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A mechanical or physical shock is a sudden acceleration caused, for example, by impact, drop, kick, earthquake, or explosion. Shock is a transient physical excitation. Shock describes matter subject to extreme rates of force wtr to time. Shock is a vector that has units of an acceleration (rate of change of velocity). The unit ''g'' (or g) represents multiples of the acceleration of gravity and is conventionally used. A shock pulse can be characterised by its peak acceleration, the duration, and the shape of the shock pulse (half sine, triangular, trapezoidal, etc.). The Shock response spectrum is a method for further evaluating a mechanical shock. ==Shock measurement== Shock measurement is of interest in several fields such as *Propagation of heel shock through a runner’s body *Measure the magnitude of a shock need to cause damage to an item: ‘’’fragility’’’.〔ASTM D3332-99(2010) Standard Test Methods for Mechanical-Shock Fragility of Products, Using Shock Machines〕 *Measure shock attenuation through athletic flooring 〔ASTM F1543-96(2007) Standard Specification for Shock Attenuation Properties of Fencing Surfaces〕 *Measuring the effectiveness of a shock absorber *Measuring the shock absorbing ability of package cushioning〔ASTM D1596-14 Standard Test Method for Dynamic Shock Cushioning Characteristics of Packaging Material〕 *Measure the ability of an athletic helmet to protect people〔ASTM F429-10 Standard Test Method for Shock-Attenuation Characteristics of Protective Headgear for Football〕 *Measure the effectiveness of shock mounts *Determining the ability of structures to resist seismic shock: earthquakes, etc.〔ASTM STP209 Design and Tests of Building Structures: Symposiums on Seismic and Shock Loading Glued Laminated and Other Constructions.〕 *Determining whether personal protective fabric attenuates or amplifies shocks *Verifying that a Naval ship and its equipment can survive explosive shocks 〔"MIL-S-901D (NAVY), MILITARY SPECIFICATION: SHOCK TESTS. H.I. (HIGH-IMPACT) SHIPBOARD MACHINERY, EQUIPMENT, AND SYSTEMS, REQUIREMENTS FOR"〕 Shocks are usually measured by accelerometers but other transducers and high speed imaging are also used. A wide variety of laboratory instrumentation is available; stand-alone shock data loggers are also used. Field shocks are highly variable and often have very uneven shapes. Even laboratory controlled shocks often have uneven shapes and include short duration spikes; Noise can be reduced by appropriate digital or analog filtering.〔ASTM D6537-00(2014) Standard Practice for Instrumented Package Shock Testing For Determination of Package Performance〕 Governing test methods and specifications provide detail about the conduct of shock tests. Proper placement of measuring instruments is critical. Fragile items and packaged goods respond with variation to uniform laboratory shocks;〔ASTM Research Report D10-1004, ASTM International〕 Replicate testing is often called for. For example MIL-STD-810G Method 516.6 indicates: ‘’at least three times in both directions along each of three orthogonal axes”. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Shock (mechanics)」の詳細全文を読む スポンサード リンク
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