Special Scientific Engineering

Coercimetry NDI of the metal fatigue and its objective priority in the NDE of structures and equipment

  1. Fatigue defects in the metal - a result of its microdamages. Therefore, an objective assessment of state of the metal must be formed from the data on stress-strain (fatigue) condition and its defectiveness. Modern Nondestructive Evaluation is based primarily on information obtained in the process of defect detection operation, because in practice of mass-production nondestructive inspection there is no apparatuses and methods for assessing fatigue.

  2. Today coercimetry, which has a method and apparatus, allows to identify and assess qualitative and quantitative changes in the stress-strain and fatigue condition in a fast, easy and cheap way. This ensures completeness of the raw data of Nondestructive Evaluation. Measurements are performed without cleaning and contact liquid, right through the protective coating thickness of 5-6 mm! Nothing, except fatigue changes in the metal, will make a good coercimeter show rejected defects in the given examination area.

  3. In stress concentration areas accumulation of fatigue microdamages is accelerated, advance. When reaching a certain damage levels (its level by every grade of steel) it already makes sense to perform metal defect detection. Up to this point there are no fatigue defects in the metal. Such sighting and selective approach reduces the volume and cost of Nondestructive Evaluation and its accuracy is improving.

  4. Dimensions of stress concentration areas are substantially of larger size that inevitably appears in these fatigue defects, the location of such zones is not accidental, but is predetermined by the logic design and distribution of applied loads. Therefore fatigue zone, as large and logically arranged, revealed much easier than defects in the metal distributed in them rather randomly.

  5. In the process of examination coercimetry (without damage to the information content) can not be executed completely, but discretely, with step from cm to meters. To refine the boundaries of the degradation and its maximum the measurement step is decreased up to the mm. Step is chosen automatically and always conforms to the task and the state of the metal.

  6. If to perform the coercive force measurements first, as a review, you quickly get general idea of the real current state of the object. Here, stress concentration areas and the degree of degradation of the metal in them are clearly visible at once. This enables us reasonably to apply or not to apply other metal inspection methods depending on the actual fatigue state, including defect detection in all its varieties, but in precisely delineated areas, and volumes.

  7. Numerical coercimetry assessment of degradation of the metal makes up to here hypothetical fatigue control to be checkable, responsible process with accurate quantitative criteria of the degree of fatigue and residual life of the metal. This makes it possible to use the richest apparatus of statistical methods and evaluations, which significantly reduces subjectivity and improves visibility of results display and Nondestructive Evaluation becomes quantitatively measured, proactive and objective, predictive with renewable fatigue data bank of the object and all its elements.

  8. Quantitative evaluation of fatigue state of the metal enables to form an integral numerical characteristic of the state of the whole object as a weighted sum of the same coercimetry numbers that demonstrate fatigue composing its components that make up the object or structural elements. The relative and absolute degree of wear of equipment, the quality of its operation is visible here. On this basis, it is possible to make reasoned decision about priorities, feasibility and scope of the repair, not blindly, but by metal state, exactly within the limits of its unacceptable fatigue damage, rather than by simple welding cracks detection. The most effective operational strategy for the industry, company, workshop, object is forming proving maximal effect of the equipment at minimum expenditures.

  9. Very productive mutually reinforcing combination of coercimetry and thickness gauging in the NDE of metals. If the data of thickness measurements is "bad", but the data of coercimetry is "good" there is no reason to limit the operation of the equipment.