scispace - formally typeset
Search or ask a question
Author

Andrea Ehrmann

Bio: Andrea Ehrmann is an academic researcher from Bielefeld University of Applied Sciences. The author has contributed to research in topics: Nanofiber & Electrospinning. The author has an hindex of 22, co-authored 249 publications receiving 2136 citations. Previous affiliations of Andrea Ehrmann include University of Hohenheim & Silesian University of Technology.


Papers
More filters
Journal ArticleDOI
08 Aug 2014
TL;DR: The Fused Deposition Modelling (FDM) technique as mentioned in this paper uses a plastic filament which is pushed through a heated extrusion nozzle melting the material, and different challenges occur in the production process, and the produced part shows different mechanical properties.
Abstract: 3D printing is a form of additive manufacturing, i.e. creating objects by sequential layering, for pre-production or production. After creating a 3D model with a CAD program, a printable file is used to create a layer design which is printed afterwards. While often more expensive than traditional techniques like injection moulding, 3D printing can significantly enhance production times of small parts produced in small numbers, additionally allowing for large flexibility and the possibility to create parts that would be impossible to produce with conventional techniques. The Fused Deposition Modelling technique uses a plastic filament which is pushed through a heated extrusion nozzle melting the material. Depending on the material, different challenges occur in the production process, and the produced part shows different mechanical properties. The article describes some standard and novel materials and their influence on the resulting parts.

242 citations

Journal ArticleDOI
TL;DR: Investigations show that while FDM printing allows for producing objects with mechanical properties similar to the original materials, metal-polymer blends cannot be used for the rapid manufacturing of objects necessitating mechanical strength.
Abstract: Fused deposition modeling (FDM) is a three-dimensional (3D) printing technology that is usually performed with polymers that are molten in a printer nozzle and placed line by line on the printing bed or the previous layer, respectively. Nowadays, hybrid materials combining polymers with functional materials are also commercially available. Especially combinations of polymers with metal particles result in printed objects with interesting optical and mechanical properties. The mechanical properties of objects printed with two of these metal-polymer blends were compared to common poly (lactide acid) (PLA) printed objects. Tensile tests and bending tests show that hybrid materials mostly containing bronze have significantly reduced mechanical properties. Tensile strengths of the 3D-printed objects were unexpectedly nearly identical with those of the original filaments, indicating sufficient quality of the printing process. Our investigations show that while FDM printing allows for producing objects with mechanical properties similar to the original materials, metal-polymer blends cannot be used for the rapid manufacturing of objects necessitating mechanical strength.

106 citations

Journal ArticleDOI
16 Jul 2015
TL;DR: In this paper, different approaches to combine 3D printed polymers with different textile materials and fabrics, showing chances and limits of this technique, are discussed, and the main challenge of 3D printing is the insufficient mechanical properties, especially the low tensile strength.
Abstract: The 3D printing belongs to the rapidly emerging technologies which have the chance to revolutionize the way products are created. In the textile industry, several designers have already presented creations of shoes, dresses or other garments which could not be produced with common techniques. 3D printing, however, is still far away from being a usual process in textile and clothing production. The main challenge results from the insufficient mechanical properties, especially the low tensile strength, of pure 3D printed products, prohibiting them from replacing common technologies such as weaving or knitting. Thus, one way to the application of 3D printed forms in garments is combining them with textile fabrics, the latter ensuring the necessary tensile strength. This article reports about different approaches to combine 3D printed polymers with different textile materials and fabrics, showing chances and limits of this technique.

98 citations

Journal ArticleDOI
TL;DR: In this article, the recent advancements in the fabrication of carbon nanofibers and additionally pointing out their significance for applications in the industrial and biomedical sector for their potential role in the future.

93 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the adhesion between polymer-textile composites and showed that the dependence of the polymertextile adhesion force was evaluated according to the distance between both compound partners, and that significantly different adhesion values can be found in such 3D printed composites.
Abstract: Composites combining two or more different materials with different physical and chemical properties allow for tailoring mechanical and other characteristics of the resulting multi-material system. In relation to fiber-reinforced plastic composites, combinations of textile materials with 3D printed polymers result in different mechanical properties. While the tensile strength of the multi-material system is increased compared to the pure 3D printed material, the elasticity of the polymer layer can be retained to a certain degree, as the textile material is not completely immersed in the polymer. Instead, an interface layer is built in which both materials interpenetrate to a certain degree. The purpose of this study is to investigate the adhesion between both materials at this interface.,This paper gives an overview of the parameters affecting the interface layer. It shows that both the printing material and the textile substrate influence the adhesion between both materials due to viscosity during printing, thickness and pore sizes, respectively. While some material combinations build strong form-locking connections, others can easily be delaminated.,Depending on both materials, significantly different adhesion values can be found in such 3D printed composites.,This makes some combinations very well suitable for building composites with novel mechanical properties, while other suffer of insufficient connections.,For the first time, the dependence of the polymer-textile adhesion force was evaluated according to the distance between both compound partners. It was shown that this value is of crucial interest and must thus be taken into account when producing printed polymer-textile composites.

73 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: Polymers are by far the most utilized class of materials for AM and their design, additives, and processing parameters as they relate to enhancing build speed and improving accuracy, functionality, surface finish, stability, mechanical properties, and porosity are addressed.
Abstract: Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

2,136 citations

Journal ArticleDOI
TL;DR: In this paper, the authors give an overview on 3D printing techniques of polymer composite materials and the properties and performance of 3D printed composite parts as well as their potential applications in the fields of biomedical, electronics and aerospace engineering.
Abstract: The use of 3D printing for rapid tooling and manufacturing has promised to produce components with complex geometries according to computer designs. Due to the intrinsically limited mechanical properties and functionalities of printed pure polymer parts, there is a critical need to develop printable polymer composites with high performance. 3D printing offers many advantages in the fabrication of composites, including high precision, cost effective and customized geometry. This article gives an overview on 3D printing techniques of polymer composite materials and the properties and performance of 3D printed composite parts as well as their potential applications in the fields of biomedical, electronics and aerospace engineering. Common 3D printing techniques such as fused deposition modeling, selective laser sintering, inkjet 3D printing, stereolithography, and 3D plotting are introduced. The formation methodology and the performance of particle-, fiber- and nanomaterial-reinforced polymer composites are emphasized. Finally, important limitations are identified to motivate the future research of 3D printing.

2,132 citations

Journal ArticleDOI
TL;DR: In this article, the authors provide a brief discussion about additive manufacturing and also the most employed additive manufacturing technologies for polymers, specifically, properties under different loading types such as tensile, bending, compressive, fatigue, impact and others.
Abstract: 3D printing, more formally known as Additive Manufacturing (AM), is already being adopted for rapid prototyping and soon rapid manufacturing. This review provides a brief discussion about AM and also the most employed AM technologies for polymers. The commonly-used ASTM and ISO mechanical test standards which have been used by various research groups to test the strength of the 3D-printed parts have been reported. Also, a summary of an exhaustive amount of literature regarding the mechanical properties of 3D-printed parts is included, specifically, properties under different loading types such as tensile, bending, compressive, fatigue, impact and others. Properties at low temperatures have also been discussed. Further, the effects of fillers as well as post-processing on the mechanical properties have also been discussed. Lastly, several important questions to consider in the standardization of mechanical test methods have been raised.

822 citations

Journal ArticleDOI
TL;DR: With worldwide efforts, innovations in chemistry and materials elaborated in this review will push forward the frontiers of smart textiles, which will soon revolutionize the authors' lives in the era of Internet of Things.
Abstract: Textiles have been concomitant of human civilization for thousands of years. With the advances in chemistry and materials, integrating textiles with energy harvesters will provide a sustainable, environmentally friendly, pervasive, and wearable energy solution for distributed on-body electronics in the era of Internet of Things. This article comprehensively and thoughtfully reviews research activities regarding the utilization of smart textiles for harvesting energy from renewable energy sources on the human body and its surroundings. Specifically, we start with a brief introduction to contextualize the significance of smart textiles in light of the emerging energy crisis, environmental pollution, and public health. Next, we systematically review smart textiles according to their abilities to harvest biomechanical energy, body heat energy, biochemical energy, solar energy as well as hybrid forms of energy. Finally, we provide a critical analysis of smart textiles and insights into remaining challenges and future directions. With worldwide efforts, innovations in chemistry and materials elaborated in this review will push forward the frontiers of smart textiles, which will soon revolutionize our lives in the era of Internet of Things.

536 citations

01 Mar 2004
TL;DR: In this article, a theoretical model is presented for the behavior of rod-like particles representing CNTs in electrospinning, and the degrees of orientation of polymer, surfactant, and MWCNT are studied using X-ray dif...
Abstract: The electrospinning process was used successfully to fabricate nanofibers of poly(ethylene oxide) (PEO) in which multiwalled carbon nanotubes (MWCNT) are embedded. Initial dispersion of MWCNTs in water was achieved using amphiphiles, either as small molecules (sodium dodecyl sulfate, SDS) or as a high molecular weight, highly branched polymer (Gum Arabic). These dispersions provided separation of the MWCNTs and their individual incorporation into the PEO nanofibers by subsequent electrospinning. The focus of this work is on the development of axial orientations in these multicomponent nanofibers. A theoretical model is presented for the behavior of rodlike particles representing CNTs in electrospinning. Initially the rods are randomly oriented, but due to the sinklike flow in a wedge they are gradually oriented mainly along the stream lines, so that straight CNTs are almost oriented upon entering the electrospun jet. The degrees of orientation of polymer, surfactant, and MWCNT were studied using X-ray dif...

445 citations