SHM Supporting Damage Tolerance Design Philosophy As a Challenge for Designers of Future Airframes
Development design pfilosophy of airframes in all the relevant technological fields is important for the evaluation of high performance airframes best to achive high level of safety and satisfy the market needs. Maintenance cost reduction, increased aircraft availability and weight saving are goals which will be reaching by SHM systems as on-line monitoring of the structure health. Irrespective of which materials will be used in the future, the current design philosophy, which is applied today by the structural designers, will be challenged by the new design philosophy based on SHM. The most efective SHM methods are based on Lamb wave techniques. Using the based on Lamb wave techniques would be cost-effective and reliable damage detection is critical for the utilization of metal, composite and hybrid materials. Multitude of diagnostics data requires to use expert systems for effective analysis.
During its operation, the laminate shell of the watercraft hull can be exposed to local stability losses caused by the appearance and development of delaminations. The sources of these delaminations are discontinuities, created both in the production process and as a result of bumps of foreign bodies into the hull in operation. In the environment of fatigue loads acting on the hull, the delaminations propagate and lead to the loss of load capacity of the hull structure. There is a need to improve diagnostic systems used in Structural Health Monitoring (SHM) of laminate hull elements to detect and monitor the development of the delaminations. Effective diagnostic systems used for delamination assessment base on expert systems. Along with other tools, the expert diagnostic advisory systems make use of the non-destructive examination method which consists in generating elastic waves in the hull shell structure and observing their changes by comparing the recorded signal with damage patterns collected in the expert system database. This system requires introducing certain patterns to its knowledge base, based on the results of experimental examinations performed on specimens with implemented artificial delaminations. The article presents the results of the examination oriented on assessing the delaminations artificially generated in the structure of glass- and carbon-epoxy laminates by introducing local non-adhesive layers with the aid of thin polyethylene film, teflon insert, or thin layer of polyvinyl alcohol. The efficiency of each method was assessed using laser vibrometry. The effect of the depth of delamination position in the laminate on the efficiency of the applied method is documented as well.
Safety of Operation and Maintenance Systems of Aircraft Fleet
The flight of on aircraft has been realzed I on operational subsystem. The operation of on aircraft and its safeability are determined for aircraft fleet the so-called flight safety. Aircraft operation and its safeability determine the flight safety of aircraft fleet. The flight safety can be modelled, condition diagnosed, put the procedures of genesis and prognosis. As the results of these activities the prevention treatments can be worked out. A aircraft safety, air system safety or air safety can be considered. Within the flight safety science.
The paper presents forward-looking approach to airframe design and development by integrated design philosophy with the philosophy of sustainability management service in terms of quality, taking into account the whole life cycle of the aircraft and the interactions between the different phases. The approach has been presented pro-quality. The determinants of quality and relationships has been identified. The concept of an advisory system logistics support airframe design using artificial intelligence methods.
The paper proposes a selected key issues in the efficient formation of the airframe structure. The issues of concern design lifetime, manufacturing, command of the durability proposed in the accelerated tests and management of sustainability in the operation. A key importance is of the creating a durability of the airframe, which affects to choice materials and construction solutions. A key problem is modeling the system of exploitation and the inclusion of all the factors influencing the persistence in the aspect of aviation regulatory requirements. A key area influencing the prevention after air accidents, causes by loss of structural coherence of the airframe macroscopic structure. A key importance is the use of accelerated durability testing. A key issue is to determine if the concept of durability and viability are separate or similar in characteristics of durability. The key is to determine the diamonds of quality. A key importance is attributed to diagnostics, including integrated to airframe structure, defining a continuous condition of the aircraft through research pre-fault symptoms. These studies provide the knowledge which determines prevention activities.
The paper defines the essence of durability characteristics of the designing structure of an airframe in terms of flight safety. Particular attention is drawn to one of the main factors influencing the durability characteristics of the airframe – diagnostics system for the health assessment of the airframe during the process of operation. The effectiveness of the use of integrated solutions to the structure of the airframe providing a continuous assessment of the technical condition is presented. Continuous diagnostics system integrated with the airframe, SHM, is classified as an intelligent solution. This paper presents a model of the behavior of one-type aircraft operating in the air operator’s fleet in terms of susceptibility to failure. Justified assumption in the description of this behavior, in the form of a “bathtub curve”. The analysis is supported by real data of failures. The benefits of using a continuous diagnostics system integrated with the airframe, SHM, is interpreted in relation to the classical approach with the use of non-destructive testing, NDT, for the three phases of the bathtub curve.
This paper presents the procedure to be followed in order to determine the optimal time of non-repair component of the air operator's aircraft fleet. This problem is very important because of the losses that may occur as a result of too late the decision to replace and the damaged might occur during the operation of the airplane. On the other hand, the operator suffers losses because of too frequent replacements. These losses are generated by very early replacement of the efficient equipment and in addition generate excessive workload sharing on its assessment, the impact of human factors and increase the aircraft downtime. There is thus an optimal solution for which the objective function is to maximize the technical and operational readiness expressing the ratio of aircraft downtime and the time of its use as intended uptime with minimal costs. The optimal condition for the data component of the failure rate was determined and presented in this paper. The resulting replace component of the optimal interval must then be correlated with other work to do on an airplane as Maintenance Programme - MP.