TOPOLOGY OPTIMIZATION OF LIGHTWEIGHT STRUCTURES WITH APPLICATION TO BONE SCAFFOLDS AND 3D PRINTED SHOES FOR DIABETICS

An automatic complex topology lightweight structure generation method (ACTLSGM) is presented to automatically generate 3D models of lightweight truss structures with a boundary surface of any shape. The core idea of the ACTLSGM is to use the PIMesh, a mesh generation algorithm developed by the authors, to generate node distributions inside the object representing the boundary surface of the target complex topology structures; raw lightweight truss structures are then generated based on the node distributions; the resulting lightweight truss structure is then created by adjusting the radius of the raw truss structures using an optimization algorithm based on finite element truss analysis. The finite element analysis-based optimization algorithm can ensure the resulting structures satisfy the design requirements on stress distributions or stiffness. Three demos, including a lightweight structure for a cantilever beam, a femur bone scaffold, and a 3D shoe sole model with adaptive stiffness that can be used to adjust foot pressure distributions for patients with diabetic foot problems, are generated to demonstrate the performance of the ACTLSGM. The ACTLSGM is not limited to generating 3D models of medical devices, but can be applied in many other fields, including 3D printing infills and other fields where customized lightweight structures are required.

DIGITAL FABRICATION AS A LEARNING MEDIA FOR LIGHTWEIGHT STRUCTURE WITH CASE STUDY OF SHELL STRUCTURE

The lightweight structure system is an effort to optimize the structure to distribute the load efficiently. Unfortunately, students often have difficulty imagining the learning outcomes application in the real world when studying light structural systems. However, the use of the scalar model can still explain several essential aspects of a lightweight structural system, one of which is the effect of connection and formation of material components on the structural capability. Therefore, this paper aims to bridge the learning process by utilizing digital devices from the concept stage of structural modeling with the help of software (Rhinoceros, Grasshopper, and Kangaroo) to the realization process using laser cutting. The method used is a semi-experimental method that applies Hooke's law principle, which produces a shell structure system with a digital fabrication approach that utilizes a lightweight material, namely, corrugated paper board, as the primary material. This paper concludes that digital technology and digital fabrication processes can help students understand the concept of lightweight structures because they can use computer simulations, cut them using laser cutting, and assemble them in the field in a series of simultaneous processes.

Standardization of Lightweight Structure Via Design One Build Many Solution

Petroliam Nasional Berhad (PETRONAS) is embarking on the implementation of the Design One Build Many (D1BM) concept, an integrated approach on design standardization, replication and volume consolidation for light weight fit for purpose wellhead platforms - also known as Lightweight Structure (LWS). The objective of the standardization is to enable monetization of marginal and small fields by improving project economics that are challenged with the high development costs and conventional execution schedules. Traditionally, projects are developed through a "bespoke" design which requires a specific engineering study during the Front End Loading (FEL) phase to cater for the field specific requirements. In addition, once the project has been sanctioned, it is a must to undergo tendering and bidding activities which can increase field monetization duration by four to five months. The current "bespoke" design has resulted in non-standardization, loss of opportunity for volume consolidation and ultimately longer time for field monetization. Although the Design One Build Many principles were known for a long time, but they were rather project oriented. Thus this emerging solution is a result of synthesizing multiple challenges with the goal to establish an end-to-end systematic approach in monetizing marginal and small fields by lowering development cost and monetization duration. There will be standardized sets of Base Design and a flexible Catalogue items to cater for standardized add on items. Lessons learned incorporation upon the repeated design and standardized execution strategy including Engineering, Procurement, Construction, Installation and Commissioning could also help in improving the delivery efficiency for the lightweight structure. The greater collaboration across fields and blocks will give significant added advantage through economies of scale efficiency and eventually increase in the overall project value.

Effective Point Cloud Analysis Using Multi-Scale Features

Fully exploring the correlation of local features and their spatial distribution in point clouds is essential for feature modeling. This paper, inspired by convolutional neural networks (CNNs), explores the relationship between local patterns and point coordinates from a novel perspective and proposes a lightweight structure based on multi-scale features and a two-step fusion strategy. Specifically, local features of multi-scales and their spatial distribution can be regarded as independent features corresponding to different levels of geometric significance, which are extracted by multiple parallel branches and then merged on multiple levels. In this way, the proposed model generates a shape-level representation that contains rich local characteristics and the spatial relationship between them. Moreover, with the shared multi-layer perceptrons (MLPs) as basic operators, the proposed structure is so concise that it converges rapidly, and so we introduce the snapshot ensemble to improve performance further. The model is evaluated on classification and part segmentation tasks. The experiments prove that our model achieves on-par or better performance than previous state-of-the-art (SOTA) methods.

Investigation of Energy-Absorbing Properties of a Bio-Inspired Structure

Numerous engineering applications require lightweight structures with excellent absorption capacity. The problem of obtaining such structures may be solved by nature and especially biological structures with such properties. The paper concerns an attempt to develop a new energy-absorbing material using a biomimetic approach. The lightweight structure investigated here is mimicking geometry of diatom shells, which are known to be optimized by nature in terms of the resistance to mechanical loading. The structures mimicking frustule of diatoms, retaining the similarity with the natural shell, were 3D printed and subjected to compression tests. As required, the bio-inspired structure deformed continuously with the increase in deformation force. Finite element analysis (FEA) was carried out to gain insight into the mechanism of damage of the samples mimicking diatoms shells. The experimental results showed a good agreement with the numerical results. The results are discussed in the context of further investigations which need to be conducted as well as possible applications in the energy absorbing structures.

Mechanical properties of ZEK100 Mg alloy

Low rare-earth containing magnesium (Mg) alloys are considered lightweight structure materials and are wildly used in automotive and aerospace industry. Tensile and fatigue behaviors are two important mechanical properties of metallic alloys. This research focused on the tensile and fatigue properties of ZEK100 Mg alloys. Microstructure of ZEK100 alloy contained equiaxed grains and exhibited relatively weaker texture compared with other RE-free Mg alloys. During tensile test, as the strain rate increased, yield stress, ultimate tensile strength and hardening capacity increased, but the elongation decreased. Strain rate was found to influence tensile properties of ZEK100 Mg alloy. The stress controlled fatigue test showed that as the stress ratio increased, the stress amplitude and the fatigue life both decreased. Fatigue crack was observed to initiate from specimen surface, and crack propagation was characterized by fatigue striations.

Mechanical properties of ZEK100 Mg alloy

Low rare-earth containing magnesium (Mg) alloys are considered lightweight structure materials and are wildly used in automotive and aerospace industry. Tensile and fatigue behaviors are two important mechanical properties of metallic alloys. This research focused on the tensile and fatigue properties of ZEK100 Mg alloys. Microstructure of ZEK100 alloy contained equiaxed grains and exhibited relatively weaker texture compared with other RE-free Mg alloys. During tensile test, as the strain rate increased, yield stress, ultimate tensile strength and hardening capacity increased, but the elongation decreased. Strain rate was found to influence tensile properties of ZEK100 Mg alloy. The stress controlled fatigue test showed that as the stress ratio increased, the stress amplitude and the fatigue life both decreased. Fatigue crack was observed to initiate from specimen surface, and crack propagation was characterized by fatigue striations.

Design of PEIS: A Low-Cost Pipe Inspector Robot

This paper outlines the design of a novel mechatronic system for semi-automatic inspection and white-water in-pipe obstruction removals without the need for destructive methods or specialized manpower. The device is characterized by a lightweight structure and high transportability. It is composed by a front, a rear and a central module that realize the worm-like locomotion of the robot with a specifically designed driving mechanism for the straight motion of the robot along the pipeline. The proposed mechatronic system is easily adaptable to pipes of various sizes. Each module is equipped with a motor that actuates three slider-crank-based mechanisms. The central module incorporates a length-varying mechanism that allows forward and backward locomotion. The device is equipped with specific low-cost sensors that allow an operator to monitor the device and locate an obstruction in real time. The movement of the device can be automatic or controlled manually by using a specific user-friendly control board and a laptop. Preliminary laboratory tests are reported to demonstrate the engineering feasibility and effectiveness of the proposed design, which is currently under patenting.