In the product development process designs are often exposed to an outdoor environment for an extended period or corrosion acceleration tests are conducted to simulate the actual condition the vehicle or structure will be exposed to during its life. These methods however require several months to several years of test time to complete. Computer modelling has the potential to significantly shorten and reduce the cost of testing by substituting for long term exposure and corrosion acceleration testing. Galvanic corrosion (GC) occurs when different materials are in contact with a common electrolyte. GC on its own can cause severe damage in a structure due to highly accelerated corrosion rates compared to other mechanisms. Usually GC can be avoided by proper material selection and appropriate corrosion protection measures. However, combinations of dissimilar materials are often applied due to structural requirements that need to be fulfilled in the design. In this case, costly corrosion prevention systems have to be applied to avoid the access of electrolyte. Often, GC alone may not be directly the main cause of structural failures, but its occurrence may favour proper conditions for initiation of other types of corrosion such as pitting.
Until the end of the 60’s no significant attention was given to corrosion in the aircraft industry and many other manufacturing industries. Thereafter manufacturers and engineers became increasingly aware of the impact of different types of corrosion on the lifetime of the structures and it was estimated a few years ago that the cost in the United States alone costs was estimated to be of the order of 2.2 billion dollars per year. Nowadays, different forms of corrosion (i.e. galvanic, pitting, crevice, inter-granular, etc.) are generally recognised as key factors in limiting the operational life time of the aircraft because of uneconomical high maintenance but the major contributor to corrosion damage is however galvanic corrosion.
In other industries such as automotive the drive towards lighter vehicles has required the substitution of steel by lighter materials such as aluminium and magnesium. However the combination of these materials when exposed to the harsh corrosive environment typically found in vehicles can lead to significant galvanic corrosion. In the product development process designs are often exposed to an outdoor environment for a long time, or corrosion acceleration tests are conducted to simulate the actual condition the vehicle will experience on the road. These methods however require several months to several years of test time to complete. Computer modelling has the potential to significantly shorten and reduce the cost of testing by substituting for long term exposure and corrosion acceleration testing.
BEASY Corrosion Manager
BEASY Corrosion Manager Software enables engineers to quickly assess the risk to components and structures of corrosion and the effectiveness of surface protection systems. Galvanic Corrosion is important as it occurs whenever dissimilar metals or certain types of composites (e.g. carbon based) are located close to each other. The geometry of the connections, the characteristics and extent of the electrolyte and the type of mitigation methods employed affect the extent and rate of corrosion. BEASY Corrosion Manager Simulation enables engineers to replace the “find it and fix it” approach and replace it by a more fundamental approach based on an understanding of the corrosion process and the ability to predict its behaviour.
Simulation Of Corrosion & Fracture Damage
Structures regularly operate in environments that can cause high levels of corrosion damage, and this damage leads to stress concentrations within the structure and potential development of cracks. Even when only a thin film of electrolyte is present on the structure, this can still lead to an electrical field that causes surface damage.
Computation of this electrical field can be used to identify areas in the structure that are most susceptible to corrosion damage and which, after fatigue crack initiation, may lead to structural failure. Corrosion simulation can be used to take account of the properties of the electrolyte as well as the structural materials, to determine the rate of material loss from the structure.
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