- Статьи
- Science and technology
- Links of one goal: "controlled destruction" of the landing gear will save passengers in an emergency landing
Links of one goal: "controlled destruction" of the landing gear will save passengers in an emergency landing
Russian engineers have developed a mathematical model that simplifies the calculation of the parameters of the weak link in the landing gear of an aircraft — fasteners that must collapse in an emergency, safely separating the strut from the wing. This solution prevents damage to the fuel tanks, which can lead to a fire or explosion, and reduces the risk of casualties among passengers. The development will help design protective mechanisms for various types of airliners, including the Russian Sukhoi Superjet 100, MS-21 and promising models. In the future, the algorithm is planned to be adapted for other types of equipment. However, before practical application, the model must be confirmed by field tests, experts noted.
How the weak link saves the aircraft
The model created at the Moscow Aviation Institute makes it possible to calculate the forces in the landing gear attachment points of passenger airliners. It allows you to calculate the design parameters in such a way that, in case of critical overloads, the landing gear strut is safely separated from the airframe.
As the developers explained, the algorithm describes the operation of safety structural elements — special hollow mechanical finger bolts. During a hard landing, they are cut off at a pre-calculated location, after which the landing gear elements are separated from the airframe. This helps to prevent damage to the fuel tanks located in the wing of the aircraft, and thereby reduce the risk of an aircraft catching fire when rolling off the runway, rough touching the ground and other emergency situations.
— The landing gear is one of the most important components of an aircraft. It takes enormous loads upon contact with the runway and taxiing. Exceeding the permissible limits may cause the racks to collapse. The task of engineers is to make this process manageable and prevent dangerous consequences," Egor Titov, one of the developers, an engineer of the first category of the Center for Composite Structures, a senior lecturer at MAI, told Izvestia.
Special hollow bolts in the attachment points can help to avoid such scenarios, the scientist explained. They have strictly calculated geometry and strength: they reliably hold the structure in normal operation, and under critical loads they work as a weak link and open it.
At the same time, it is important to remove the detached strut elements from the wing in which the fuel tanks are located. The proposed algorithms make it possible to calculate the parameters with high accuracy and predict the behavior of the structure under such loads, the specialist noted.
Universal algorithms for all airliners
According to Egor Titov, in the study, scientists examined the main types of chassis structures common in the world. We are talking about the schemes used on the Boeing 737 and Superjet 100 aircraft, as well as on the MC-21 and Airbus A320 airliners.
— The essence of the work was to create universal formulas based on standard chassis designs, — he explained. — Such algorithms take into account the geometric features of the design and the calculated forces during landing and, based on them, immediately produce the necessary parameters of the safety elements.
In the future, engineers plan to create an automated method for selecting the parameters of protective parts. The new approach can also be adapted to design other types of equipment.
In particular, we are talking about the driver — tow hitch, which connects the airfield tractor with the landing gear of the aircraft. It also uses shear fingers, which are destroyed if the operator exceeds the permissible angle of rotation.
— A weak link is being laid in the structures of all landing gear supports for passenger aircraft. So, in the import-substituted version, bolted connections with special grooves are designed for the Superjet. There are various methods, both operational and experimental— for calculating such elements. But mathematical models need to be confirmed by field tests, which allow us to see in reality how destruction occurs," Oleg Lukyanov, associate professor at the Department of Aircraft Construction and Design at Samara Korolev University, told Izvestia.
When designing new types of aircraft, including non-standard designs, the approach remains the same, the expert added. However, modern aircraft are increasingly being built using composites. These materials can reduce the weight and increase the bearing capacity of the airframe, but create additional difficulties in designing joints.
In metal structures, holes become sources of stress concentration, but their influence can be reduced due to optimal geometry and local thickening of parts. In composites, when creating holes, the fiber structure is disrupted, which is why they partially cease to perform their supporting function. In general, the behavior of such materials is more difficult to predict, the expert emphasized.
Where else will the development be in demand
— The principle of "weak link" is universal. In particular, it is in demand in the automotive industry, where the entire concept of passive safety is based on controlled destruction. In particular, the use of such links between the battery modules and the body of an electric vehicle suggests itself. This will allow the battery to be instantly isolated in case of an accident and ensure the safety of passengers," says Alexander Kolin, associate professor of the Department of Automobiles and Tractors at the R.E. Alekseev Nizhny Novgorod State Technical University.
According to him, the use of machine learning methods and the creation of specialized software tools can contribute to the development of such technologies. They will allow you to automatically select the parameters of the parts and reduce the amount of routine calculations performed manually.
— The methodology changes the approach to design. Instead of overestimating the static strength of the attachment points, engineers receive a tool for accurately modeling the behavior of the structure under extreme loads. This makes it possible to optimize the mass of the power elements, eliminating the excess safety margin. In addition, the development can accelerate the design of promising airliners," explained Fanil Khabibullin, Associate Professor, Head of the Department of Mechanical Engineering and Engineering Graphics at the Institute of Aviation, Ground Transport and Energy of Kazan National Research Technical University named after A.N. Tupolev.
The expert clarified that in its current form, the algorithm calculates the nominal strength of products, but does not take into account prolonged fatigue loads and vibrations. Due to them, microcracks can accumulate in the bolts, which can lead to premature shearing even with a standard fit. In addition, the calculations must take into account the behavior of the metal during temperature fluctuations. In order to turn the model into a full-fledged tool for practical use, it must be supplemented with operational factors.
Переведено сервисом «Яндекс Переводчик»
