No abstract

No abstract

Design and manufacturing of composite structures are driving the next generation innovation cycles for the aerospace, automotive and energy markets. Automated fiber placement (AFP) is quickly becoming the preferred manufacturing method of those structures as it offers manufacturing automation, reduces production cycle times, and decreases human induced errors. One of the major steps towards manufacturing structures with AFP technology is the selection of the optimal layup strategy. This is limited by, not only geometrical and process parameters, but certification allowable and guidelines. This paper outlines a systematic review of the multiple layup strategies practices currently used and/or investigated for the AFP manufacturing process. The optimal layup strategy needs to be selected and verified to obtain laminates with little to no manufacturing defects. Through a methodical description, the different layup strategies found in the literature are described as well as their mathematical implementation. Following, a geometrical benchmark is presented so that new layup strategies can be compared to others based on the same reference. The article can be the foundation for any new layup strategy investigation.

Parallel kinematic mechanism has shown its advantages as a high-precision motion stage in a machine tool. In this paper, a RPS-XY hybrid kinematic structure TRIPOD actuated by linear ultrasonic motors is proposed and designed for a five-axis ultra-precision micro machine tool. In the designing stage, both the titling capacity and the consistency of the deflecting abilities in all directions need to be carefully designed to overcome the platform's limitation in the freeform surface machining. This study proposes an optimizer that can automatically search for a set of design parameters of the 3-RPS parallel part to generate large titling and uniform deflecting capacities simultaneously. A specified orientation workspace is calculated to evaluate the ability of rotation. Additionally, a new index is introduced to justify the uniform deflecting capacity. By evaluating those factors as the objective functions, a modified NSGA-II algorithm is employed for the optimum design with the consideration of discretely selected linear guides and spherical joints from a predefined database, which contains the abstracted engineering models of commercial products. Optimal results verify the feasibility and effectiveness of the proposed optimizer in designing a physical platform. The technique is extensible to most of other parallel mechanisms as a standard procedure.

No abstract