can easily result in structural discontinuity. The experimental results demonstrate that the self-supporting topologies obtained are all printable in SLM.