Theses

This section provides information on ongoing and completed master and doctoral theses.

Masters Theses

Concrete Additive Manufacturing System Design for Earth and Mars

Abstract: This work explores additive manufacturing of concrete using a six-axis robotic arm and its use in large scale, autonomous concrete construction. Concrete additive manufacturing uses an extrusion method to deposit concrete beads in layers to create a three-dimensional shape. This method of construction has been found to have many uses and advantages in both terrestrial and extraterrestrial applications. The lack of formwork and the autonomous nature of this manufacturing method allows for new geometries and materials to be printed where it may not be safe for humans to go. Autonomous construction has been suggested as a method of creating habitats for humans on Mars and on the moon using in-situ materials. This thesis presents research towards systems that could be used on the surface of Mars as well as on Earth, which required increasing the capabilities of a six-axis robotic arm along with overcoming system challenges to achieve deliverables for the NASA’s “3D Printed Habitat Challenge”. The system designed increased the build volume, integrated embedding, printed non-coplanar sections, and addressed issues with continuous extrusion and implications of toolpaths that minimized travel moves. The system was demonstrated by printing a one-third-scale Martian habitat for which the team printed the first fully enclosed structure at an architectural scale without the use of support.

Author: Nate Watson

Committee: Sven Bilén, Nicholas Meisel

Program: Master of Science in Additive Manufacturing and Design

Structural Consideration in Additive Manufacturing of Concrete as Part of Nasa’s Centennial 3D Printed Mars Habitat Challenge

Abstract: Additive Manufacturing (AM) method used for printing concrete offers potential improvement in conventional building construction. Numerous benefits of AM of Concrete (AMoC), such as less material waste, low labor demand, and ability to mass-customize for aesthetic purposes, allow the design flexibility combined with efficient manufacturing and lower cost for concrete construction compared to traditional methods. However, as much as AM has great potential, there is also a lot of demand for refining AM technology for practical application to concrete construction. The development of a 3D printer system for AMoC requires comprehensive and exhaustive study covering interdisciplinary areas.

This study considered the structural engineering aspect of using AMoC for 3D printing of habitat on Mars according to guidelines specified in NASA’s 3D Printed Habitat Challenge for Mars. This thesis reflects one aspect of a Penn State research team that participated in the NASA’s 3D printed habitat competition, and that has been developing and deploying an AMoC system and experimenting using three different printable mixtures and operating a 3D concrete printer system for academic study and practical application. The research presented in this thesis focused on studying the structural aspects of printing a series of components as part of the habitat design development. The study helped to evaluate the possibility of 3D printed habitat’s structural integrity under the Mars’ surface environment. Furthermore, the study provided some lessons based on observations of printing and testing printed components. For example, the study provides some understanding related to existing anisotropy in mechanical properties, degraded structural performance in comparison to cast concrete parts, varying printability and structural performance of different printable concretes, possibility and limitation of 3D printed Mars habitat, and possible improvement of AMoC based on the challenges from the research experience.

Author: Keunhyoung Park

Committee: Ali M. Memari, Aleksandra Radlinska, Jose Pinto Duarte, Sez Atamturktur

Program: Master of Science in Architectural Engineering

Development of a Straw-reinforced Clay-Based Mixture for 3D Printing Construction of Affordable Homes 

Abstract: 3D printing of cementitious material can provide an affordable, sustainable and optimized approach and opportunity for construction of homes in a short period of time, without compromising quality, craftsmanship, or customization. 3D printing of concrete structures results in higher precision, safer working conditions, faster construction speed, and lower costs of construction (avoiding the costs associated with formwork and labor). While most of the current R&D efforts in this field are focused on cement-based concrete printing, this research has focused on design and development of a sustainable clay-based mixture design that mainly includes clay, sand, straw, lime, and water. This allows a truly affordable home construction system for underprivileged areas and societies. The goal of this project is to design a mixture that will be printable for a tiny house construction. The specific objective of the current project is to demonstrate printability of such a mixture design and buildability of structural components with sufficient strength. This thesis will provide a review of the current state of the art in clay-based traditional construction such as cob and adobe homes, and then transitioning to 3D printing construction. The thesis will describe typical mixture designs for such construction and describe the challenges in going from lab-scale research to actual tiny home and small home construction. In particular, because of the low tensile capacity of clay-based mixture even with straw reinforcement, the study will illustrate how curved shapes can reduce the tensile stresses and how gravity loads can be resisted through compressive stresses. Typical conceptual designs based on domed shape homes will be presented.

Author: Amnah Alqenaee

Committee: Ali Memari (advisor), José P. Duarte, Aleksandra Radlińska

Program: Master of Science in Civil Engineering with a minor in Architectural Engineering

Automation of additive manufacturing of concrete structures through closed-loop control of printing equipment.

Abstract: The focus of my research since fall 2019 has been the development of both software and hardware for better integration and automation of the various equipment used in additive manufacturing of concrete structures. Unlike desktop or industrial 3D printers which are developed from the ground up, additive manufacturing using concrete as the main building material usually requires bringing together both industrial robots and conventional construction equipment. Hence, additional research and development are required for these systems to effectively communicate with each other and function as a single system. 

To achieve this, a control panel was developed to facilitate communication between these components of the printing system. The control panel mainly consists of a microcontroller that can be programmed to automatically control key components of the printing system such as the industrial robotic arm and the concrete mixer. Furthermore, the control panel also makes it possible for an operator to remotely monitor and control printing jobs from the main computer. Communication between the control panel and the main computer is facilitated by Grasshopper in Rhino.

Author: Daniel Henneh

Committee: Dr. Sven Bilen, Dr.Nicholas Meisel

Program: Engineering Design

Doctoral Theses

Automated multi-material fabrication of buildings

Abstract: Architects and engineers are under increasing pressure to improve the efficiency and effectiveness of the architecture, engineering and construction (AEC) sector, reducing environmental impacts, material use and costs. The integration of digital technologies into construction processes will allow for a greater flexibility in design and customization, as well the emergence of complex shapes and new materials. In recent years, the interest in developing additive manufacturing (AM) technologies in the AEC has increased, though traditional AM technologies are limited to the design and fabrication of physical components with homogeneous material properties, assuring structural safety but with no efficient use of material resources. To overcome these limitations, an AM system was developed for automated fabrication, enabling the fabrication of heterogeneous composite materials with varying material distribution, simulating nature’s structural behavior. The aim is to design and fabricate functionally graded building components with increased performance. 

Author: Flávio Craveiro

Committee: José Duarte (advisor), Paulo Bártolo, Helena Bártolo.

Program: PhD in Architecture, Faculty of Architecture, University of Lisbon

Experimental Prediction of Material Deformation and Toolpath Design Compensation in Large-Scale Additive Manufacturing of Concrete

Abstract: Additive manufacturing (AM) of cementitious materials has become a popular subject over the last decade. Development of this technology requires modeling the complex relationships between printing materials, printing systems, and printable designs. This model is essential to successfully print concrete structures. One of the important aspects of a research in this area is to find a concrete material with adequate rheological, hardening, and strength properties for printing architectural structures. Further, since the properties of fresh and hardened concrete and its deformation behavior affect the shape accuracy of the printed geometries, it requires designers to adjust the toolpaths and technology to account for this issue. This research is comprised of two main parts.First, modeling the deformation of printed concrete beads and second, developing an adequate toolpath design method for 3D printing concrete using a generative design system, which develops algorithms for decomposing complex geometries into simpler ones.

Author: Negar Ashrafi

Committee: José Duarte (advisor), Shadi Nazarian, Sven Bilen, Ali Memari, Nick Meisel

Program: PhD in Architecture, Department of Architecture, College of Arts and Architecture

Multidisciplinary concurrent optimization framework for multi-phase building design process

Abstract: Design of buildings and infrastructure is becoming a complex multidisciplinary problem involving coupled systems such as architectural, structural, mechanical, electrical and plumbing systems dealt by multiple stakeholders. Such multidisciplinary design problems require modeling and analyzing multiple building design configurations for concurrent optimization of all systems. Further, modern day construction techniques such as robotic construction require the design to be vetted for manufacturability or constructability constraints in addition to other environmental, economic and technical performance objectives of the building design. This requires the usage of advanced tools such as parametric modeling for generation of large sets of design, fast and efficient methods for Multiphysics analysis and optimization and 4D simulation tools to test the sequence of construction. However, most of these tools and methods are fragmented in the AEC field and lack the capability to support multidisciplinary optimization across multiple building design phases. This thesis proposes a novel BIM based framework that utilizes a combination of advanced modeling, analysis and machine learning based surrogate models that enable multidisciplinary optimization across multiple design phases. Additionally, a common data exchange platform facilitating information exchange between the parametric algorithm, analysis tools, 4D-simulation tools, and optimization routines was also developed. The framework was demonstrated by using it to design a 3D Printable Mars habitat satisfying environmental, structural and robotic constructability objectives as part of the final round of the NASA Centennial Challenge.

Author: Naveen Kumar Muthumanickam

Committee: Dr. Timothy Simpson, Dr. Jose Duarte, Lisa Domenica Iulo, Dr. Loukas Kalisperis, Dr. Gordon Warn

Program: PhD in Architecture, Department of Architecture, College of Arts and Architecture

Design for Printability and Structural Integrity of 3D Printed Concrete Structures

Abstract: According to current data, 900 million people live in informal settlements with incipient basic infrastructure and degraded living conditions today and this number will double before 2030. To solve the shortage of affordable housing, it is necessary to develop innovative construction techniques that can overcome current inefficiencies of the construction industry, while decreasing its ecological footprint. The incorporation of additive manufacturing, or 3D printing, in the construction industry is a viable strategy for addressing the lack of productivity, as well as the energy and construction waste problems and, therefore, adequate for producing affordable housing. Despite its potential to change the way we build, challenges remain regarding the proper implementation for 3D printing using full-scale building materials. A common challenge is to predict whether a structure will collapse or not during printing, which requires the understanding of the material properties in the printing timeframe. 

This research will be divided into four main steps. First, desirable forms under compression are determined and strategies to obtain them are discussed. Then, material properties as a function of time are evaluated, which include yield stress, compressive strength, Young’s modulus and Flexural strength. After gathering information on these properties, the modes of failure and further structural behavior can be modeled with Finite element modeling and help of  constrained optimization methods. This way, it is possible to predict when the structure will collapse during printing. This model runs in parallel with a Toolpath optimization algorithm that adapts the toolpath depending on the region expected to collapse, by generating the appropriate printing pattern and layer orientation. Finally, a framework is proposed to help engineers in designing 3D printing structures according to printability constraints and early-age structural behavior. This framework is validated by case studies focused on vaulted structures for housing.

Author: Gonçalo Duarte

Committee: Dr. José Duarte (advisor, Architectural Engineering, Architecture), Dr. Ali Memari (Architectural Engineering), Dr. Nate Brown (Architectural Engineering), Dr. Nick Meisel (Engineering Design), Dr. Juan Pablo Guevaudan (Architectural Engineering)

Program: PhD in Architectural Engineering, Department of Architectural Engineering, College of Engineering

Development of Reinforcement Strategies for 3D Printed Concrete Structures

Abstract: Over the past two decades, efforts have targeted the introduction of 3D Printing of Concrete in building construction. Although numerous benefits can be achieved by using this technology in concrete construction (e.g., design freedom, time-saving, less labor work, no formwork cost), the lack of suitable reinforcement for printed concrete is the main obstruction to widely apply this technology. The main objective of this project is to develop new reinforcement methods that can be easily applied to different shapes of concrete elements (e.g., curved walls) and can provide promising improvement of mechanical properties to printed concrete. At the end of this project, the expected outcome of this research is a) new developed innovative reinforcement methods that overcome the shortcomings of the existing reinforcement methods, b) mechanical test results for printed concrete reinforced by the proposed innovative reinforcement methods, c) modified equations for calculating mechanical properties of printed concrete, d) Finite Element model for predicting structural behavior of printed concrete under loading conditions, and e) a printed scale-down model (tiny house) for exhibition.

Author: Zhengyu Wu

Committee: Dr. Ali Memari (Advisor, Architectural Engineering), Dr. José Duarte (Co-advisor, Architecture), Dr. Nathan Brown (Architectural Engineering), Dr. Nicholas Meisel (Engineering Design)

Program: PhD in Structural, Department of Architectural Engineering, College of Engineering