A cyclic cohesive zone model is applied to characterize the fatigue crack growth behavior of a IN718 superalloy which is frequently used in aerospace components. In order to improve the limitation of fracture mechanics-based models, besides the predictions of the moderate fatigue crack growth rates at the Paris’ regime and the high fatigue crack growth rates at the high stress intensity factor <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-0.0498209pt" id="M2" height="8.68572pt" version="1.1" viewBox="-0.0498162 -8.6359 18.3157 8.68572" width="18.3157pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><use xlink:href="#g113-133"/></g><g transform="matrix(.013,0,0,-0.013,8.327,0)"><use xlink:href="#g113-76"/></g></svg> levels, the present work is also aimed at simulating the material damage uniformly and examining the influence of the cohesive model parameters on fatigue crack growth systematically. The gradual loss of the stress-bearing ability of the material is considered through the degradation of a novel cohesive envelope. The experimental data of cracked specimens are used to validate the simulation result. Based on the reasonable estimation for the model parameters, the fatigue crack growth from moderate to high <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-0.0498209pt" id="M3" height="8.68572pt" version="1.1" viewBox="-0.0498162 -8.6359 18.3157 8.68572" width="18.3157pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><use xlink:href="#g113-133"/></g><g transform="matrix(.013,0,0,-0.013,8.327,0)"><use xlink:href="#g113-76"/></g></svg> levels can be reproduced under the small-scale yielding condition, which is in fair agreement with the experimental results.

Huan Li

Jinshan Li

Huang Yuan

Application of a Cohesive Zone Model for Simulating Fatigue Crack Growth from Moderate to High <svg  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"   style="vertical-align:-0.0498209pt" height="8.68572pt" version="1.1" viewBox="-0.0498162 -8.6359 18.3157 8.68572" width="18.3157pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><path id="g113-133" d="M600 0V24L339 665L311 657L43 24V0H600ZM497 50H107L303 539L497 50Z" /></g><g transform="matrix(.013,0,0,-0.013,8.327,0)"><path id="g113-76" d="M743 650H503L496 622L527 618C563 613 564 603 532 573C449 495 371 431 323 392C301 374 272 355 246 346L280 522C297 609 300 614 379 622L385 650H135L129 622C209 614 215 609 198 522L124 133C106 39 99 35 23 28L17 0H271L277 28C193 35 192 39 208 133L239 316C264 328 280 325 303 288C368 183 435 90 502 0H652L659 28C602 34 584 43 543 94C495 154 403 283 347 369L574 554C634 603 659 612 735 624L743 650Z" /></g></svg> Levels of Inconel 718

A novel 3-D unsteady model of in-flight electrothermal deicing process is presented in this paper to simulate the conjugate mass and heat transfer phenomena of water film runback, phase change, and solid heat conduction. Mathematical models of water film runback and phase change are established and solved by means of a loosely coupled method. At the current time step, solid heat conduction, water film runback, and phase change are iteratively solved until the heat boundary condition reaches convergence, then the temperature distribution and ice shape at the moment are obtained, and the calculation of the next time step begins subsequently. A deicing process is numerically simulated using the present model following an icing tunnel experiment, and the results match well with those in the literatures, which validate the present model. Then, an in-flight deicing process is numerically studied to analyze the effect of heating sequence.

Zuodong Mu

Guiping Lin

Xiaobin Shen

Xueqin Bu

Ying Zhou

Numerical Simulation of Unsteady Conjugate Heat Transfer of Electrothermal Deicing Process

This study proposes deployable units driven by elastic hinges and a double-layer hoop deployable antenna composed of these units. A rational modeling method based on the energy equivalence principle is presented to develop an equivalent model of the double-layer hoop antenna in accordance with the structural characteristics of the antenna. The equivalent beam models of the rods with elastic hinges are proposed. The relationship of geometrical and material parameters is established considering the strain energy and the kinetic energy of the periodic unit, which are the same as those of the equivalent beam in the same displacement field. The equivalent model of the antenna is obtained by assembling several equivalent beam models in the circumferential direction. The precision of the equivalent model of the antenna is acceptable as found by comparing the modal analysis results obtained through equivalent model calculation, finite element simulation, and modal test.

Hongwei Guo

Chuang Shi

Meng Li

Zongquan Deng

Rongqiang Liu

Design and Dynamic Equivalent Modeling of Double-Layer Hoop Deployable Antenna

In this research, modal tests and analyses are performed for a simplified and scaled first-stage model of a space launch vehicle using liquid propellant. This study aims to establish finite element modeling techniques for computational modal analyses by considering the liquid propellant and flange joints of launch vehicles. The modal tests measure the natural frequencies and mode shapes in the first and second lateral bending modes. As the liquid filling ratio increases, the measured frequencies decrease. In addition, as the number of flange joints increases, the measured natural frequencies increase. Computational modal analyses using the finite element method are conducted. The liquid is modeled by the virtual mass method, and the flange joints are modeled using one-dimensional spring elements along with the node-to-node connection. Comparison of the modal test results and predicted natural frequencies shows good or moderate agreement. The correlation between the modal tests and analyses establishes finite element modeling techniques for modeling the liquid propellant and flange joints of space launch vehicles.

Chang-Hoon Sim

Geun-Sang Kim

Dong-Goen Kim

In-Gul Kim

Soon-Hong Park

Jae-Sang Park

Experimental and Computational Modal Analyses for Launch Vehicle Models considering Liquid Propellant and Flange Joints

We present various performance trades for multiantenna global navigation satellite system (GNSS) multisensor attitude estimation systems. In particular, attitude estimation performance sensitivity to various error sources and system configurations is assessed. This study is motivated by the need for system designers, scientists, and engineers of airborne astronomical and remote sensing platforms to better determine which system configuration is most suitable for their specific application. In order to assess performance trade-offs, the attitude estimation performance of various approaches is tested using a simulation that is based on a stratospheric balloon platform. For GNSS errors, attention is focused on multipath, receiver measurement noise, and carrier-phase breaks. For the remaining attitude sensors, different performance grades of sensors are assessed. Through a Monte Carlo simulation, it is shown that, under typical conditions, sub-0.1-degree attitude accuracy is available when using multiple antenna GNSS data only, but that this accuracy can degrade to degree level in some environments warranting the inclusion of additional attitude sensors to maintain the desired level of accuracy. Further, we show that integrating inertial sensors is more valuable whenever accurate pitch and roll estimates are critical.

Nathan A. Tehrani

Jason N. Gross

Performance Trades for Multiantenna GNSS Multisensor Attitude Determination Systems

This paper investigates the utilization of differential thrust to help a commercial aircraft with a damaged vertical stabilizer in order to regain its lateral/directional stability. In the event of an aircraft losing its vertical stabilizer, the consequential loss of the lateral/directional stability and control is likely to cause a fatal crash. In this paper, an aircraft with a completely damaged vertical stabilizer is investigated, and a unique differential thrust-based adaptive control approach is proposed to achieve a stable flight envelope. The propulsion dynamics of the aircraft is modeled as a system of differential equations with engine time constant and time delay terms to study the engine response time with respect to a differential thrust input. The proposed differential thrust control module is then presented to map the rudder input to differential thrust input. Model reference adaptive control based on the Lyapunov stability approach is implemented to test the ability of the damaged aircraft to track the model aircraft&#x2019;s (reference) response in an extreme scenario. Investigation results demonstrate successful application of such differential thrust approach to regain lateral/directional stability of a damaged aircraft with no vertical stabilizer. Finally, the conducted robustness and uncertainty analysis results conclude that the stability and performance of the damaged aircraft remain within desirable limits and demonstrate a safe flight mission through the proposed adaptive control methodology.

Long K. Lu

Kamran Turkoglu

Adaptive Differential Thrust Methodology for Lateral/Directional Stability of an Aircraft with a Completely Damaged Vertical Stabilizer

When a carrier-based aircraft is in arrested landing on deck, the impact loads on landing gears and airframe are closely related to landing states. The distribution and extreme values of the landing loads obtained during life-cycle analysis provide an important basis for buffering parameter design and fatigue design. In this paper, the effect of the multivariate distribution was studied based on military standards and guides. By establishment of a virtual prototype, the extended Fourier amplitude sensitivity test (EFAST) method is applied on sensitivity analysis of landing variables. The results show that sinking speed and rolling angle are the main influencing factors on the landing gear&#x2019;s course load and vertical load; sinking speed, rolling angle, and yawing angle are the main influencing factors on the landing gear&#x2019;s lateral load; and sinking speed is the main influencing factor on the barycenter overload. The extreme values of loads show that the typical condition design in the structural strength analysis is safe. The maximum difference value of the vertical load of the main landing gear is 12.0&#x0025;. This research may provide some reference for structure design of landing gears and compilation of load spectrum for carrier-based aircrafts.

Jin Zhou

Jianjiang Zeng

Jichang Chen

Mingbo Tong

Analysis of Global Sensitivity of Landing Variables on Landing Loads and Extreme Values of the Loads in Carrier-Based Aircrafts

During countersunk hole machining, defects like geometrical deviation of the chamfer angle and delamination are easily introduced into the structure. To investigate the influences of geometrical deviation on delamination propagation around the countersunk hole during assembly, a progressive damage model (PDM) combining cohesive element was proposed and validated. Numerical analyses were then carried out to study delamination propagation behavior under the influences of geometrical parameters including delamination factor, chamfer angle, and location of delamination. The results show that when delamination appears at the transition area of the countersunk hole, the load causing the delamination evolution is much smaller than other cases.

Xueshu Liu

Yuxing Yang

Li Huang

Ping Zhang

Hang Gao

Numerical Analysis of the Influences of Geometrical Deviation on Delamination in Composite Laminates around the Countersunk Hole

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<p><em>International Journal of Aerospace Engineering </em>serves the international aerospace engineering community through the dissemination of scientific knowledge on practical engineering and design methodologies pertaining to aircraft and space vehicles.</p>


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<p>Chief Editor, Professor Zhao, is based at the University of Canterbury and his research interests include applying theoretical, numerical and experimental approaches to study combustion instability, thermoacoustics and aerodynamics.</p>


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International Journal of Aerospace Engineering | Hindawi

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International Journal of Aerospace Engineering serves the international aerospace engineering community through the dissemination of scientific knowledge on practical engineering and design methodologies pertaining to aircraft and space vehicles.

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International Journal of Aerospace Engineering

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International Journal of Aerospace Engineering