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ADLAND
Adaptive Landing Gears for Improved Impact Absorption

Background

The motivation for this research is to respond to requirements for high impact energy absorption in landing gears. Typically, shock absorbers are designed as passive devices with characteristics adjusted either to the most frequently expected impact loads or to ultimate load conditions. However, in many cases the variation of real working conditions is so high that the optimally designed passive shock absorber does not perform well enough.

In contrast to the passive systems, the proposed research focuses on active adaptation of energy absorbing structural elements, where a system of sensors recognises the type of impact loading and activates energy absorbing components in a fashion that guarantees optimal dissipation of impact energy.

Project objectives

The project objectives are:

  • to develop a concept of adaptive shock-absorbers
  • to develop new numerical tools for the design of adaptive vehicles and for the simulation of the adaptive structural response to an impact scenario
  • to develop technology for actively controlled shock-absorbers applicable in landing gears (there are two options: Magneto-Rheological Fluid-based (MRF) and Piezoelectric Valve-based).
  • to design, model and perform repetitive impact tests of the adaptive landing gear model with high impact energy dissipation effects
  • to design, produce and test in flight the chosen full-scale model of the adaptive landing gear.
Load on the active landing gear prototype in comparison with a load on a passive landing gear.
Load on the active landing gear prototype in comparison with a load on a passive landing gear.

Description of the work

Work Package 1: Description of the state-of-the-art. Analysis of statistics and specification of life-cycle requirements. Determination of hardware/software requirements for adaptive shock-absorbers. Definition of necessary safety aspects to be considered.

Work Package 2: Development of methodology and the corresponding software tools for simulation of adaptive landing scenarios. Development of software tools for modelling and design of adaptive shock absorbers (Piezo- and MRF-based). Creation of numerical models and computer simulations for case studies. Design of magnetic circuits for MRF-based shock-absorbers and the design of MRF-based shock absorber. Design of Piezo-valves, fluidic circuits, driving electronics and the complete PD -based shock absorber. Design of landing gear shock absorbers using 3D CAD systems (Solid Edge and Nastran systems) and test equipment.

Work Package 3: Elaboration of sensing system for impact prediction, detection and identification (software and hardware). Fabrication of real-time controller for shock absorbers. Design and fabrication of MRF and Piezo-valve based lab-scale models of shock absorbers. Fabrication of full-scale model of adaptive shock absorber. ALG system integration (software, hardware and driving electronics). Hardware controller fabrication.

Work Package 4: Evaluation of the requirements from the ALG to the MR fluid properties. Characterisation of application-relevant MR fluid properties like base viscosity, field-dependent shear stress, temperature behaviour, sedimentation stability, etc. Development of an MR fluid adapted to the requirements of the ALG. Development of specific testing procedures, which are necessary to evaluate the MR fluid behaviour for use in the ALG. Supply of MR fluid in quantities of some litres for tests in the shock absorbers.

Work Package 5: Small lab tests with MRF and Piezo-valve based shock-absorbers. Full-scale lab tests with landing gear equipped with MRF and/or Piezo-valve based shock absorbers. Validation of the real-time control techniques. Verification of software tools vs. experiment.

Work Package 6: Flight testing. Evaluation of flight test results.

Expected results

1. Specifications determined in Work Package 1 will be used as the starting point in further Work Packages.

2. The control part of the software will be used as an ALG controller in lab-tests

3. Software-hardware integration will be made after lab-tests. Hardware controller will be manufactured. Decision about the most promising ALG technology will be taken.

4. MR fluid with the desired properties will be produced and supplied for testing in lab-testing installations and in full-scale models

5. The control software (installed in notebook) and ALG hardware will be tested. After positive verification vs. experiment, integration of the ALG system will be made and the hardware controller will be produced. Decisions concerning ALG hardware will be made

Black line: low impact energy, passive shock absorber Blue line: low impact energy, active shock absorber Red line: high impact energy, passive shock absorber Green line: high impact energy, active shock absorber
Black line: low impact energy, passive shock absorber
Blue line: low impact energy, active shock absorber
Red line: high impact energy, passive shock absorber
Green line: high impact energy, active shock absorber

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