Types of Testing

Types of Testing: there are two main types of tests:
1. Destructive testing
2. Nondestructive testing
Nondestructive Testing
In certain applications, the evaluation of engineering materials or structures without impairing their properties is very important, such as the quality control of the products, failure analysis or prevention of the engineered systems in service. This kind of evaluations can be carried out with non destructive test (NDT) methods. It is possible to inspect and/or measure the materials or structures without destroying their surface texture, product integrity and future usefulness. These methods can be performed on metals, plastics, ceramics, composites, cermet, and coatings in order to detect cracks, internal voids, surface cavities, incomplete defective welds and any type of flaw that could lead to premature failure.
A general definition of nondestructive testing (NDT) is an examination, test, or evolution performed on any type of test object without changing or altering that object in any way, that can provide useful information regarding the condition of the object being examined, approved procedures are followed, and the examinations are conducted by qualified personnel in order to determine the absence or presence of conditions or discontinuities that may have an effect on the usefulness or serviceability of that object. Nondestructive tests may also be conducted to measure other test object characteristics, such as size; dimension; structure, including alloy content, hardness, grain size, etc. Nondestructive examination (NDE), nondestructive inspection (NDI), and nondestructive evaluation (NDE) are also expressions commonly used to describe this technology.
Although NDT cannot guarantee that failures will not occur, it plays a significant role in minimizing the possibilities of failure. Other variables, such as inadequate design and improper application of the object, may contribute to failure even when NDT is appropriately applied.
Nondestructive testing, in fact, is a process that is performed on a daily basis by the average individual, who is not aware that it is taking place.
The human body has been described as one of the most unique nondestructive testing instruments ever created. all the human senses, the sense of sight provides us with the most versatile and unique nondestructive testing approach. When one considers the wide application of the sense of sight and the ultimate information that can be determined by mere visual observation, it becomes quite apparent that visual testing (VT) is a very widely used form of nondestructive testing.