- Stress analysis
Stress analysis is an
engineeringdiscipline that determines the stress in materials and structures subjected to static or dynamic forces or loads (see staticsand dynamics) (alternately, in linear elastic systems, strain can be used in place of stress).
The aim of the analysis is usually to determine whether the element or collection of elements, usually referred to as a structure, can safely withstand the specified forces. This is achieved when the determined stress from the applied force(s) is less than the "ultimate
tensile strength", "ultimate compressive strength" or fatigue strength the material is known to be able to withstand, though ordinarily a factor of Safetyis applied in design.
The factor of safety is a design requirement for the structure based on the uncertainty in loads, material strength (yield and ultimate), and consequences of failure. Often a separate factor of safety is applied to the yield strength and to the ultimate strength. The factor of safety on yield strength is to prevent detrimental deformations and the factor of safety on ultimate strength is to prevent collapse. The factor of safety is used to calculate a maximum allowable stress.
Factor of Safety = Ultimate Tensile Strength/Maximum allowable stress
When performing stress analysis, a Design Factor is calculated to compare with the required factor of safety. The factor of safety is a design requirement given to the stress analyst. The Analyst calculates the design factor.
Margin of safetyis another way to express the design factor.
Design Factor = Ultimate Tensile Strength / Maximum Calculated Tensile Stress
A key part of analysis involves determining the type of loads acting on a structure, including
tension, compression, shear, torsion, bending, or combinations of such loads.
Sometimes the term stress analysis is applied to mathematical or computational methods applied to structures that do not yet exist, such as a proposed
aerodynamicstructure, or to large structures such as a building, a machine, a reactor vessel or a piping system.
A stress analysis can also be made by actually applying the force(s) to an existing element or structure and then determining the resulting stress using
sensors, but in this case the process would more properly be known as testing (destructive or non-destructive). In this case special equipment, such as a wind tunnel, or various hydraulic mechanisms, or simply weights are used to apply the static or dynamic loading.
When forces are applied, or expected to be applied, repeatedly, nearly all materials will rupture or fail at a lower stress than they would otherwise. The analysis to determine stresses under these cyclic loading conditions is termed fatigue analysis and is most often applied to aerodynamic structural systems.
The evaluation of loads and stresses within structures is directed to finding the load transfer path. Loads will be transferred by physical contact between the various component parts and within structures. The load transfer may be identified visually, or by simple logic for simple structures. For more complex structures, more complex methods such as theoretical
solid mechanicsor by numerical methods may be required. Numerical methods include Direct Stiffness Methodwhich is also referred to as the Finite element method.
The object is to determine the critical stresses in each part, and compare them to the strength of the material (see Strength of materials).
For parts that have broken in service, a
Forensic engineeringor failure analysisis performed to identify weakness, where broken parts are analysed for the cause or causes of failure. The method seeks to identify the weakest component in the load path. If this is the part which actually failed, then it may corroborate independent evidence of the failure. If not, then another explanation has to be sought, such as a defective part with a lower tensile strengththan it should for example.
List of Stress Analysis Software
ROHR2 (analysis software)
* Worst Case Circuit Analysis
Wikimedia Foundation. 2010.
Look at other dictionaries:
stress analysis — Usually called stress testing but also known as stress analysis or stress scenario analysis. Modeling a series of unusual, hypothetical events or scenarios. Stress tests may model the impact of extreme market conditions, or they may model the… … Financial and business terms
Voice stress analysis — (VSA) technology is said to record psychophysiological stress responses that are present in human voice, when a person suffers psychological stress in response to a stimulus (question) and where the consequences may be dire for the subject being… … Wikipedia
Stress (physics) — Stress is a measure of the average amount of force exerted per unit area. It is a measure of the intensity of the total internal forces acting within a body across imaginary internal surfaces, as a reaction to external applied forces and body… … Wikipedia
Stress intensity factor — Stress Intensity Factor, K, is used in fracture mechanics to more accurately predict the stress state ( stress intensity ) near the tip of a crack caused by a remote load or residual stresses.It is a theoretical construct applicable to a… … Wikipedia
Stress (mechanics) — Continuum mechanics … Wikipedia
stress scenario — Usually called stress testing but also known as stress analysis or stress scenario analysis. Modeling a series of unusual, hypothetical events or scenarios. Stress tests may model the impact of extreme market conditions, or they may model the… … Financial and business terms
stress testing — Usually called stress testing but also known as stress analysis or stress scenario analysis. Modeling a series of unusual, hypothetical events or scenarios. Stress tests may model the impact of extreme market conditions, or they may model the… … Financial and business terms
Stress hyperglycemia — (also called stress diabetes or diabetes of injury) is a medical term referring to transient elevation of the blood glucose due to the stress of illness. It usually resolves spontaneously, but must be distinguished from various forms of diabetes… … Wikipedia
Stress corrosion cracking — (SCC) is the unexpected sudden failure of normally ductile metals or tough thermoplastics subjected to a tensile stress in a corrosive environment, especially at elevated temperature (in the case of metals). SCC is highly chemically specific in… … Wikipedia
Stress majorization — is an optimization strategy used in multidimensional scaling (MDS) where, for a set of n , m dimensional data items, a configuration X of n points in r( … Wikipedia