<unk>  (sometimes called torture<unk>  is a form of deliberately intense or thorough<unk>  used to determine the stability of a given system, critical infrastructure or entity. It involves<unk>  beyond normal operational capacity, often to a breaking point, in order to observe the results. Reasons can include: * to determine breaking points or safe usage limits * to confirm mathematical model is accurate enough in predicting breaking points or safe usage limits * to confirm intended specifications are being met * to determine modes of failure (how exactly a system fails) * to test stable operation of a part or system outside standard usage Reliability engineers often test items under expected<unk>  or even under accelerated<unk>  in order to determine the operating life of the item or to determine modes of failure. The term<unk> " may have a more specific meaning in certain industries, such as material sciences, and therefore<unk>  may sometimes have a technical meaning – one example is in fatigue<unk>  for materials.
Stress testing
Ballistocardiography
Magnetocardiography
Cardiac stress test
Myocardial perfusion imaging
Vectorcardiography
Electrocardiography
Cardiotocography