Hybrid deposition additive manufacturing: novel volume distribution, thermo-mechanical characterization, and image analysis

(c) The Author/sCAUL read and publish agreement 2022The structural integrity of additive manufacturing structures is a pronounced challenge considering the voids and weak layer-to-layer adhesion. One of the potential ways is hybrid deposition manufacturing (HDM) that includes fused filament fabrication (FFF) with the conventional filling process, also known as “HDM composites". HDM is a potential technique for improving structural stability by replacing the thermoplastic void structure with a voidless epoxy. However, the literature lacks investigation of FFF/epoxy HDM-based composites regarding optimal volume distribution, effects of brittle and ductile FFF materials, and fractographic analysis. This research presents the effects of range of volume distributions (10–90%) between FFF and epoxy system for tensile, flexure, and compressive characterization. Volume distribution in tensile and flexure samples is achieved using printable wall thickness, slot width, and maximum width. For compression, the printable wall thickness, slot diameter, and external diameter are considered. Polylactic acid and acrylonitrile butadiene styrene are used to analyze the brittle and ductile FFF structures. The research reports novel application of image analysis during mechanical characterization using high-quality camera and fractographic analysis using scanning electron microscopy (SEM). The results present surprising high tensile strain (0.038 mm/mm) and compressive strength (64.5 MPa) for lower FDM-percentages (10%, 20%) that are explained using in situ image analysis, SEM, stress–strain simulations, and dynamic mechanical analysis (DMA). In this regard, the proposed work holds novelty to apply DMA for HDM. The optimal volume distributions of 70% and 80% alongside fractographic mechanisms for lower percentages (10%, 20%) can potentially contribute to structural applications and future material-based innovations for HDM.fals

Improving the Mechanical Performance of 3D Printed Parts Using Fused Filament Fabrication

The 3D printing industry has seen rapid growth in the last 10 years and has been called the next industrial revolution. There are several different processes used in 3D printing, but the most popular process is called Fused Filament Fabrication (FFF) or Fused Deposition Modeling (FDM). This is the process where (most commonly) plastic filament enters a nozzle, is heated to a semi-liquid state, and then deposited into a pattern to create a print. One major drawback to this process is that the prints are anisotropic. This means that the strength of the print varies with the orientation that it was created. This project experimented to determine if a proposed post processing method would decrease the anisotropy in the FFF process. The proposed process involved using a high intensity lamp to flash the print after each layer is printed. The theory was that this would decrease the gap between deposited filaments and from research this was a proven way to make prints stronger. For this project, a Xenon Sinteron 2000 was used as the high intensity lamp and a Printrbot Simple Metal Plus was used as the 3D printer. Three experiments were done to determine if the Sinteron would be successful in reducing the gap between deposited filaments. The first experiment was done by flashing the surface of completed prints and then using a portable microscope to measure the height of the surface layer and necking between deposited filaments. The data were analyzed using a two-way ANOVA and the results did not conclude that the Sinteron was successful in reducing the gap. The second experiment was analyzed visually using an optical microscope and revealed that Sinteron might be able to reduce the gap on prints that are solid. The third experiment was analyzed using an optical microscope and the area of the gaps were measured using ImageJ software. The results concluded that the Sinteron was not successful in reducing the gap. The quantitative data from these experiments suggest that the proposed processing method would not be successful in reducing the anisotropy of 3D printed parts created by the FFF process. The recommendation is to investigate post processing methods such as a heat gun that would apply heat evenly across a layer

Embedding ultra-high-molecular-weight polyethylene fibers in 3D-printed Polylactic Acid (PLA) parts

This study aims to assess whether ultra-high-molecular-weight polyethylene (UHMWPE) fibers can be successfully embedded in a polylactic acid (PLA) matrix in a material extrusion 3D printing (ME3DP) process, despite the apparent thermal incompatibility between the two materials. The work started with assessing the maximum PLA extrusion temperatures at which UHMWPE fibers withstand the 3D printing process without melting or severe degradation. After testing various fiber orientations and extrusion temperatures, it has been found that the maximum extrusion temperature depends on fiber orientation relative to extrusion pathing and varies between 175 C and 185 C at an ambient temperature of 25 C. Multiple specimens with embedded strands of UHMWPE fibers have been 3D printed and following tensile strength tests on the fabricated specimens, it has been found that adding even a small number of fiber strands laid in the same direction as the load increased tensile strength by 12% to 23% depending on the raster angle, even when taking into account the decrease in tensile strength due to reduced performance of the PLA substrate caused by lower extrusion temperatures.EEA Grants/Norway GrantsPeer reviewe

Additive manufactured sandwich composite/ABS parts for unmanned aerial vehicle applications

Fused deposition modelling (FDM) is one of most popular 3D printing techniques of thermoplastic polymers. Nonetheless, the poor mechanical strength of FDM parts restricts the use of this technology in functional parts of many applications such as unmanned aerial vehicles (UAVs) where lightweight, high strength, and stiffness are required. In the present paper, the fabrication process of low-density acrylonitrile butadiene styrenecarbon (ABS) with carbon fibre reinforced polymer (CFRP) sandwich layers for UAV structure is proposed to improve the poor mechanical strength and elastic modulus of printed ABS. The composite sandwich structures retains FDM advantages for rapid making of complex geometries, while only requires simple post-processing steps to improve the mechanical properties. Artificial neural network (ANN) was used to investigate the influence of the core density and number of CFRP layers on the mechanical properties. The results showed an improvement of specific strength and elastic modulus with increasing the number of CFRP. The specific strength of the samples improved from 20 to 145 KN·m/kg while the Young’s modulus increased from 0.63 to 10.1 GPa when laminating the samples with CFRP layers. On the other hand, the core density had no significant effect on both specific strength and elastic modulus. A case study was undertaken by applying the CFRP/ABS/CFRP sandwich structure using the proposed method to manufacture improved dual-tilting clamps of a quadcopter UAV

Characterization of Mechanical Properties of Gamma Irradiated Additively Manufactured Articles for In-Space Manufacturing

Recently, additive manufacturing (AM) has opened many doors to engineers across various industries, such as medical, bio-engineering, automotive and recently, aerospace. In an effort to contribute to the development of AM in aerospace industry, a series of experiments were designed to help understand the behavior of 3D printed parts and extend its capabilities and possible uses. The first chapter of this project will focus on understanding the mechanical behavior of additively manufactured articles. In this chapter, a comprehensive effort was undertaken to represent the strength of a 3D printed object as a function of layer thickness by investigating the correlation between the mechanical properties of 3D printed parts and layer thickness. Results showed that samples printed with 0.2 mm layer thickness exhibit higher elastic modulus, ultimate strength and force compared with 0.4 mm. This result has a direct effect on decision making and future use of 3D printing; particularly functional load bearing parts. The second chapter is focused on the effects of gamma irradiation on mechanical properties of hybrid materials as an in-space 3D printing feedstock to investigate the forthcoming possibilities of this technology for future space exploration missions. 3D printed testing samples were irradiated at different dosages from 1 to 1400 kGy using a Cobalt-60 gamma irradiator to simulate space radiation environment. The correlation between the mechanical properties of irradiated samples and accumulated radiation dosage were evaluated by a series of tensile and flexural tests. Findings showed a significant decrease in mechanical performance and noticeable changes in appearance of the parts with accumulated dosage of 1000 kGy and higher. However, for dosages below 10 kGy, samples showed no significant decrease in mechanical performance or change in appearance. These results were used to predict the life of a 3D printed part and demonstrate their potential for use on board the international space station, on low earth orbit satellites, in deep space and long duration missions

Advancing the Underactuated Grasping Capabilities of Single Actuator Prosthetic Hands

The last decade has seen significant advancements in upper limb prosthetics, specifically in the myoelectric control and powered prosthetic hand fields, leading to more active and social lifestyles for the upper limb amputee community. Notwithstanding the improvements in complexity and control of myoelectric prosthetic hands, grasping still remains one of the greatest challenges in robotics. Upper-limb amputees continue to prefer more antiquated body-powered or powered hook terminal devices that are favored for their control simplicity, lightweight and low cost; however, these devices are nominally unsightly and lack in grasp variety. The varying drawbacks of both complex myoelectric and simple body-powered devices have led to low adoption rates for all upper limb prostheses by amputees, which includes 35% pediatric and 23% adult rejection for complex devices and 45% pediatric and 26% adult rejection for body-powered devices [1]. My research focuses on progressing the grasping capabilities of prosthetic hands driven by simple control and a single motor, to combine the dexterous functionality of the more complex hands with the intuitive control of the more simplistic body-powered devices with the goal of helping upper limb amputees return to more active and social lifestyles. Optimization of a prosthetic hand driven by a single actuator requires the optimization of many facets of the hand. This includes optimization of the finger kinematics, underactuated mechanisms, geometry, materials and performance when completing activities of daily living. In my dissertation, I will present chapters dedicated to improving these subsystems of single actuator prosthetic hands to better replicate human hand function from simple control. First, I will present a framework created to optimize precision grasping – which is nominally unstable in underactuated configurations – from a single actuator. I will then present several novel mechanisms that allow a single actuator to map to higher degree of freedom motion and multiple commonly used grasp types. I will then discuss how fingerpad geometry and materials can better grasp acquisition and frictional properties within the hand while also providing a method of fabricating lightweight custom prostheses. Last, I will analyze the results of several human subject testing studies to evaluate the optimized hands performance on activities of daily living and compared to other commercially available prosthesis

Electromagnetic Energy Coupled to Nanomaterial Composites for Polymer Manufacturing

Polymer nano-composites may be engineered with specific electrical properties to achieve good coupling with electromagnetic energy sources. This enables a wide range of novel processing techniques where controlling the precise thermal profile is critical. Composite materials were characterized with a variety of electrical and thermographic analysis methods to capture their response to electromagnetic energy. COMSOL finite element analysis software was used to model the electric fields and resultant thermal profiles in selected samples. Applications of this technology are demonstrated, including the use of microwave and radio frequency energy to thermally weld the interfaces of 3D printed parts together for increased interlayer (Z) strength. We also demonstrate the ability to bond various substrates with carbon nanotube/epoxy composite adhesives using radio frequency electromagnetic heating to rapidly cure the adhesive interface. The results of this work include 3D printed parts with mechanical properties equal to injection molded samples, and RF bonded joints cured 40% faster than traditional oven curing

Augmented Reality

Augmented Reality (AR) is a natural development from virtual reality (VR), which was developed several decades earlier. AR complements VR in many ways. Due to the advantages of the user being able to see both the real and virtual objects simultaneously, AR is far more intuitive, but it's not completely detached from human factors and other restrictions. AR doesn't consume as much time and effort in the applications because it's not required to construct the entire virtual scene and the environment. In this book, several new and emerging application areas of AR are presented and divided into three sections. The first section contains applications in outdoor and mobile AR, such as construction, restoration, security and surveillance. The second section deals with AR in medical, biological, and human bodies. The third and final section contains a number of new and useful applications in daily living and learning

2D to 3D non photo realistic character transformation and morphing (computer animation)

This research concerns the transformation and morphing between a full body 2D and 3D animated character. This practice based research will examine both technical and aesthetic techniques for enhancing morphing of animated characters. Stylized character transformations from A to B and from B to A, where details like facial expression, body motion, texture are to be expressively transformed aesthetically in a narrated story. Currently it is hard to separate 2D and 3D animation in a mix media usage. If we analyse and breakdown these graphical components, we could actually find a distinction as to how these 2D and 3D element increase the information level and complexity of storytelling. However, if we analyse it from character animation perspective, instance transformation of a digital character from 2D to 3D is not possible without post production techniques, pre-define 3D information such as blend shape or complex geometry data and mathematic calculation. There are mainly two elements to this investigation. The primary element is the design system of such stylizes character in 2D and 3D. Currently many design systems (morphing software) are based on photo realistic artifacts such as Fanta Morph, Morph Buster, Morpheus, Fun Morph and etc. This investigation will focus on non photo realistic character morphing. In seeking to define the targeted non photo realistic, illustrated stylize 2D and 3D character, I am examining the advantages and disadvantages of a number of 2D illustrated characters in respect to 3D morphing. This investigation could also help to analyse the efficiency and limitation of such 2D and 3D non photo realistic character design and transformation where broader techniques will be explored. The secondary element is the theoretical investigation by relating how such artistic and technical morphing idea is being used in past and today films/games. In a narrated story contain character that acts upon a starting question or situation and reacts on the event. The gap between his aim and the result of his acting, the gap between his vision and his personality creates the dramatic tension. I intend to distinguish the possibility of identifying a transitional process of voice between narrator and morphing character, while also illustrating, through visual terminology, the varying fluctuations between two speaking agents. I intend to prove and insert sample demonstrating “morphing” is not just visually important but have direct impact on storytelling