Multi-axis Hybrid Research Articles

Base shape generation and optimization for multi-axis hybrid additive manufacturing

Hybrid additive manufacturing (HAM) processes combine the advantages of both additive and non-AM processing to achieve an improvement on quality, cost, and a good quality-cost balance. The non-additive manufacturing process is able to build the physical component of a computer-aided design model from zero or an existing relatively simple subvolume, called base shape in this paper. Hence, if the processing start point is an existing subvolume, how to determine an optimal base shape to save printing time, avoid manufacturing constraints and ensure component quality is an open question in the process planning. Nevertheless, this topic has rarely been investigated. Therefore, in this paper, we propose an optimization method using model skeleton-based decomposition and evolutionary computation. A set of generic evaluation criteria are defined for alternative evaluation. We also present two case studies in this paper for validating the proposed method and conclude that sequential HAM processes have a wide application potential.

Design and Analysis of a Desktop Multi-Axis Hybrid Milling-Filament Extrusion CNC Machine Tool for Non-Metallic Materials

Hybrid Manufacturing technologies enable the manufacturability and high manufacturing efficiency of innovative part designs comprising high complexity features which could not otherwise be manufactured in a single or a small number of steps. This study proposes the design of an industrial-grade low-cost fully automated multi-axis hybrid Additive and Subtractive CNC machine for non-metallic parts. It combines operations of a six-axis CNC machining center with a six-axis extrusion 3D printer with automated tool head change for processing parts made of polymer and special 3D printing materials (e.g., carbon fiber reinforced filaments). The design process includes static, dynamic and harmonic response Finite Element Analysis to optimize its structural strength and at the same time to reduce machine component costs down to a few thousand euros for all included components and subsystems, thus making it viable for industrial purposes. In investigated loading scenarios, analysis results show that at the brim of a 200 mm diameter round machine table, even at its most unfavorable angular positions, maximum deformation was no more than 0.24 mm, with a factor of safety in the magnitude of 10 to 20 while applying cutting force profiles with amplitudes up to 100 N, which exceedingly satisfies structural specifications for the proposed machine design operation.

Multiaxis Hybrid Simulation of Collapse Resistant Buildings with Ductile Soft Story Formed by Concrete-Filled Steel Tube Columns

A widespread problem in regions of low to moderate seismicity is the failure of buildings with soft-story collapse mechanisms. A reliable approach to improve the design of such buildings is to use concrete-filled steel tube (CFT) columns to form a ‘ductile’ soft story to arrest damage at the first level. This can perform as an isolator to limit the damage and prevent it from spreading to the rest of the building. In this paper, the multiaxis hybrid simulation method is used to evaluate the three-dimensional response of CFT columns while they serve as part of a building developing ductile soft first story mechanism. For this purpose, the multiaxis substructure testing (MAST) system at Swinburne University of Technology was utilized to simulate realistically the time-varying multi-directional boundary forces generated by ground motions on the CFT columns. The circular and square cross-section shapes as the most popular type of CFTs were tested and the damage progression, global hysteretic behavior, and deteriorating mechanisms were studied. The obtained data were then used to conduct a fragility analysis to compute the risk of collapse. The results highlight the excellent performance of CFTs and their potential to construct low-damage collapse resistant buildings.

Multi-Station Multi-Axis Hybrid Layered Manufacturing (MSMA-HLM)

Additive manufacturing is advanced manufacturing technology in which material is added layer by layer. The hybrid approach with conventional and additive processes is utilized for making the component faster and cost-effective. Hybrid Layered Manufacturing (HLM) is the process in which a 3D component is made by adding and subtracting material layer by layer. HLM is basically for a metallic component in which material is added by depositing metal in wire form through an arc, LASER, EBM, and a small amount of material is removed by machining and thus making the system hybrid. There are various levels of hybridization in terms of approach, material, layering, joining process, kinematics and operations. A complete setup of HLM is developed with multiple stations and with a simultaneous five-axis system named as Multi-Station Multi-Axis Hybrid layered Manufacturing (MSMA-HLM). MSMA-HLM has its application in aerospace, automobile, marine, medical, etc. The various case studies with the HLM process are also demonstrated in this paper with cost and time compared with conventional manufacturing. The need for multiple stations during the HLM process is explained in this paper. The preheating, hammering, and inspection units are the add-ons in the manufacturing process for making defect-free components.

Development and application of multi-axis hybrid simulation for seismic stability of steel braced frames

This paper presents the development and application of multi-axis pseudo-dynamic hybrid simulation for evaluating the seismic stability of steel braced frame structures. The advanced hybrid testing system used to perform hybrid simulation is first described, followed by the development of hybrid simulation and main challenges, namely the friction forces generated in the testing system and high-frequency noise in force feedback signals. The strategies proposed to overcome these challenges are then described. Two pseudo-dynamic hybrid simulations consisting of a two-tiered concentrically braced frame where a full-scale wide-flange column part of the frame is physically tested while the rest of the frame is numerically analysed are finally presented. The test results serve to verify the hybrid simulation technique, evaluate experimentally the seismic stability response of columns of steel multi-tiered concentrically braced frames and validate the findings of past fibre-based numerical models used to assess the seismic response of multi-tiered braced frames.

Multi-axial hybrid fire testing based on dynamic relaxation

This technical note presents the experimental validation of a hybrid fire testing coordination algorithm recently developed by some of the authors. For the first time, the algorithm is applied to solve the static response of a multiple-degrees-of-freedom hybrid model.

Modal Analysis of 3D Multi-axial Hybrid Composite with Experimental and Numerical Methods

Modal Analysis of 3D Multi-axial Hybrid Composite with Experimental and Numerical Methods

Hybrid simulation of bridges constructed with concrete-filled steel tube columns subjected to horizontal and vertical ground motions

This paper presents the application of multi-axis hybrid simulation for evaluating the seismic response of a rigid-frame bridge structure constructed with concrete-filled steel tube (CFST) columns subjected to combined horizontal and vertical ground motions. These types of bridges are believed to have superior seismic performance and better ability to withstand collapse when subjected to extreme multi-directional seismic loads. The case-study hybrid model was a 1:3 scaled bridge structure with three spans and double-column bents. The experimental element consisted of one CFST column while the rest of the bridge elements were modelled numerically in the computer. Two popular cross-section shapes of circular and square CFST columns were tested and compared. The structure was subjected to the horizontal (longitudinal) and vertical components of the Northridge ground motion with five increasing intensity levels to cover all scenarios ranging from frequent to very rare events during the lifecycle of the structure. A state-of-the-art hybrid testing facility, referred to as the multi axis substructure testing system, was used to simulate complex boundary effects on the physical specimen using mixed load/deformation modes. The bridge columns showed great levels of ductility and no sign of severe damage or loss of stability, while they were subjected to large axial force variations and lateral deformation demands during hybrid simulations. The superior seismic performance of CFST elements highlights their benefit in construction of more resilient bridges, particularly those with the vital roles in post-disaster operations.

Linking seismic resilience into sustainability assessment of limited-ductility RC buildings

While sustainability addresses the economic, social and environmental impacts distributed over the life cycle of a structure; commonly, ordinary events such as construction, normal operation and ageing are considered and the resilience of the structure to extreme events (natural disasters and man-made hazards) is often ignored. This study aims to introduce a framework to systematically integrate seismic-resilience into sustainability assessment of structures/infrastructures. A case study of a multi-story limited-ductility reinforced-concrete (RC) building with soft-story collapse mechanism is presented. This mode of failure is often expected in regions of low to moderate seismicity, where the detailing is poor. A numerical model is constructed based on the results of a number of multi-axis hybrid simulations allowing to realistically capture the three-dimensional response and the damage states of the RC building first-story columns from linear-elastic range to collapse. In addition, the application of carbon-fiber reinforced polymers (CFRP) as a cost-effective and rapid repair strategy in restoring the building columns is studied. The CFRP repair is proposed as an alternative to the demolition of the full building when subjected to large deformations; thereby, significantly enhancing post-disaster reparability and resilience of the structure. The developed numerical models are then used to quantify the sustainability metrics including repair cost, repair downtime and repair environmental impacts. These metrics are quantified by consecutive hazard, structural response, damage state, and recovery loss analyses in accordance to the PEER PBEE methodology. The results are then used to quantify the resilience parameters, including loss of performance and recovery, using the probabilistic resilience-based earthquake engineering (RBEE) approach.

Simulator of an additive and subtractive type of hybrid manufacturing system

Additive Manufacturing (AM) facilitates the production of intricate objects despite its weakness in attainable part quality and fabrication speed compared to the conventional manufacturing methods. To alleviate the problems arising as a natural outcome of AM methods, hybrid technologies become viable options by employing concurrent manufacturing procedures, e.g. synergetic additive and subtractive manufacturing (SM) actions. Hybrid workstations have recently opened up new dimensions to 3D-printing industry, but related research topics remain underexplored in the literature. In this study, a hybrid manufacturing simulator that imitates AM and SM operations is presented. The hybrid simulator reported aims to provide users with a comprehensive interpretation of the G-codes, thereby previews the AM/SM tool paths and the eventual shape of the fabricated object. Consequently, the simulator lets users realize the final form of the artifacts besides enabling them to notice possible problems on the manufacturing trajectories. In addition, a post-processor customized for multi-axis hybrid platforms is built for the generation of G-code files. As a significant feature of the proposed manufacturing simulator, the capability to handle variable bead-width on the additive infill path has also been addressed in the study.

An experimental study on cyclic behavior of aerated concrete block masonry walls retrofitted with different methods

Due to the insufficiency of the ductility, stability and low tensile stress capacity of the masonry shear walls responsible for carrying lateral loads, traditional brickwork masonry structures considered to be designed only under vertical service loads have been badly affected by the past severe earthquakes. The vulnerability of the existing masonry buildings can be decreased considerably by employing efficient retrofitting methods. This research work primarily aims to investigate experimentally cyclic behavior of aerated concrete block masonry walls before and after application of a special fiber retrofitting system. The investigated retrofitting system consists of multi-axial hybrid fabric made of alkali resistant glass polypropylene fibers for earthquake protection and white cement based plaster mortar with natural hydraulic lime. Another type of mortar with different material content was also tested to assess the adherence effect to the seismic retrofitting textile. The experimental results of this study were given with respect to force-displacement curves comparatively for all considered test specimens. It is concluded that the strength and the ductility capacity increased considerably by applying of the seismic textile, especially for two-sided retrofitting application with expanded glass granular made plastering.

In-Plane Strengthening of Clay Brick and Block Masonry Walls Using Textile-Reinforced Mortar

This study evaluates the use of a composite material composed of multiaxial hybrid glass-fibers and polypropylene fabric coated in a hydraulic lime-based mortar (referred to as textile-reinforced mortar) to improve the in-plane shear strength and displacement capacity of solid clay-brick and hollow clay-block masonry walls with the aim of defining a comprehensive test protocol. Design parameters of the adopted strengthening system are investigated, and both single-sided and double-sided configurations for application on wall surfaces are considered. The influence of the presence of an external thermal insulation layer on walls’ in-plane performance is also considered. The first stage characterizes the materials, their bonding properties, and the initial shear strength of the masonry bed-joints. The second stage investigates the in-plane behavior of strengthened masonry wall panels using diagonal compression testing. No premature debonding is observed, even with no mechanical anchorage between the masonry substrate and the strengthening layer. Out-of-plane deformation due to structural asymmetry is observed in the single-sided strengthening configuration.

A new method for locating candidate substrates for multi axis hybrid manufacturing systems

PurposeThis study aims to introduce a new method for locating candidate substrates in part models and evaluating their feasibility.Design/methodology/approachSlices of an STL model along candidate directions are evaluated for the fitting of regular cylindrical and rectangular stock. Next, the part model is skeletonized and tested for collision assuming deposition growth of features from the candidate substrate.FindingsThe method is successfully able to find feasible substrates and conduct collision simulation for a variety of part models.Research limitations/implicationsThe algorithm is limited to cylindrical and rectangular substrates and only considers collision between the substrate and the deposition head.Originality/valueThis method represents a new approach to solving a portion of the hybrid manufacturing process planning problem.

Small-scale multi-axial hybrid simulation of a shear-critical reinforced concrete frame

This study presents a numerical multi-scale simulation framework which is extended to accommodate hybrid simulation (numerical-experimental integration). The framework is enhanced with a standardized data exchange format and connected to a generalized controller interface program which facilitates communication with various types of laboratory equipment and testing configurations. A small-scale experimental program was conducted using a six degree-of-freedom hydraulic testing equipment to verify the proposed framework and provide additional data for small-scale testing of shearcritical reinforced concrete structures. The specimens were tested in a multi-axial hybrid simulation manner under a reversed cyclic loading condition simulating earthquake forces. The physical models were 1/3.23-scale representations of a beam and two columns. A mixed-type modelling technique was employed to analyze the remainder of the structures. The hybrid simulation results were compared against those obtained from a large-scale test and finite element analyses. The study found that if precautions are taken in preparing model materials and if the shear-related mechanisms are accurately considered in the numerical model, small-scale hybrid simulations can adequately simulate the behaviour of shear-critical structures. Although the findings of the study are promising, to draw general conclusions additional test data are required.

Optimized sequence planning for multi-axis hybrid machining of complex geometries

The emerging hybrid machining platform potentiates the manufacturing of complex structures that are previously unmachinable solely by subtractive machining. The essence of such a platform is the alternation incorporating both additive and subtractive process. Multiple alternations are needed to eventually produce a complex model. The planning of the build-up height in each alternation plays a crucial role in the overall process: a large build-up height of partial construction may block the cutter from accessing the in-process part; conversely, frequent alternations will degrade the overall efficiency as well as the surface finish. In order to find a perfect balance, a metric called machinability is proposed to evaluate the subtractive machining feasibility. An efficient algorithm for calculating the machinability under the dynamic obstacle growing environment is then developed accordingly. Based on that, an efficient and deterministic TOP-DOWN_SEQUENTIAL_MAXIMIZATION algorithm is presented that is able to minimize the number of alternations while at the same time ensuring a smooth tool path for each subtractive operation. Ample computer simulation examples are given to illustrate the effectiveness of the proposed methodology.

Collapse Assessment of Reinforced Concrete Building Columns through Multi-Axis Hybrid Simulation

Collapse Assessment of Reinforced Concrete Building Columns through Multi-Axis Hybrid Simulation

A process planning strategy for multi-axis hybrid manufacturing process

This paper outlines a process planning strategy for a multi-axis hybrid manufacturing process that includes a metal deposition system and a multi-axis CNC machining system to rapidly manufacture precision metal parts. Different from the current layered manufacturing processes of which build direction is fixed throughout the process, the orientation of the part can affect the non-support buildability in the multi-axis hybrid manufacturing process. However, each orientation that satisfies the buildability and other constraints may not be unique. In this case, the final optimal orientation is determined based on build time. The build time computation algorithm for multi-axis hybrid system is presented in this paper. To speed up the exhaustive search for the optimal orientation, a multi-stage algorithm is developed to reduce the search space. A case study is used as an example to show the process planning strategy.

Integrated Process Planning for a Multiaxis Hybrid Manufacturing System

A hybrid manufacturing system integrates computer numerical controlled (CNC) machining process and layered deposition process and achieves the benefits of both processes. An integrated process planning framework, which includes every module of the hybrid manufacturing process is critical for making the building of functional parts feasible and reliable. In this paper, the hybrid manufacturing system is introduced and the integrated process planning framework, which aims to automate the hybrid manufacturing is investigated. Critical components of the process planning, including decomposition of the computer-aided design (CAD) model, improvement of the toolpath generation pattern, and collision detection algorithms, are discussed. The interfacing and integrating process between deposition and surface finish machining is also studied. The goal of integrated process planning is to realize the automatic hybrid manufacturing process without much human interference. Experiments are implemented to validate the feasibility and reliability of the integrated process planning framework.

Automatic Process Planning and Toolpath Generation of a Multiaxis Hybrid Manufacturing System

With the integration of multiaxis layered manufacturing and material removal (machining) processes, a hybrid system has more capability and flexibility to build complicated geometry with a single setup. Process planning to integrate the two different processes is a key issue. In this paper, an algorithm of adaptive slicing for a five-axis Laser Aided Manufacturing Process (LAMP) is summarized that can generate uniform and non-uniform thickness slices. A method to build a non-uniform (thickness) layer that utilizes two processes is presented, and an overall algorithm for integration is described. The newly developed algorithm implemented in the process planning helps the hybrid system build parts more efficiently.