Shock 815 目90 10 2345 7891011121314 Impact speed(mph) Figure 12. 3 Distribution of rail coupling speeds
Shock Figure 12.3 Distribution of rail coupling speeds
Shock o Shipper experience suggests that damage is greater for rail than for truck shipment The high damage rates attributed to rail are probably due not so much to the actual shock forces as to load shifts and the effects of dynamic compression o Good loading and bracing and securing(dunnage practices can substantially reduce rail damage e TOFC shipping may be gentler than regular boxcar shipping
Shock ⚫ Shipper experience suggests that damage is greater for rail than for truck shipment. ⚫ The high damage rates attributed to rail are probably due not so much to the actual shock forces as to load shifts and the effects of dynamic compression. ⚫ Good loading and bracing and securing (dunnage) practices can substantially reduce rail damage. ⚫ TOFC shipping may be gentler than regular boxcar shipping
Shock Other Shock Conditions occurs during the bumps and bangs, typical of mechanical handling and transport; not as great as that experienced during manual handling and free-fal drops,i.e. a package that will withstand manual handling shocks will survive mechanical handling o Repetitive shock": the low-frequency bouncing or rattling; not likely to cause typical shock damage however, abrasion can occur, and if the product is in resonance with the input frequency, various forms of mechanical damage may develop(vibration-induced damage)
Shock Other Shock Conditions: ⚫ occurs during the bumps and bangs, typical of mechanical handling and transport; not as great as that experienced during manual handling and free-fall drops; i.e., a package that will withstand manual handling shocks will survive mechanical handling. ⚫ “Repetitive shock”: the low-frequency bouncing or rattling; not likely to cause typical shock damage; however, abrasion can occur, and if the product is in resonance with the input frequency, various forms of mechanical damage may develop (vibration-induced damage)
Shock Quantifying Shock Fragility protection against shock damage provided and a knowledge of how fragile or sturdy the product is o cushioning system based on the product's quantified ability to withstand shock quantifying shock fragility in terms of drop height is useful only if no additional protection is anticipated. for products that may experience drops in their use environment: cell telephones, consumer electronics and laptop computers
Shock Quantifying Shock Fragility: ⚫ protection against shock damage provided and a knowledge of how “fragile” or “sturdy” the product is. ⚫ cushioning system based on the product's quantified ability to withstand shock. ⚫ quantifying shock fragility in terms of drop height is useful only if no additional protection is anticipated. for products that may experience drops in their use environment: cell telephones, consumer electronics and laptop computers
Shock o Fragility factor: critical acceleration, or G, levels to describe an object's tendency to break when subjected to shock. An object will break if subjected to a force greater than its structure can bear Newtons second law F= ma observed accelerati on accelerati on of gravit o Since mass is constant for a given packaging problem, force is directly proportional to G [Example] for a cup, m=200 gram, h=1m
Shock ⚫ Fragility factor: “critical acceleration”, or “G,” levels to describe an object's tendency to break when subjected to shock. An object will break if subjected to a force greater than its structure can bear. Newton’s second law: F = ma G = ⚫ Since mass is constant for a given packaging problem, force is directly proportional to G. [Example] for a cup, m=200 gram, h=1m accelerati on of gravity observed accelerati on