Composites Part Production with Additive Manufacturing Technologies

Additive Manufacturing (AM) is of particular interest in the context of composite part production as AM promises the production of integrated, complex structures with low lead times. Currently, AM is used for tooling and sandwich cores with added functionalities. This paper presents four design principles that improve the production of composites parts during layup, handling, curing and post processing in the layup process. Design principles are applied to a hat-stiffener, a highly integrated aircraft instrument panel and a novel insert eliminating drilling operations. Results show that AM can reduce the part count, assembly steps and deformations during curing

An optimality criteria-based algorithm for efficient design optimization of laminated composites using concurrent resizing and scaling

Numerical optimization is an indispensable part of the design process of laminated composite structures. Several optimality criteria-based algorithms exist which rely on a sequential resizing and scaling approach. This paper presents a novel design algorithm applicable for stiffness and eigenfrequency optimization of composite structures with concurrent consideration of resizing and scaling operations. A method is introduced that allows for an efficient consideration of nonlinear constraints. This is done by determining stable concurrent scaling parameters from first-order constraint change ratio estimations. Optimization is carried out using optimality criteria in three independent steps, namely with respect to fiber angles, ply thickness ratios, and total laminate thickness. Sensitivity analyses are performed analytically at low computational costs. Numerical examples demonstrate the efficiency and fast convergence of the method. Compared to established algorithms, the number of required function evaluations is reduced significantly.ISSN:1615-147XISSN:1615-148

Precisely Adjustable Inserts for Stiffness-Driven CFRP Sandwich Structures

Carbon fiber reinforced plastic application, as a substitute for more traditionally applied materials like steel and aluminum, allows for combining lower mass with higher stiffness, and thus an increase in performance of highly-dynamic multiaxial testing machines. A novel through-the-thickness insert was developed to allow load transfer in stiffness-driven CFRP sandwich structures. The insert consists of two parts, is machined with an economical turning process, and features a fine thread which allows it to be accurately tuned, compensating for any potential CFRP sandwich thickness variations. The insert's external surfaces can be milled, meeting the tolerances needed for mating with other components.ISSN:2212-827

Carbon Fiber Reinforced Polymers for High-Dynamic Testing Machines

Main design objective of high-dynamic multiaxial testing machines is a high fundamental frequency. Carbon fiber reinforced polymers (CFRP) offer outstanding weight-specific properties and high design freedom. They are thus a promising choice for the development of novel testing machines. This paper investigates the challenges which are decisive for a successful implementation of the FRP technology. In order to assess the potential of the approach, an optimized CFRP testing machine is compared to a state-of-the-art metal design. Significantly improved performance at comparable costs indicates that the CFRP technology is a valuable asset to the design of complex low volume special-purpose machines.ISSN:2212-827

Composites Part Production with Additive Manufacturing Technologies

Additive Manufacturing (AM) is of particular interest in the context of composite part production as AM promises the production of integrated, complex structures with low lead times. Currently, AM is used for tooling and sandwich cores with added functionalities. This paper presents four design principles that improve the production of composites parts during layup, handling, curing and post processing in the layup process. Design principles are applied to a hat-stiffener, a highly integrated aircraft instrument panel and a novel insert eliminating drilling operations. Results show that AM can reduce the part count, assembly steps and deformations during curing.ISSN:2212-827

Individualized lightweight structures for biomedical applications using additive manufacturing and carbon fiber patched composites

Combining additive manufacturing (AM) with carbon fiber reinforced polymer patched composites unlocks potentials in the design of individualized, lightweight biomedical structures. Arising design opportunities are geometrical individualization of structures using the design freedom of AM and the patient-individual design of the load-bearing components employing carbon fiber patch placement. To date, however, full exploitation of these opportunities is a complex recurring task, which requires a high amount of knowledge and engineering effort for design, optimization, and manufacturing. The goal of this study is to make this complexity manageable by introducing a suitable manufacturing strategy for individualized lightweight structures and by developing a digitized end-to-end design process chain, which provides a high degree of task automation. The approach to achieve full individualization uses a parametric model of the structure which is adapted to patients’ 3D scans. Moreover, patient data is used to define individual load cases and perform structural optimization. The potentials of the approach are demonstrated on an exoskeleton hip structure. A significant reduction of weight compared to a standard design suggests that the design and manufacturing chain is promising for the realization of individualized high-performance structure