Damage analysis

from Wikipedia, the free encyclopedia

The damage analysis is a systematic procedure for determining the cause of the failure of technical components . The knowledge gained in this way serves to prevent further damage , for example through replacement, inspection and repair of endangered components or targeted changes in construction and / or production . As a result, technical rules (standards) can often be derived with which future damaging events can be reduced or avoided entirely.

Goals of a damage analysis

The primary goal of a damage analysis is to determine the direct cause of damage , which often results in a large number of consequential damage. For example, the failure of an incorrectly produced screw (direct cause of damage, primary damage), which therefore cannot withstand the expected stress, can trigger the crash of a heavy machine part , which causes a lot of further damage (consequential damage, secondary damage). The cause here is the sum of a large number of triggering factors, which all together could only lead to the occurrence of the damage. Influences from production and manufacture , design defects, incorrect material selection, material defects, incorrect dimensioning and unexpected stresses in the operation of the component are often decisive . In addition to the cause, the process and mechanism of the damage are often of interest; the cause often cannot be determined without first investigating and understanding these processes.

In addition to harmless cases of damage, the failure of technical components can lead to accidents in which people are injured or killed. It is all the more important to derive measures to avoid further damage from the cause of the damage. This can be done by changing the inspection intervals during operation of the component and any necessary replacement or, in the case of series parts, it can also lead to large-scale recall campaigns in which the components at risk are preventively replaced with parts that have been modified in construction, are correctly manufactured or are made from a different material.

The knowledge gathered during the damage analysis is often reflected in technical rules that provide assistance to the designers and other people involved in the product development process in order to avoid similar damage in the future, to reduce its frequency or to lessen its strength.

Damage analysis process

In order to be able to carry out a damage analysis successfully, it is very important to plan the procedure carefully by defining the type and scope of the individual investigation steps. Great emphasis must also be placed on the quality of implementation of these. The VDI guideline 3822 "Damage analysis" provides assistance in determining the examination process and defines the terms to be used. This is intended to ensure good comprehensibility and comparability of different damage analyzes by using the same systematic approach.

Description of damage

The first step in the damage analysis is the damage description . The aim is to document the damage pattern, i.e. the appearance, shape and location of the damage. In addition, important structural features and material characteristics should be recorded. The documentation can take the form of photos as well as a verbatim description.

inventory

After completing the description of the damage, the area surrounding the damage is examined more closely in the inventory . In addition to general data such. For example, the manufacturer and age of the defective product are primarily intended to record environmental influences that may have triggered or promoted the damage ( damage history ). These can also be special events that may have occurred before a component failed . The function of the component is also described in the context of the description of the overall system. Data on any damage that may occur more frequently is also important.

Damage hypothesis

With the help of the information gathered so far and the experience of the investigation team, a first damage hypothesis can now be formulated. For this purpose, a probable, hypothetical cause of damage is established from the macroscopically visible damage pattern and the available data , which is to be proven by the subsequent investigations.

Instrumental analysis

On the basis of the established damage hypothesis, an investigation plan is created with which the hypothesis can be proven. For this purpose, studies are also carried out with which the hypothesis can be reliably refuted. All destructive and non-destructive methods of materials testing are used as investigation methods . It is important to plan the sampling process carefully so as not to destroy evidence or to be unable to carry out investigations. It is often helpful to simulate or re-enact the assumed damage process in tests.

Investigation results

The results resulting from the analysis are now used to compare them with the damage hypothesis. If the examinations show clear indications that speak in favor of the hypothesis, the cause of the damage can now be determined with good probability. Often, however, it is also necessary to revise the damage hypothesis based on the findings and to substantiate it with new investigations.

Cause of damage

If the damage hypothesis is viewed as confirmed, the cause of the damage is to be regarded as found. It is documented, broken down into primary and secondary influences of damage.

Damage remedy

From the cause of the damage, measures to prevent further damage or immediately necessary precautions are taken (e.g. recall campaigns).

Report and knowledge management

The damage analysis is then documented in a report that contains all the important information from the previous sub-steps. Appropriate measures ( knowledge management ) continue to ensure accessibility and storage for future use.

literature

  • J. Grosch: Damage science in mechanical engineering. 4th edition. Expert-Verlag, Renningen 2003, ISBN 3-8169-2179-5 .
  • G. Lange: Systematic assessment of technical damage cases. 5th edition. Wiley-VCH, Weinheim 2003, ISBN 3-527-30417-7 .
  • D. Lukowsky: Damage analysis wood and wood-based materials. IRB-Verlag, Stuttgart 2013, ISBN 978-3-8167-8630-6 .
  • Standard: VDI 3822 sheet 1–5 "Damage analysis"