Kernel Principal Component Analysis for Structural Health Monitoring and Damage Detection of an Engineering Structure Under Operational Loading Variations

This paper highlights kernel principal component analysis (KPCA) in distinguishing damage-sensitive features from the effects of liquid loading on frequency response. A vibration test is performed on an aircraft wing box incorporated with a liquid tank that undergoes various tank loading. Such experiment is established as a preliminary study of an aircraft wing that undergoes operational load change in a fuel tank. The operational loading effects in a mechanical system can lead to a false alarm as loading and damage effects produce a similar reduction in the vibration response. This study proposes a non-nonlinear transformation to separate loading effects from damage-sensitive features. Based on a baseline data set built from a healthy structure that undergoes systematic tank loading, the Gaussian parameter is measured based on the distance of the baseline data set to various damage states. As a result, both loading and damage features expand and are distinguished better. For novelty damage detection, Mahalanobis square distance (MSD) and Monte Carlo-based threshold are applied. The main contribution of this project is the nonlinear PCA projection to understand the dynamic behavior of the wing box under damage and loading influences and to differentiate both effects that arise from the tank loading and damage severities.

Enhanced pose adjustment system for wing-box assembly in large aircraft manufacturing

Strict quality requirements in aircraft manufacturing demand high accuracy concerning pose alignments of aircraft structures. However, even though a pose adjustment system does pass the accuracy verification, the pose of the large complex structure has difficulty in smoothly and efficiently converging on the desired pose in large aircraft assembly. To solve this problem, we developed a pose adjustment system enhanced by integrating physical simulation for the wing-box assembly of a large aircraft. First, the development of the pose adjustment system, which is the base of the digital pose alignment of a large aircraft’s outer wing panel, is demonstrated. Then, the pose alignment principles of duplex and multiple assembly objects based on the best-fit strategy are successively explored. After that, the contributor analysis is conducted for nonideal pose alignment, in which the influences of thermal and gravity deformations on the pose alignment are discussed. Finally, a physical simulation-assisted pose alignment method considering multisource errors, which uses the Finite Element Analysis (FEA) to integrate temperature fluctuation and gravity field effects, is developed. Compared with a conventional digital pose adjustment system driven by the classical best-fit, the deviations of the Key Characteristic Points (KCPs) significantly decreased despite the impacts of thermal and gravity deformations. The developed pose alignment system has been applied to large aircraft wing-box assembly in Aviation Industry Corporation of China, Ltd. It provides an improved understanding of the pose alignment of large-scale complex structures.

МЕТОД ВИЗНАЧЕННЯ ХАРАКТЕРИСТИК ЗАГАЛЬНОГО НАПРУЖЕНО-ДЕФОРМОВАНОГО СТАНУ В СИЛОВИХ ЕЛЕМЕНТАХ КОНСОЛІ КРИЛА ВІД НАВАНТАЖЕННЯ ФУНКЦІОНУВАННЯ

When the high - lift system are released, the aerodynamic flow around the wing changes significantly, which in turn leads to a change in the stress-strain state of the wing. This is due not only to an increase in lift due to a change in the curvature of the wing and an increase in the wing area, but also a change in the position of the center of pressure relative to the wing chord. A significant increase in torque leads to a change in the stress-strain state of the wing mean joints. An aerodynamic calculation was performed using ANSYS CFX to obtain the position of the point of action of the lift force in each elements of the wing (slat, wing box and flap). Were obtained the relative positions of the points of action of the lift of individual parts of the wing: the slat, the wing box and the flap. These values were used to apply the forces acting from the high - lift system. The distributed air load was proportionally distributed across the slat, wing box and flap in accordance with the obtained aerodynamic calculations using ANSYS CFX. Plots of internal force factors were plotted, such as a diagram of shear force, bending and torque for wing configurations without extended high - lift system, as well as with takeoff and landing positions of high - lift system. Obtaining the value of the internal force factors, were used to create calculation models. The structural elements of the wing, in particular the attachment points of the high - lift system, operate in a complexly stressed state. This complicates the process of predicting the fatigue life of these elements. To obtain a competitive aircraft, it is necessary to develop new methods of wing design with widespread use of integrated systems. The study of the change in the stress-strain state of the wing with the extended position of the high - lift system makes it possible to predict the fatigue life with high accuracy. The process of creating and preparing a wing model for calculation, setting boundary conditions and choosing the optimal size of a mesh element is described. Obtaining aerodynamic characteristics using a CAE system to create a design model.

Mechanical Design of a New Anthropomorphic Robot for Fastening in Wing-Box

The fastener installation in the wing-box faces with narrow space, and it has to be done manually at present. Since manual labor has size constraints, the efficiency is low, and there may be assembly quality instability, it urgently needs automation. Automatic fastening assembly using a robot undoubtedly is an appropriate solution. The existing industrial robots, snake robots, humanoid robots can not meet the fastening assembly requirements in the wing-box. We develop a new anthropomorphic robot with multiple links to perform the inner fastening. A prismatic pair is employed to fit the arm links entering into the wing-box. A shaft with 360 degrees rotation liked human shoulder is introduced to meet the circumferential positioning around the process hole. Arm links are used for robotic end effector reaching the local fastening site. Based on the limitation of assembly position in the wing-box, the link lengths are considered and determined. By using the geometric relation with the link lengths, the joint angle variables are presented. Then, S shape arm link is designed for the compact requirement and the dimensions are determined based on the cross-section of human arm. Finally, stable frame structure is set up through the rear door frame and the bridge beam, and the whole robot is integrated.

Variable geometry wing-box: toward a robotic morphing wing.

The ability to vary the geometry of a wing to adapt to different flight conditions can significantly improve the performance of an aircraft. However, the realization of any morphing concept will typically be accompanied by major challenges. Specifically, the geometrical constraints that are imposed by the shape of the wing and the magnitude of the air and inertia loads make the usage of conventional mechanisms inefficient for morphing applications. Such restrictions have served as inspirations for the design of a modular morphing concept, referred to as the Variable Geometry Wing-box (VGW). The design for the VGW is based on a novel class of reconfigurable robots referred to as Parallel Robots with Enhanced Stiffness (PRES) which are presented in this dissertation. The underlying feature of these robots is the efficient exploitation of redundancies in parallel manipulators. There have been three categories identified in the literature to classify redundancies in parallel manipulators: 1) actuation redundancy, 2) kinematic redundancy, and 3) sensor redundancy. A fourth category is introduced here, referred to as 4) static redundancy. The latter entails several advantages traditionally associated only with actuation redundancy, most significant of which is enhanced stiffness and static characteristics, without any form of actuation redundancy. Additionally, the PRES uses the available redundancies to 1) control more Degrees of Freedom (DOFs) than there are actuators in the system, that is, under-actuate, and 2) provide multiple degrees of fault tolerance. Although the majority of the presented work has been tailored to accommodate the VGW, it can be applied to any comparable system, where enhanced stiffness or static characteristics may be desired without actuation redundancy. In addition to the kinematic and the kinetostatic analyses of the PRES, which are developed and presented in this dissertation along with several case-studies, an optimal motion control algorithm for minimum energy actuation is proposed. Furthermore, the optimal configuration design for the VGW is studied. The optimal configuration design problem is posed in two parts: 1) the optimal limb configuration, and 2) the optimal topological configuration. The former seeks the optimal design of the kinematic joints and links, while the latter seeks the minimal compliance solution to their placement within the design space. In addition to the static and kinematic criteria required for reconfigurability, practical design considerations such as fail-safe requirements and design for minimal aeroelastic impact have been included as constraints in the optimization process. The effectiveness of the proposed design, analysis, and optimization is demonstrated through simulation and a multi-module reconfigurable prototype.

Variable geometry wing-box: toward a robotic morphing wing.

The ability to vary the geometry of a wing to adapt to different flight conditions can significantly improve the performance of an aircraft. However, the realization of any morphing concept will typically be accompanied by major challenges. Specifically, the geometrical constraints that are imposed by the shape of the wing and the magnitude of the air and inertia loads make the usage of conventional mechanisms inefficient for morphing applications. Such restrictions have served as inspirations for the design of a modular morphing concept, referred to as the Variable Geometry Wing-box (VGW). The design for the VGW is based on a novel class of reconfigurable robots referred to as Parallel Robots with Enhanced Stiffness (PRES) which are presented in this dissertation. The underlying feature of these robots is the efficient exploitation of redundancies in parallel manipulators. There have been three categories identified in the literature to classify redundancies in parallel manipulators: 1) actuation redundancy, 2) kinematic redundancy, and 3) sensor redundancy. A fourth category is introduced here, referred to as 4) static redundancy. The latter entails several advantages traditionally associated only with actuation redundancy, most significant of which is enhanced stiffness and static characteristics, without any form of actuation redundancy. Additionally, the PRES uses the available redundancies to 1) control more Degrees of Freedom (DOFs) than there are actuators in the system, that is, under-actuate, and 2) provide multiple degrees of fault tolerance. Although the majority of the presented work has been tailored to accommodate the VGW, it can be applied to any comparable system, where enhanced stiffness or static characteristics may be desired without actuation redundancy. In addition to the kinematic and the kinetostatic analyses of the PRES, which are developed and presented in this dissertation along with several case-studies, an optimal motion control algorithm for minimum energy actuation is proposed. Furthermore, the optimal configuration design for the VGW is studied. The optimal configuration design problem is posed in two parts: 1) the optimal limb configuration, and 2) the optimal topological configuration. The former seeks the optimal design of the kinematic joints and links, while the latter seeks the minimal compliance solution to their placement within the design space. In addition to the static and kinematic criteria required for reconfigurability, practical design considerations such as fail-safe requirements and design for minimal aeroelastic impact have been included as constraints in the optimization process. The effectiveness of the proposed design, analysis, and optimization is demonstrated through simulation and a multi-module reconfigurable prototype.