environmental test[in¦vī·ərn¦mənt·əl ′test]
The evaluation of a physical system (engineering product) in conditions which simulate one or more of the environments that may harm the system or adversely affect its performance. In addition to the evaluation of a finished product, environmental testing can play an important role throughout a product's design/development cycle to ensure that the materials and manufacturing processes employed can meet the stresses imposed by the environment in which the product is likely to operate. By not waiting until a finished product is evaluated, manufacturers can use environmental testing to eliminate costly redesigns late in the design/development cycle.
Because it is necessary to precisely control the environmental factors which define the test (for example, temperature, vibration level, or altitude), environmental testing is typically conducted in specially designed facilities, or environmental chambers. Some environmental chambers can generate extremely high and low temperatures and humidity levels. Others can simulate corrosive environments such as salt sprays. Products and equipment intended for military use are often subjected to the harshest and most variable of environmental conditions. The military has pioneered the creation of well-documented standards and specifications for the evaluation and testing of any products or equipment which it will purchase.
Civilian organizations, such as the Society of Automotive Engineers, publish standards for automotive and aerospace equipment. In addition, nearly 100 countries have adopted the International Organization for Standardization (ISO) 9000 series of standards for quality management and quality assurance. These standards are implemented by thousands of manufacturing and service organizations, both public and private. Of the ISO 9000 family standards, ISO 9003 covers quality assurance obligations of the manufacturer in the areas of final inspection and testing. Among the guidelines provided by ISO 9003 are those dedicated to (1) developing procedures to inspect, test, and verify that final products meet all specified requirements before they are sold; (2) developing procedures to control and calibrate the testing equipment; (3) ensuring that every product is identified as having passed or failed the required tests. ISO 9003 will have a significant impact upon the standardization of environmental testing in both civilian and military endeavors.
An incomplete but representative list of environmental tests requiring dedicated test chambers includes tests for altitude, dust, explosiveness, flammability, fungus, humidity, icing, acoustic vibration, overpressure, rain, salt fog, sand, temperature, and wind. Tests typically not requiring chambers but still utilizing dedicated mechanical testing equipment include acceleration, fatigue cycling, transportation simulation, shock, and vibration.