Landing Gear as an Essential Subsystem of an Aircraft - Case Study Example

Vibration analysis of Аirсrаft landing gеаr Name Institution Vibration analysis of Аirсrаft Landing Gеаr Article 1 Divakaran, RaviKumar and Srinivasa (2015) assert that a landing gear is an essential subsystem of an aircraft and should therefore be made at the best quality level to allow proper functioning of an aircraft. Due to its considerable influence on the structural configuration of an aircraft, the landing gear is usually configured alongside the aircraft structure. As a result of the long product development cycle of the landing gear, its design is taken up early enough in design process. According to Divakaran, RaviKumar and Srinivasa (2015), a landing gear has various components. Some of the structural components are shock absorber, axle, up lock, main fitting and wheel among others. On the other hand, the system components include antiskid system, brake unit and retraction system elements. The design and development cycle of a landing gear comprises of the following stages; concept design, preliminary design, detailed design, stress and fatigue analysis, reliability and maintainability analysis, manufacturing and assembly, qualification testing, on-aircraft testing, and finally in-service evaluation. The landing gear plays a critical role in an aircraft. It offers a suspension system during crucial moments; taxi, take-off as well as landing time. In an effort to minimize the impact loads passed on their airframe, the landing gear is designed in such a way that it absorbs and dispels the kinetic energy of landing impact. Another role is facilitating braking of the aircraft. This is made possible by the use of a wheel braking system. On the other hand, a wheel steering system is used to give directional control of the plane on ground. In order to reduce the aerodynamic drag on the plane during flying, the landing gear is made retractable (Divakaran, RaviKumar & Srinivasa, 2015). According to Divakaran, RaviKumar and Srinivasa (2015), there are many challenges that are associated with the design of a landing gear. There is a need to balance attributes of the landing gear while at the same time ensuring that the gear functions appropriately. For instance, a good landing gear should possess the following characteristic. It should have minimum volume and weight, be of high performance and enhanced life as well as minimized life cycle cost. Another essential attribute is observing all the safety and regulatory requirements, an aspect that may prolong the design and development cycle duration of the landing gear. Under all circumstances, the design of the landing gear should adhere to different requirements of stiffness, stability, damping, ground clearance and strength. All these allow the aircraft to meet both safety and operational requirements. Divakaran, RaviKumar and Srinivasa (2015) indicate that to deal with the above challenges, various advanced technologies have been devised. Appropriate materials as well as analysis, processes and production methods are also employed to overcome the challenges. The challenges have also necessitated the development of a variety of design and analysis tools. Some of the technologies that have been developed in order to manage the challenges include advancement in steering control systems whereby the hydro-mechanical systems are being replaced by electronic control systems. This enhances accuracy and allows for easy incorporation of changes in design considerations. With regard to actuation systems, the conventional hydraulic systems are being replaced by electric systems, which are weight sensitive and help deal with challenges of leakage and fire hazard. In addition, electronic antiskid brake management systems are now used instead of mechanical systems, thus enhancing efficiency. Replacement of bias ply tires with radial tire is a technological advancement with great benefits. Higher reliability proximity switches and hydro-mechanical locking systems are also replacing micro-switches and mechanical locks. The materials used have also improved with respect to quality. For instance, composites are used in some parts of the landing gear due to their greater stiffness and strength attributes. For corrosion protection, corrosion resistant materials are being used. This is because landing gear components are highly vulnerable to environment attack. CAX technologies have also found great application in the design and development of the landing gear. This includes software tools that have allowed for virtual development of the landing gear way before the actual prototype is constructed. In turn, this enhances designs and minimizes on the cost as well as cycle time. There is also the development of information intelligence and knowledge based engineering tools. They help in the automation of different engineering processes. Some of the benefits involved include minimal human errors and reduced development cycle time among others. Dynamic simulation is also a technology that has helped improve the landing gear performance. It assists in the prediction of the performance of a given component and thus makes necessary adjustments. Health monitoring of the landing gear is also an advancement that has greatly enhanced its performance in terms of safety (Divakaran, RaviKumar & Srinivasa, 2015). It also reduces maintenance and operational costs. Article 2 A research by Sateesh and Maiti (2010) indicates that there is more when it comes to nose landing gear and vibration control with respect to excitation that is ground-induced. Runway unevenness is an aircraft a critical aspect when it comes to the design and operation of any aircraft. This is more so because it generates lateral as well as longitudinal excitations. A little amount of runway excitation is in a position to lead to a considerable decrease in the crucial shimmy velocity. When free play is added to the excitation, adverse effect is experienced on the tangential steadiness of the nose landing gear of a plane. According to Sateesh and Maiti (2010), surface unevenness is a contributing factor to random base excitations for motor vehicles moving on the ground. Prepared surfaces such as aircraft runway, roads and railway tracks are usually uneven. The unevenness can generate considerable tangential excitation on the landing gear of a plane, an aspect that negatively affects its lateral stability. As a way of assessing the landing gear system for aspects such as response and stability, it is advisable to come up with system components that are capable of capturing the contributions of various attributes. These include the landing gear structure, its interaction with the runway, the tyre and wheel configuration as well as system non-linearities among others. Sateesh and Maiti (2010) assert that an airliner landing gear structure should at all times be in a position to absorb the kinetic energy that is usually generated by a landing force as well as the movements associated with an airliner roving over an jagged runway ground. It is an aspect that should always be considered in the design and development of a landing gear system. The research indicated that ground profiles are typically irregular and continuous. For this reason, modelling of the ground profile is a significant requirement when it comes to simulation of system response. Another observation that is worth noting is that aircraft gears are often susceptible to many self-exited oscillations as well as ground-induced vibrations or external excitations. This has the effect of bringing about conflicting damping requirements. However, there is a solution to this problem. The damping should be executed using a damper that is based on magneto rheological (MR) fluid. The damper is in a position to produce the magnitude of convenient damping forces that are a necessity for full scale applications, while at the same time needing just a battery for its power. The damper helps in improving stability of the nose landing gear of an aeroplane. The damper has proved to be a superior and a relatively active tool and suitable for use for managing vibration of landing gear structure. It is also worth noting that the decrease in critical velocity as a result of airstrip movement is influenced by the irregularity of the runway. Also, improved torque wing rigidity could prevent the vibration setback, associated with the swiftness during take-off (Sateesh & Maiti, 2010). Sateesh and Maiti (2010) argue that an MR damper is quite an essential element in controlling vibration of a plane nose landing gear, resulting from thrill induced by the ground. Some of the major components of an MR damper include; fins, piston assembly, O-ring supports, cylinder and cover plate as well as corresponding dimensions among others. Based on how significant an MR damper is, it is important to have a deep understanding of its modelling. A normal replica of a finned MR damper could have a cylinder and a piston as the main components. To produce a magnetic field, wire made of is coiled over the fins. The coil assembly could be permanent and the housing of the damper is in a position to rotate. Liquid is put via the opening available between the coil assembly and the damper housing and it may be triggered by the magnetic field. The comparative rapidity between the cylinder and the piston results to an express means of operation and produces a damping energy. The use of a torsional MR damper as a complementary device is one of the fruitful ways that can be used in the control of the unwanted vibrations in the aircraft’s nose landing gear and should therefore be considered if success is to be achieved. This will ensure that the negative effects associated with the vibrations are avoided (Sateesh & Maiti, 2010). The evaluation of the shimmy phenomenon associated with the nose landing gear is quite essential. This is made possible through the assessment of the tangential reaction of nose landing gear to ground commotion. The interaction of the landing gear with torsional free play is also a significant factor of consideration. References Divakaran V.N., RaviKumar G.V.V. & Srinivasa R. P. (2015). Aircraft landing gear design & development- How advanced technologies are helping to meet the challenges? Infosys. Sateesh, B., & Maiti, D. K. (2010). Vibration control of an aircraft nose landing gear due to ground-induced excitation. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 224(3), 245-258. Read More

This includes software tools that have allowed for virtual development of the landing gear way before the actual prototype is constructed. In turn, this enhances designs and minimizes on the cost as well as cycle time. There is also the development of information intelligence and knowledge based engineering tools. They help in the automation of different engineering processes. Some of the benefits involved include minimal human errors and reduced development cycle time among others. Dynamic simulation is also a technology that has helped improve the landing gear performance.

It assists in the prediction of the performance of a given component and thus makes necessary adjustments. Health monitoring of the landing gear is also an advancement that has greatly enhanced its performance in terms of safety (Divakaran, RaviKumar & Srinivasa, 2015). It also reduces maintenance and operational costs. Article 2 A research by Sateesh and Maiti (2010) indicates that there is more when it comes to nose landing gear and vibration control with respect to excitation that is ground-induced.

Runway unevenness is an aircraft a critical aspect when it comes to the design and operation of any aircraft. This is more so because it generates lateral as well as longitudinal excitations. A little amount of runway excitation is in a position to lead to a considerable decrease in the crucial shimmy velocity. When free play is added to the excitation, adverse effect is experienced on the tangential steadiness of the nose landing gear of a plane. According to Sateesh and Maiti (2010), surface unevenness is a contributing factor to random base excitations for motor vehicles moving on the ground.

Prepared surfaces such as aircraft runway, roads and railway tracks are usually uneven. The unevenness can generate considerable tangential excitation on the landing gear of a plane, an aspect that negatively affects its lateral stability. As a way of assessing the landing gear system for aspects such as response and stability, it is advisable to come up with system components that are capable of capturing the contributions of various attributes. These include the landing gear structure, its interaction with the runway, the tyre and wheel configuration as well as system non-linearities among others.

Sateesh and Maiti (2010) assert that an airliner landing gear structure should at all times be in a position to absorb the kinetic energy that is usually generated by a landing force as well as the movements associated with an airliner roving over an jagged runway ground. It is an aspect that should always be considered in the design and development of a landing gear system. The research indicated that ground profiles are typically irregular and continuous. For this reason, modelling of the ground profile is a significant requirement when it comes to simulation of system response.

Another observation that is worth noting is that aircraft gears are often susceptible to many self-exited oscillations as well as ground-induced vibrations or external excitations. This has the effect of bringing about conflicting damping requirements. However, there is a solution to this problem. The damping should be executed using a damper that is based on magneto rheological (MR) fluid. The damper is in a position to produce the magnitude of convenient damping forces that are a necessity for full scale applications, while at the same time needing just a battery for its power.

The damper helps in improving stability of the nose landing gear of an aeroplane. The damper has proved to be a superior and a relatively active tool and suitable for use for managing vibration of landing gear structure. It is also worth noting that the decrease in critical velocity as a result of airstrip movement is influenced by the irregularity of the runway. Also, improved torque wing rigidity could prevent the vibration setback, associated with the swiftness during take-off (Sateesh & Maiti, 2010).

Sateesh and Maiti (2010) argue that an MR damper is quite an essential element in controlling vibration of a plane nose landing gear, resulting from thrill induced by the ground.

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