Matthias Bock

Clarifying vibrational issues of an advanced automated fiber placement production plant

Advanced Fiber Placement is the technology being used to manufacture large-area, high quality parts of fiber composite materials. Due to the large-scale the production cycles are long and the parts become very expensive. One promising approach for improvement is to increase the desired laying accuracy to avoid degraded parts combined with higher laying speed. This paper deals with vibrations caused by operating plant components which reduce the production accuracy and speed for composites. Therefore, vibrational issues concerning single and linked elements of the production plant are in focus. Accordingly, the test setup consisting of autonomous data logger, and sensing elements is illustrated. Different scenarios to gain measurement data are studied. The recorded data is analyzed to explore the source of vibration. The vibrations origin is based on eigenfrequencies and the related eigenmodes are excited by operation. Based on the analyzed data an optimized plant layout is proposed. The use of additional sensors and smart structures technology is discussed.

Relation between repeatability and speed of robot-based systems for composite aircraft production through multilateration sensor system

Fiber composites are becoming increasingly important in different fields of lightweight application. To guarantee the estimated demand of components made of carbon fiber reinforced plastics the use of industrial robots is suggested in production. High velocity of the layup process is addressed to significantly increase the production rate. Today, the layup of the fiber material is performed by gantry systems. They are heavy weight, slow and the variety of possible part shapes is limited. Articulated robots offer a huge operational area in relation to their construction size. Moreover, they are flexible enough to layup fiber material into different shaped molds. Thus, standard articulated robots are less accurate and more susceptible to vibration than gantry systems. Therefore, this paper illustrates an approach to classify volumetric errors to obtain a relation between the achievable speed in production and precision. The prediction of a precision at a defined speed is the result. Based on the measurement results the repeatability of the robotic unit within the workspace is calculated and presented. At the minimum speed that is applicable in production the repeatability is less than 30 mm. Subsequently, an online strategy for path error compensation is presented. The approach uses a multilateration system that consists of four laser tracer units and measures the current absolute position of a reflector mounted at the end-effector of the robot. By calculating the deviation between the planned and the actual position a compensated motion is applied. The paper concludes with a discussion for further investigations.

Development and construction of an automated curing system for CFRP-Slittapes

The usage of pre-impregnated carbon fibers (prepregs) in the aviation is an essential part for manufacturing lightweight constructions. One specific kind of prepregs are slittapes. These are about ¼ broad unidirectional fiber-reinforced plastics, which are used in winding or fiber placement technology. At this time, components are produced by the mentioned practices and subsequently, they are cured in autoclaves. The main problem with the current state of technology is the rather expensive storage of the semi-finished composite-material. For this reason, the cure-process should be moved to the beginning of the production process which means to cure the slittapes before production. Afterwards, particular layers are bonded together under pressure. Basis of this innovative processing-method is a new generation of fiber placement heads which are able to process the pre-consolidated slittapes. In order to make further investigations to tape laying heads and the bonding method, it is necessary to be able to produce large quantities of pre-cured slittapes of a consistent quality. The objective of this paper is to develop a construction which is able to unwind the slittape material from the stock, cure it, and finally to wind it again up on a mandrel.