China
Africa
Explore chapters and articles related to this topic
Characteristics, Fabrication, and Design of Composites
Published in Sherif D. El Wakil, Processes and Design for Manufacturing, 2019
Embedding plies of glass, carbon, or polyaramid plain-weave fabric or fibrous mat into an uncured resin and allowing the liquid resin to solidify (cure) while being constrained by a mold or form is a common processing technique used in the pleasure boat building industry. A typical arrangement of the plies used in this technique, called the wet lay-up process, is shown in Figure 9.6. A recent automated version of this process is automated fiber placement, which involves placing the resin-impregnated fiber tows onto a mandrel using a numerically controlled head.
Strength evaluation of continuous curvilinear variable stiffness panels with circular cutouts under biaxial normal loading and off-design conditions
Published in Mechanics of Advanced Materials and Structures, 2022
Mahdi Arian Nik, Kazem Fayazbakhsh, Sadben Khan, Zouheir Fawaz
Efficiency and weight reduction have been major design goals for modern aerospace structures to alleviate carbon emissions and reduce operation cost. As a result, many designs have utilized optimization techniques to tailor structures to their peak efficiency. Composite laminates benefit greatly from optimization as innovations in advanced manufacturing techniques, e.g., automated fiber placement (AFP), have allowed for precise placement of fibers along prescribed paths using robotic or gantry-based systems. Using AFP technology, fibers can follow curvilinear paths and composite laminates are no longer limited to straight-fiber paths used in traditional designs. Curvilinear fiber paths allow for the stiffness of a structure to vary spatially resulting in a variable stiffness (VS) design. The introduction of the VS design results in structures with unique characteristics, like decoupling of stiffness and buckling load as well as significantly improving their load carrying capacity [1]. An interesting property of laminates utilizing a VS design, is the capability of the loads to be distributed across the panel. This concept can be used to improve the performance of structures featuring large cutouts, as these discontinuities are significant stress concentration regions. Typically, these areas are reinforced with doublers or thickness built-up that resist the higher stresses [2].
Micro-CT analysis of process-induced defects in composite laminates using AFP
Published in Materials and Manufacturing Processes, 2021
Ji-Youn Arns, Ebrahim Oromiehie, Christoph Arns, B. Gangadhara Prusty
Automated fiber placement (AFP) is one of the advanced techniques for making large composite structures. In this method, cutting, curing, and consolidation stages are combined in the placement head (Fig. 1). The AFP robot contains a 6-axis Kawasaki articulated robot arm, a placement head, and a coordinated spindle assembly.[2,22] With the start of the lay-up process, an incoming thermoplastic prepreg tape is compressed and consolidated to the substrate, using a consolidation roller, while it is being heated with a heating system (Hot gas torch). In the AFP process, the quality of manufactured laminate can be adversely affected through an improper selection of processing parameters. Some of these parameters are feed rate, curing temperature, heat flow rate, and consolidation force.
Continuous curvilinear variable stiffness design for improved strength of a panel with a cutout
Published in Mechanics of Advanced Materials and Structures, 2022
Sadben Khan, Mahdi Arian Nik, Kazem Fayazbakhsh, Zouheir Fawaz
Automated fiber placement (AFP) allows for precise placement of fibers using robotic or gantry-based systems that help develop low-cost and lightweight optimized structures. The automated technology allows for accurate plies placement according to CAD data, which helps fully utilize the directional properties of composite materials. Tailoring fibers along a non-straight path cause the fiber orientation, and thus, properties such as stiffness vary spatially, resulting in a variable stiffness (VS) design [1]. The introduction of VS in a laminate design creates novel characteristics and the potential for significantly improving its load carrying capacity in different applications.