PACS—Realization of an adaptive concept using pressure actuated cellular structures

Abstract

A biologically inspired concept is investigated which can be utilized to develop energy efficient, lightweight and applicational flexible adaptive structures. Building a real life morphing unit is an ambitious task as the numerous works in the particular field show. Summarizing fundamental demands and barriers regarding shape changing structures, the basic challenges of designing morphing structures are listed. The concept of Pressure Actuated Cellular Structures (PACS) is arranged within the recent morphing activities and it is shown that it complies with the underlying demands. Systematically divided into energy-related and structural subcomponents the working principle is illuminated and relationships between basic design parameters are expressed. The analytical background describing the physical mechanisms of PACS is presented in concentrated manner. This work focuses on the procedure of dimensioning, realizing and experimental testing of a single cell and a single row cantilever made of PACS. The experimental outcomes as well as the results from the FEM computations are used for evaluating the analytical methods. The functionality of the basic principle is thus validated and open issues are determined pointing the way ahead.

Development and Testing of Woven FRP Flexure Hinges for Pressure-Actuated Cellular Structures with Regard to Morphing Wing Applications

“…For all of these subsystems, conceptual solutions are developed and presented in detail in previous publications [21][22][23][24][25]. The holistic design approach is illustrated in Figure 7.…”

“…Accordingly, FRP prove to be particularly suitable for PACS. In initial trials, the functionality of PACS was demonstrated on a single-row cantilever made of pre-impregnated glass-fiber reinforced plastics (GFRP) [21]. However, the manufacturing process turns out to be complex, time-consuming, and difficult to reproduce.…”

“…The biomimetic approach of PACS was first investigated by Pagitz et al with regard to technical applications and translated into a two-dimensional concept [20]. Gramüller et al further developed the theoretical concept to technical maturity and were able to demonstrate the outstanding flexibility of such structures to achieve arbitrary form functions [21,22]. The design methodology is based on an optimization algorithm developing a two-dimensional truss structure.…”

Evaluation of a Compliant Droop-Nose Morphing Wing Tip via Experimental Tests

“…A strain energy-based objective function may lead to a better balance of stiffness and flexibility and may also implicitly consider actuator size and system weight in the design. As evident, further development of the continuum gradient-based topology optimization method is required and given the ability of this method to generate optimum designs from an essentially 'blank canvas' warrants this development, especially for the design of special compliant mechanisms such as pressurized compliant structures [48][49][50].…”

Development of 3D woven cellular structures for adaptive composites based on thermoplastic hybrid yarns

“…This also includes pressure-actuated cellular structures (PACS, cf. Figure 1), which have so far only been investigated theoretically [1], [2]. The aim of this project is to develop theoretical and experimental basics for the development, production and testing of woven PACS.…”