Additive Manufacturing In Construction Research Articles

AUTOMATIC GEOMETRIC INSPECTION IN DIGITAL FABRICATION

Abstract. Additive Manufacturing in construction allows to create complex objects of different materials. Accordingly, an appropriate co-registration and comparison between the printed object and its digital model is needed for several purposes: quality control (QC) to ensure that tolerances are maintained and the realisation of a digital twin which holds the actual geometry. In this paper, we introduce an automated robotic data capturing and direct co-registration method. That is, a terrestrial laser scanner (TLS) is mounted on a robot to be moved freely in the printing room. In addition, various strategies are employed for quality control. The scanner is also mounted on the tripods, to validate the accuracy of our data capturing and co-registration solution. Furthermore, the experiment on real data is conducted for two different objects: a shotcrete printed object and a wax material object. Our experiments revealed that there is almost no influence on the scanner position accuracy compared to classical setup (mounting the TLS on tripod). The scanner position accuracy when mounted on tripods is 0.76 mm and the accuracy achieved by mounting the scanner on the robot is 1.03 mm. From the simulation it is noticed that C2M cannot detect missing extruded parts. To cope this problem, we used C2C and M3C2 algorithms. For real data scenario, without edge trimming and surface finishing it is challenging to interpret the data directly. However, M3C2 provided better results but it requires parameters tuning. In case of the surface finished object C2M and M3C2 algorithms have almost similar results.

Reinforcement Strategies for Additive Manufacturing in Construction Based on Dynamic Fibre Winding: Concepts and Initial Case Studies

Whereas entire houses are reported to be built by means of 3D Concrete Printing (3DCP), automated integration of reinforcement is still a vastly unresolved challenge and - undoubtfully - a crucial requirement for widespread adoption of 3DCP in construction practice. The disruptive technology of 3DCP opens up the chance to overcome insufficiencies of conventional steel reinforcement and its rationalised orthogonal use. This paper discloses a field of options for future construction by exploring possible reinforcement strategies for different kinds of cement-based Additive Manufacturing techniques using continuous textile fibres. A methodology is introduced to identify, compare and assess new processes for integration of fibre reinforcement based on robotic winding. Two novel approaches will be described regarding Large Particle 3D Concrete Printing and Shotcrete 3d Printing. Respective case studies will be presented in order to give a basic proof of concept.

Contour Tracking Control for Mobile Robots applicable to Large-scale Assembly and Additive Manufacturing in Construction

In the construction industry, as well as during the assembly of large-scale components, the required workspaces usually cannot be served by a stationary robot. Instead, mobile robots are used to increase the accessible space. Here, the problem arises that the accuracy of such systems is not sufficient to meet the tolerance requirements of the components to be produced. Furthermore, there is an additional difficulty in the trajectory planning process since the exact dimensions of the pre-manufactured parts are unknown. Hence, existing static planning methods cannot be exerted on every application. Recent approaches present dynamic planning algorithms based on specific component characteristics. For example, the latest methods follow the contour by a force-controlled motion or detect features with a camera. However, in several applications such as welding or additive manufacturing in construction, no contact force is generated that could be controlled. Vision-based approaches are generally restricted by varying materials and lighting conditions, often found in large-scale construction. For these reasons, we propose a more robust approach without measuring contact forces, which, for example, applies to large-scale additive manufacturing. We based our algorithm on a high-precision 2D line laser, capable of detecting different feature contours regardless of material or lightning. The laser is mounted to the robot’s end-effector and provides a depth profile of the component’s surface. From this depth data, we determine the target contour and control the manipulator to follow it. Simultaneously we vary the robot’s speed to adjust the feed rate depending on the contour’s shape, maintaining a constant material application rate. As a proof of concept, we apply the algorithm to the additive manufacturing of two-layer linear structures made from spray PU foam. When making these structures, each layer must be positioned precisely on the previous layer to obtain a straight wall and prevent elastic buckling or plastic collapse. Initial experiments show improved layer alignment within 10 % of the layer width, as well as better layer height consistency and process reliability.

Camera-based Process Monitoring for Powder Bed Additive Manufacturing in Construction

The detection of defects in the production of large-scale components is very important for the productivity of a machine, especially in fow production facilities. An effective approach is proposed to automatically detect insufficient layers in the additive manufacturing process of sand formworks for the construction industry. For this a method is introduced to integrate a camera based quality control into the powder bed binder jetting process. Results show the possibility to reduce reject parts by comparing an image of the current layer geometry to the according CAD model.

Additive Manufacturing in Construction: the Research of the Anisotropy Concrete Strength Effect

Additive Manufacturing in Construction: the Research of the Anisotropy Concrete Strength Effect

Rheology and microstructure development of hydrating tricalcium silicate - implications for additive manufacturing in construction

Dielectric RheoSANS measurements are conducted on hydrating triclinic and monoclinic tricalcium silicate pastes with and without a sucrose admixture to simultaneously probe the changing microstructure by small angle neutron scattering (SANS), rheology, and electrical conductivity. The average total surface area of nanoscale calcium silicate hydrate (C-S-H), determined from fractal models fitted to SANS data, at the setting time is estimated to be (17.1(56)) m2 cm−3, independent of C-S-H polymorph or retardation of the hydration reactions. The growth rate of C-S-H with respect to the degree of hydration of the triclinic tricalcium phase is approximately 48 % less than the monoclinic tricalcium silicate phase, a result that may be attributed to the increased number of fine grains in the monoclinic C3S paste. Developing an understanding between the microstructural changes of cement paste and engineering material properties is a critical first step toward engineering cement phase compositions.

Printability of materials for extrusion 3D printing technologies: a review of material requirements and testin

One of the major challenges facing 3D printing for construction is the technological suitability, ‘printability’, of the materials used. These cement-based materials differ from those used in other sectors, which has a series of conditioning factors that are the object of the present analysis. This article first reviews the definition of the term ‘printability’ and its constituent stages. Those stages condition the requirements to be met by cement-based materials, whether designed for other uses or developed ad hoc, and therefore the tests applicable to determine their aptitude for use in additive manufacturing for construction. That is followed by a review of the standardised tests presently in place for mortars and concretes that can be used to verify a material’s compliance with such requirements. The paper concludes with a recommendation on the advisability of developing a standard test or suite of tests to ascertain printability.

Additive Manufacturing of Large Coreless Filament Wound Composite Elements for Building Construction.

Digitization and automation are essential tools to increase productivity and close significant added-value deficits in the building industry. Additive manufacturing (AM) is a process that promises to impact all aspects of building construction profoundly. Of special interest in AM is an in-depth understanding of material systems based on their isotropic or anisotropic properties. The presented research focuses on fiber-reinforced polymers, with anisotropic mechanical properties ideally suited for AM applications that include tailored structural reinforcement. This article presents a cyber-physical manufacturing process that enhances existing robotic coreless Filament Winding (FW) methods for glass and carbon fiber-reinforced polymers. Our main contribution is the complete characterization of a feedback-based, sensor-informed application for process monitoring and fabrication data acquisition and analysis. The proposed AM method is verified through the fabrication of a large-scale demonstrator. The main finding is that implementing AM in construction through cyber-physical robotic coreless FW leads to more autonomous prefabrication processes and unlocks upscaling potential. Overall, we conclude that material-system-aware communication and control are essential for the efficient automation and design of fiber-reinforced polymers in future construction.

TRR 277: Additive manufacturing in construction

AbstractThe building industry is one of the least digitalized sectors of the global economy to date. Unlike other industrial sectors, the manufacturing of buildings is characterized by traditional handicraft techniques and individualized construction processes. Digital production technologies from other industrial sectors have not become established in the construction industry because they do not allow the necessary individualization or are uneconomical to transfer to construction. The advantages of additive manufacturing (AM) technologies are that automation and individualization are not contradictory. Furthermore, a new design strategy is embedded in 3D printing, namely to build up material only where it is structurally or functionally needed. AM is, therefore, both economical and resource‐efficient. The DFG Collaborative Research Centre/Transregio TRR 277 Additive Manufacturing in Construction (AMC) of the two universities TU Braunschweig and TU Munich wants to research the technology of AM fundamentally and also contributes to the digitization of the construction industry. This article gives an overview of the goals, work programme, and methods of the TRR 277, as well as its three focus areas and 18 scientific research projects.

Additive manufacturing in construction: A review on technologies, processes, materials, and their applications of 3D and 4D printing

In this paper, the current state of the art of additive manufacturing (AM) in the construction industry to manufacture on large scales is reviewed. The central concept of AM was defined, and it has been highlighted in the large use in several sectors. The main advantages that AM offers in the construction industry were described with at the same time the most important challenges that need to be addressed for real use. The main AM technologies solutions on large scales were described from more compact solutions like gantry technology to more flexible and free technology solutions. The choice of an AM solution rather than another is closely linked to the materials to be used and the building component to be built. Regarding materials, the research focused on materials based on aggregates, metals, and polymers. The application of AM in the construction field requires more studies and further research.

Analysis of concrete strength determination methods for additive manufacturing

The property control of concrete mix and hardened concrete is an integral part of the construction process. With the development of additive manufacturing in construction, the methods of assessing the properties of concrete mix and concrete are characterized by the formation of their structure and properties in concrete laying and curing. Currently, there is no regulatory documentation on a reliable assessment of the concrete mix and concrete quality for additive manufacturing. The purpose of this work is to propose a method for determining the concrete strength for additive manufacturing. The proposed concrete mix composition matches the technological requirements for 3D printing equipment and possesses the required properties. The concrete strength analysis and research methods are carried out in accord with the Russian State Standard. The paper describes the main problems of the concrete quality control in using additive manufacturing and proposes methods for determining the concrete strength properties for 3D printing.

Applicability and integration of concrete additive manufacturing in construction industry: A case study

The spread of additive manufacturing in recent years has broadened the sector of applications, namely in the construction field. This technology enables new functionalities and opportunities to be considered for the construction industry. Indeed, 3D printing processes can directly or indirectly affect the concrete material. Besides the printing processes for concrete structures, there are other indirect uses of 3D concrete printing, such as the manufacture of molds and formwork. However, its integration raises new challenges. This paper is first devoted to the state-of-the-art regarding the use of additive manufacturing in construction through a bibliographical study and an overview of various experiences in different countries. Secondly, the opportunities of such technologies for the construction sector will be discussed. Then, the issues and challenges related to the applicability and integration of concrete additive manufacturing will be highlighted. Finally, a diagnosis of the applicability and integration of concrete additive manufacturing has been made by analyzing the results of a survey of Moroccan professionals. The objective is to raise and identify key factors for successful integration.

Approach to an optimized printing path for additive manufacturing in construction utilizing FEM modeling

Based on experiences with common additive manufacturing processes, the application in the construction industry opens up new design freedoms and cost-effective production of complex structures. However, the time-dependent yield strength of fresh concrete leads to deformations of underlying layers during the printing process, especially when using conventional path planning methods in combination with material extrusion or jetting methods. This paper presents a finite element model based approach to minimize the resulting deviations from the target geometry by iteratively adjusting the process parameters according to simulated deformations. To achieve more detailed modelling, the utilized finite element model is derived from the printing path instead of the CAD data.

CURRENT SURVEYING METHODS FOR THE INTEGRATION OF ADDITIVE MANUFACTURING IN THE CONSTRUCTION PROCESS

Abstract. The Technical University of Braunschweig (Brunswick) and Technical University of Munich were successful to establish a Collaborative Research Centre called “Additive Manufacturing in Construction (AMC) – The Challenge of Large Scale” starting from 2020 and funded by the German Research Foundation (DFG). The aim of this project is “to create the basic conditions for the introduction of additive manufacturing in construction, and thus to pave the way for the use of resource-efficient constructions with a high level of design freedom”. Surveying engineering (geodetic surveying, photogrammetry, laser scanning and GNSS) plays a major role in one of the sub-projects called “Integration of Additive Manufacturing in the Construction Process”. This paper aims at introducing the large scale AMC with the main focus on investigating the role of surveying engineering in this topic which will be a topic of high interest in the coming years in the digital fabrication within construction field. After a short introduction on additive manufacturing in construction, this paper will present the general aims and structure of the Collaborative Research Centre. Thereupon, the importance of geometric quality inspection and establishing and transferring different coordinate systems during the Additive Manufacturing (AM) construction steps (elements fabrication, installation and whole structure/building control) and the role of geodetic surveying, photogrammetry, laser scanning and GNSS will be outlined. This will be presented within a subproject called “C06: Integration of Additive Manufacturing in the Construction Process” and potentials and challenges for integrating surveying engineering in component and building level additive manufacturing in construction are mentioned.

A Comprehensive Review of Additive Manufacturing in Construction of Electrical Machines

Additive manufacturing (AM) has been undergoing dynamic development in recent years. The latest evolution of AM has been recognised as a key enabling technology in a wide range of applications, some of which include medical, aerospace and automotive industries. The use of AM opens new avenues for design solutions, otherwise challenging or impossible to realise when using more conventional techniques for manufacture. No- or low-material waste and high-flexibility are some of the attributes of modern AM. This expanded paper aims to provide an up to date overview of the existing examples of employing AM in construction of electrical machines. The paper reviews research and development work related to all integral components of an electrical machine assembly. These include active parts like coils/windings, electrical insulation, stator/rotor magnetic core packs, permanent magnets (PMs). The machine structural/mechanical and thermal management components are also discussed in the paper. Further to these, the authors make some comments/forecasts on how the AM could improve performance and manufacturability of the future electrical machines.

Experimental Approach for Printability Assessment: Toward a Practical Decision-Making Framework of Printability for Cementitious Materials

The objective of this paper is to propose a pre-experimental framework of printability pre-assessment of cementitious materials. This study firstly presents a general review of additive manufacturing in construction and then examines the main characteristic of the material formulation and printability properties based on extrusion technique. This framework comes with experimental tests to determine a qualitative printability index of mixtures. It uses mix-designs reported in the literature to define interval ratio of mixture design to be investigated in this study. The focus was put on two criteria that influence the formulation namely flowability and buildability. Two practiced based tests, mini slump and cone penetrometer, were used to draw the flowability and buildability dimensionless index. The results were analyzed by introducing an optimal printability coefficient and examining their time evolution. An optimal time of printing was determined Toptimal. Finally, a 3D mortar printing system and its operational process are presented. Then, based on the measurement, the optimal mixture is identified and printed in a large-scale geometry.

Prospective study on the integration of additive manufacturing to building industry—Case of a French construction company

The objective of this paper is to present a reflection on the use of Additive manufacturing in construction. In this research examples from manufacturing industries are presented. Some Advantages of additive manufacturing in industry were identified. Relevant cases used to promote AM for construction are: building rate improvement and schedules shortening. This study investigated these advantages in three parts. Firstly, a comparison between construction and manufacturing industry was presented. Secondly, Design and Building rate for construction were studied using data from a French construction company. Finally a comparison was made between conventional processes and Additive manufacturing. Conventional processes included prefabrication and casting on site. Results showed that pre-casting may be faster than AM in some cases. Time saving is not necessary the best advantage from applying additive manufacturing to construction.

Developments in construction-scale additive manufacturing processes

Additive manufacturing in construction is beginning to move from an architect's modelling tool to delivering full-scale architectural components and elements of buildings such as walls and facades. This paper discusses large-scale additive manufacturing processes that have been applied in the construction and architecture arena and focuses on ‘Concrete Printing’, an automated extrusion based process. The wet properties of the material are critical to the success of manufacture and a number of new criteria have been developed to classify these process specific parameters. These criteria are introduced and key challenges that face construction scale additive manufacturing are presented.