MAINTAINABILITY DESIGN TECHNIQUES METRIC - AcqNotes.com

Downloaded from http://www.everyspec.com on 2011-10-29T14:56:01.DOD-HDBK-791(AM)TABLE 10-11 (cont’d)WindRainEnvironmentalFactorWater immersionInsects and bacteriaFungiTemperature shockHigh-speed particles(nuclear irradiation)OzoneExplosive decompressionDissociated gasesAccelerationForce applicationPrincipal EffectsDeposition of materialsHeat loss (low velocity)Heat gain (high velocity)Physical stressWater absorption and immersionErosionCorrosionCorrosion of metalsChemical deteriorationHigh pressure(13 psi at 30-ft depth)Penetration into equipmentNibbling by termitesGrowth of molds, hyphaeMechanical stressHeatingTransmutation and ionizationChemical reactions:Crazing, crackingEmbrittlementGranulationReduced dielectric strength of airSevere mechanical stressChemical reactions:ContaminationReduced dielectric strengthMechanical stressTypical Failures InducedStructural collapseInterference with functionLoss of mechanical strengthMechanical interference and cloggingAbrasion acceleratedAccelerated low-temperature effectsAccelerated high-temperature effectsStructural collapseIncrease in weightStructural weakeningAccelerates coolingElectrical failureRemoves protective coatingsStructural weakeningSurface deterioriationEnhances chemical reactionsStructural weakness, seizure of parts,contamination of productsDissolving out and changing of materialsMechanical damageBlockage of small parts, meters, etc.Damage to plastic cables or other organicinsulating materials, causing shortsDamage to optical equipment; leakage pathsin high impedance circuits; blockage ofsmall parts, meters, etc.; breakdown ofmechanical strength of all organic materialsStructural collapse or weakeningSeal damageThermal agingOxidationAlteration of chemical, physical, andelectrical propertiesProduction of gases and secondary particlesRapid oxidationAlteration of chemical, physical, andelectrical propertiesLoss of mechanical strengthInterference with functionInsulation breakdown and arc-overRupture and crackingStructural collapseAlteration of physical and electricalpropertiesInsulation breakdown and arc-overStructural collapse(cont’d on next page)10-20