Morphing aircraft wings offer great potential benefits of achieving multi mission capability as well as high
maneuverability under different flight conditions. However, they present many design challenges in the form of
conflicting design requirements. The current research aims to develop design methodologies for the design of a
morphing aircraft wing. Focus of this work is on developing an internal mechanism of the wing that can produce the
desired wing shape change.
This paper presents a design methodology that employs planar unit cells of pre-determined shape and layout as the
internal wing structure for achieving the desired wing shape change. This method is particularly useful in cases where
the desired morphing is two-dimensional in nature. In such cases, intuitive cell designs such as diamond or hexagonal
shaped cells may be used in layouts that achieve desired wing morphing. The shape change depends on the cell shape as
well as cell arrangement in the design domain.
In this paper, a design based on the TSCh wing (NextGen Aeronautics Inc.) using cellular mechanisms to achieve a two-dimensional
wing shape change is discussed. Additionally, a reeling mechanism for achieving cable actuation is presented
Achieving multi-mission capability with a single aircraft through in-flight morphing of the wing is highly beneficial due
to its efficiency under different flight conditions such as cruise and dash. In addition higher maneuverability is possible
from using such a vehicle. As opposed to traditional wing morphing where discrete surfaces such as hinged flaps and
ailerons are used, the current research focus is directed towards achieving continuous morphing in order to reduce drag
from geometric discontinuities.
The present research aims to achieve continuous wing morphing by employing a wing structure comprised of an
optimized internal layout of cables and struts. Cables are used as actuators while struts provide rigidity to the wing. In
addition to achieving continuous morphing by changing cable length, this structure has the advantage of being light in
weight. Also, distributed actuation may be achieved from this scheme.
Topology optimization is utilized to optimally place cables and struts in a "bay" or a section of the wing. The
optimization is achieved by using Genetic Algorithm. A Generic Algorithm, the Non-dominated Sorting Genetic
Algorithm II (NSGA II) has been used in this work. The current paper gives an overview of the algorithm and discusses
obtained results.
The idea of a morphing aircraft wing has generated considerable interest in recent years. Such a structure has inherent advantages of possessing high maneuverability and efficiency under different flight conditions such as take off, cruise and loiter. The current focus is on achieving continuous wing shape change, as opposed to discrete, in order to help reduce drag. This research aims to achieve continuous wing morphing by employing a wing structure comprising of an optimized internal layout of cables and struts. Cables are employed as actuators while struts provide rigidity to the wing. In addition to achieving continuous morphing by changing cable length, this structure has the advantage of being light in weight.
The focus of this paper is on obtaining an optimized cable and strut layout in the body of the wing. Non-linear Finite Element Analysis (FEA) has been performed to account for the large deflection requirements. An objective function that considers deflection under actuation and air loads has been incorporated. Results comparing linear and non-linear FEA are presented for a particular wing design. The nonlinear finite element is found to be effective when using large actuation forces.
Continuously morphing aircraft wings are currently a focus of considerable research. Efforts are being made to achieve effective and optimal wing shape change under different flight conditions such as take off, cruise, dash, and loiter. The present research aims to achieve wing morphing by using an internal structure consisting of actuated tendons and passive struts. An important aspect of this approach is determining the optimal layout of tendons and struts. In this paper a genetic algorithm is developed to optimize the three-dimensional tendon-strut layout for a prescribed wing geometry and shape change. The method is applied to two morphing wing applications, the NASA HECS wing and NextGen TSCh wing.
In the use of piezoelectric actuators, it is a clear choice to use stack (or d33 mode) architectures when very high force is required or benders (or d31 mode) architectures when very high displacements are needed. However, the choice isn't as clear for applications that need simultaneously a moderate force and displacement. This paper presents one such application, INSTAR that is posed with this dilemma. INSTAR is a novel rifle system that has an inertially stabilized barrel via an active suspension based on piezoelectric actuation. While the frequency required for this application was low (~10Hz), the displacement (± 200 to 400 microns) and the force (22-45 N) are moderate. Two very different actuation approaches were developed, modeled, fabricated and experimentally validated within the INSTAR demonstration platform: 1) a d31 approach based on the Recurve architecture with focus on generating higher forces than is common for d31 actuators and 2) a d33 approach based upon a compliant mechanism designed using topology optimization with focus on providing more amplified strain than is common for d33 actuators. Both approaches were successful in meeting the INSTAR requirements, but each had its on advantages and disadvantages.
Compliant mechanical amplifiers are often used to amplify small motions such as those of PZT actuators, since they do not incur displacement losses that frequently occur in pin-jointed mechanisms. Their optimal design is key to maximizing actuator performance. Our previous work was focused on developing a topology optimization methodology wherein the size of the design domain and the location of the PZT actuator were pre-defined. The resultant solution was one that maximized stroke amplification. In this paper we study the effects of stack and structural properties on resultant topology and output stroke with focus on quantitative performance for practical application. The motivating example is an actuator-design problem where +/- 400micrometers stroke and 45 N force is required. The problem is solved using topology design methodology and the results obtained are verified using finite element analysis. We demonstrate that magnitude of output displacement is extremely sensitive to preload on the compliant mechanical amplifier, amplifier and actuator material, topology interpretation while converting it into a solid model, and magnitude of applied voltage. We discuss effects of asymmetric placement of the PZT stack, multiple stacks, and increased stack length on resultant displacement.
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