Design Automation and Additive Manufacturing for Anatomically Diversified Medical Simulators

The education and continuous exercise of manual skills in invasive medical procedures requires training environments that are safe, cost efficient and realistic. While body parts of humans and animals offer the most realism they are expensive and challenging in storage, handling and disposal. Therefore, training scenarios for medical staff commonly use artificial simulators to practice individual skills and team performance. These simulators usually do not reflect the diversity in human anatomy. Simulators for a certain task are commonly offered only in one shape and size to reduce cost in design and manufacturing. A more diverse anatomy could improve the training of medical staff. This work uses additive manufacturing for the cost efficient production of molds and components for silicone casted customized simulators. Furthermore a design automated approach is presented that allows non-engineers to specify the desired anatomy. The process chain is validated on a simulator for pneumothorax decompression. The main element of the simulator is an insert, which is cut and stitched during the procedure. The insert is a single-use disposable representing ribs, muscles, fat and skin. The new simulator insert offers improved aesthetic and tactile properties. The automated design and additive manufacturing allow non-engineers to adapt the insert to body mass index, age, gender and ethnicity

Design Guidelines for Additive Manufactured Snap-Fit Joints

Snap-fit joints are one of the cheapest and fastest connectors available. However, due to geometrical complexity of the joints and the limitations of injection molding, they are used almost exclusively in large-scale manufactured products. Additive manufacturing offers the possibility to create end-user products in small and medium numbers with almost unlimited design complexity. This clears the way for new solutions using snap-fit joints to be explored. In this contribution, the existing design guidelines for snap-fit joints are challenged with the design potentials of additive manufacturing. The general working principles of snap-fit joints prove to be simple, clear, and safe independent of the manufacturing process. While the principles remain unchanged, the advantages of additive manufacturing are utilized to improve the integration in the product and the user handling. By applying the design restrictions of the additive manufacturing processes Fused Deposition Modeling (FDM) and Selective Laser Sintering (SLS) the existing guidelines are extended for new manufacturing processes. To demonstrate the new concepts and the capabilities of additive manufactured snap-fit joints a showcase is conceptualized, designed in detail and produced using Fused Deposition Modeling and Selective Laser Sintering. A lid of a container, similar to a jar, is designed as an integrated single component. Aspects of haptics and usability are integrated, resulting in a lid that can easily be assembled and disassembled using one hand only. The design features springs and snap-fit joints adapted to the advantages and limitations of additive manufacturing

Considering Part Orientation in Design for Additive Manufacturing

Additive Manufacturing (AM) is established not only in prototyping, but also in serial production of end-use products. To use the full potential of the production technology the restrictions of current additive manufacturing processes (like support structures in Selective Laser Melting) must be considered in the design process. Especially the compliance with design rules from early design stages on is important in AM serial production, due to production quantities and the resulting scale effect. The part orientation in the build space has a strong influence on many quality characteristics. In order to use the full potential and to consider the restrictions from the start, a design guideline is necessary to support the whole design process. For this purpose, this paper presents a framework for design guidelines. The framework distinguishes between process characteristics, design principles and design rules; each supporting the designer during different stages of the design process. Furthermore, the paper examines the influence of part orientation in existing design rules and elaborates its importance. Based on this result, the design principle “early determination of part orientation” is presented, which includes a process for determining the part orientation in early stage of the design process. In addition, a design process for additive manufactured parts is demonstrated on an extensive showcase, following the guideline framework and including the principle for early determination of part orientation. The presented framework proved to be helpful in the design process and will be used in the future to collect more process characteristics, design principles and rules

Additive Manufacturing of Structural Cores and Washout Tooling for Autoclave Curing of Hybrid Composite Structures

This paper presents a study combining additive manufactured (AM) elements with carbon fiber-reinforced polymers (CFRP) for the autoclave curing of complex-shaped, lightweight structures. Two approaches were developed: First, structural cores were produced with AM, over-laminated with CFRP, and co-cured in the autoclave. Second, a functional hull is produced with AM, filled with a temperature- and pressure-resistant material, and over-laminated with CFRP. After curing, the filler-material is removed to obtain a hollow lightweight structure. The approaches were applied to hat stiffeners, which were modeled, fabricated, and tested in three-point bending. Results show weight savings by up to 5% compared to a foam core reference. Moreover, the AM element contributes to the mechanical performance of the hat stiffener, which is highlighted by an increase in the specific bending stiffness and the first failure load by up to 18% and 310%. Results indicate that the approaches are appropriate for composite structures with complex geometries

Enabling non-engineers to use engineering tools: introducing product development to pupils using knowledge-integrating systems

Many engineering tasks are supported by tools based on innovative technologies. Powerful tools for computer aided design, simulations or programming permit a wide range of possibilities for engineers in solving complex problems. However, using these tools commonly requires extensive training or specific skills. Specialized systems that enable tool and technology usage could support novices in solving engineering tasks using embedded knowledge, lowering the hurdle of expertise required for operation. In the presented case study, knowledge-integrating systems inspired by knowledge-based engineering were developed to allow pupils to solve an engineering challenge without existing skills or prior training. To provide a realistic application context, a teaching module was developed, introducing high school students to product engineering in the form of a conceive-design-implement-operate experience with the learning goal to engage them in the STEM field. Solving the included engineering challenge required the creation, test and iteration of designs for laser cut and additive manufacturing, and code processing sensor signals for motor actuation. To evaluate the knowledge-integrating systems in their use qualitatively, a trial run was conducted. Participants were enabled to fulfil basic product engineering tasks and expressed engagement in product development and overall satisfaction. The module’s key element is an educational exoskeleton that can be controlled by electromyography signals. It is modified to eventually support a fictional character suffering from monoplegia. The module was realized accompanying the CYBATHLON, a championship for people with physical disabilities in solving everyday tasks assisted by state-of-the-art technical systems

Bender – An Educational Game for Teaching Agile Hardware Development

Within this paper, an educational game is presented that transfers Agile principles for the development of physical systems. The training leverages elements of Learning Factories (LF) to simulate an Agile hardware development project within two days. By doing so, the challenges of applying Agile within the hardware domain are realistically reflected. The training revolves around a physical wire bending machine, which a development team of four participants needs to modify within a realistic engineering and production setting. A trial with mechanical engineering students was conducted to validate the training design. The participants showed a positive attitude towards the active learning approach. Furthermore, the students expressed that they perceived the game to improve their learning regarding Agile hardware development