Aircraft Vertical Tail Research Articles

A Data-Driven Machining Error Analysis Method for Finish Machining of Assembly Interfaces of Large-Scale Components

Abstract To guarantee the final assembly quality of the large-scale components, the assembly interfaces of large components need to be finish-machined on site. Such assembly interfaces are often in low-stiffness structure and made of difficult-to-cut materials, which makes it hard to fulfill machining tolerance. To solve this issue, a data-driven adaptive machining error analysis and compensation method is proposed based on on-machine measurement. Within this context, an initial definite plane is fitted via an improved robust iterating least-squares plane-fitting method based on the spatial statistical analysis result of machining errors of the key measurement points. Then, the parameters of the definite plane are solved by a simulated annealing-particle swarm optimization (SA-PSO) algorithm to determine the optimal definite plane; it effectively decomposes the machining error into systematic error and process error. To reduce these errors, compensation methods, tool-path adjustment method, and an optimized group of cutting parameters are proposed. The proposed method is validated by a set of cutting tests of an assembly interface of a large-scale aircraft vertical tail. The results indicate that the machining errors are successfully separated, and each type of error has been reduced by the proposed method. A 0.017 mm machining accuracy of the wall-thickness of the assembly interface has been achieved, well fulfilling the requirement of 0.05 mm tolerance.

Co-design of aircraft vertical tail and control laws with distributed electric propulsion and flight envelop constraints

A sequential co-design framework has been developed in a previous study (Nguyen-Van et al., IFAC-PapersOnLine 52(12):514–519, https://doi.org/10.1016/j.ifacol.2019.11.295 , 2019)) to design an aircraft using active differential thrust. Differential thrust is used instead of a rudder to generate the yawing moment. The objective is to dimension in parallel the vertical tail surface area, the electric motor bandwidth and control laws while maintaining imposed handling qualities. This paper focuses on the development of a single step co-design taking into account handling qualities, flight envelop requirements and motor saturation. Additional and compatible optimisation constraints are found based on a sensitivity analysis. It reveals the importance of electric motor bandwidth with respect to aircraft natural stability. The direct co-design leads to an optimised trade-off between vertical tail and electric motor bandwidth.

Force Analysis of Fork Type Connecting Structure Pin Roll of Aircraft Vertical Tail in Comprehensive State

Aiming at the stress problem of pin roll connection at the vertical tail of aircraft, the thesis establishes a simplified simulation model of vertical tail. From the mechanical perspective, it takes into account the gravity, assembly force of interference fit and the influence of air resistance on the fork force. Compared with the yield stress of titanium alloy material used in the actual fork, it is concluded that actual stress is much smaller than the yield stress of the material, which verifies the rationality of pin roll design.

Eddy Current-Based Vibration Suppression for Finish Machining of Assembly Interfaces of Large Aircraft Vertical Tail

Assembly interface of aircraft vertical tail is a large thin-wall structure and made from titanium alloys, which causes easily machining vibration, deformation and undercutting in finish machining due to its low stiffness, low thermal conductivity, and high chemical activity. To address these problems, a novel eddy current damper for assembly interfaces machining (ECD-AIM) is proposed to suppress multimodal vibration in the machining of the assembly interfaces. Within the context, the mathematical model of damping performance of the damper is established based on the principle of electromagnetic induction, based on which a novel design of the damper is proposed, and optimized by considering the relationship between damping performance and the key components of the damper. Then, the dynamics model of the suppression system of the assembly interface machining is established, where the relationship between vibration velocity and damping performance of the damper is obtained by using numerical analysis and finite element simulation. Finally, the damping performance of the damper is validated in terms of the three configurations (no applied ECD-AIM, a single ECD-AIM, and dual ECD-AIMs) via a set of dynamic tests (impact tests and harmonic tests) and cutting tests. The test results demonstrate that the configuration of dual ECD-AIMs can guarantee stability and reliability of assembly interface machining. The proposed damper can provide a feasible solution for vibration suppression in a limited workspace.

Co-design of aircraft vertical tail and control laws using distributed electric propulsion

Abstract Distributed Electric Propulsion is investigated as a way to increase directional control of aircraft and reduce the vertical tail surface area. A co-design approach is presented where a H∞ control method is used to both synthesize longitudinal/lateral control law gains and allocation module while sizing the vertical tail surface area and the propeller actuator bandwidth. The variation of the vertical tail surface area is captured throughout a collection of linearized aircraft systems representing different sizes of the vertical tail reassembled in a Linear Fractional Representation. This approach allows a reduction of 60% of the vertical tail surface area while maintaining desired dynamic behaviors with low actuator bandwidth.

激光沉积修复某型飞机垂尾梁研究

激光沉积修复某型飞机垂尾梁研究

激光沉积修复某型飞机垂尾梁研究

激光沉积修复某型飞机垂尾梁研究

Operator-based experimental studies on nonlinear vibration control for an aircraft vertical tail with considering low-order modes

In this paper, a robust nonlinear control design using an operator-based robust right coprime factorization approach is considered for vibration control on an aircraft vertical tail with piezoelectric elements. First, a model of the aircraft vertical tail is derived to describe vibration response using the operator-based approach, where, to stabilize vibration of the tail, piezoelectric elements are used as actuators and a hysteresis nonlinear property of piezoelectric actuators is considered. Simultaneously, positions of the piezoelectric actuators that are stuck on the plate are arranged by using a finite element method. Then based on the obtained operator-based model, a robust nonlinear feedback control design is given by using robust right coprime factorization for the aircraft vertical tail with considering the effect of hysteresis nonlinearity from piezoelectric actuators. In particular, low-order modes are employed to design the control scheme even though vibration is configured by high-order modes. In other words, robustness is considered, and the desired performance of tracking is discussed. Finally, both simulation and experimental results are shown to verify the effectiveness of the proposed control scheme.

Effect of Enlarging the Aircraft Vertical Tail on State Variables of Stability Response during Dynamic Coupling

In this paper the variables of high performance aircraft including the modification of vertical tail during the roll inertia cross coupling phenomenon is presented. To demonstrate the effects of the enlarging the area of vertical tail on stability of aircraft, the longitudinal-lateral equations of aircraft motion at steady roll rate are solved. The results indicate that damping of the modified system is increased and the longitudinal-lateral state variables response of the aircraft is improved. The increase in the area of the vertical fin is a necessary feature in the development of the aircraft to improve stability during roll and decrease the possibility of cross coupling occurrence. Also the results indicated that the critical value of roll rate in case 1,at Mach no.=0.6, takes the range of ,while the values of critical roll rates in case 2,3 and 4 are , , ,Respectively. The numerical results shows 19% , 15.5% , and 15% gain in rolling margin for cases 2, 3, and 4 respectively, when compared with original (case 1) .

Research on Bird Strike Simulation of Composite Leading Edge

The paper studies the bird strike against composite material tail leading edge under Chinese HB7084-94 condition, including material failure process, by using explicit finite element method. SPH grid free method is taken to describe birds splashing during the strike. The calculation results show that, the original design composite structure could not meet the requirements of standard HB7084-94 towards the aircraft vertical tail anti-bird impact performance. The optimized design increases the ply number of the leading edge from 6 to 22. With a weight cost of 2.957Kg, the optimized design could meet the standard.

A Blending Control Aircraft Assembly Quality Method Using Key Assembly Characteristic

Assembly quality control is the main problem concerned by assembly departments in aircraft industry. This paper discusses the key assembly characteristics (KACs) which are the critical dimension characteristics for assembly quality in details, and then proposes a mathematical method which consists of identification and blending control method (BCM) towards KACs. BCM includes tightening tolerance and compensation, which can quantitatively control the KACs determined by validating error stack-up. A demonstration is given to verify the validity of the proposed method by controlling the assembly quality of an aircraft vertical tail.

Design "Feasilization" Using Knowledge-Based Engineering and Optimization Techniques

The multidisciplinary design optimization process can be supported by partial automation of analysis and optimization steps. Design-and-engineering engines are a useful concept to structure this automation. Within the design-and-engineering engines, a product is parametrically defined using knowledge-based engineering. This parametric product model needs to be initiated before global multidisciplinary optimization can be performed. The 'feasilization is done by the initiator component in the design-and-engineering engines that simulates the heuristic methods normally used by designers to estimate the first values for the parameters and variables describing their designs. The initiation of values for structural parameters and variables is elaborated for a sample composite-stiffened panel structure. It is shown that the initiator function of the design-and-engineering-engine concept can be implemented on the basis of optimization techniques using simplification of the design requirements, simplified representations of the design options, and the class of so-called schematic models to mimic the designer's job in the preliminary sizing phase of the design. An implementation of the initiator is used in a sample design-and-engineering engine for aircraft vertical tail design.