文档介绍：Lesson 12
Shock,Vibration,pression
第12课冲击、振动和受压
Shock
Defined as an impact, characterized by a sudden and substantial change in velocity.
Shocks in the distribution environment:
Accidental and deliberate drops during manual handling
Drops from chutes, conveyors, and other machinery
Falls from pallet loads
Sudden arrests on conveyors
Impacts occurring when vehicles hit potholes, curbs, or railroad tracks
Shock
Impacts occurring when a package is rolled or tipped over
Shock due to rail shunting
Shock Resulting from Drops:
can be treated as manual drops.
typical manual handling patterns (Figure )(the basic predictability of package handling).
Shock
Figure Cumulative percentage and drop height in next day air parcel delivery for United States Postal Service
Shock
generalized drop probability curves (Figure ) illustrating another predictable feature of manual handling: the lighter the package, the higher the probable drop height.
Shock
Figure Generalized drop-height probability curves. The curves flatten out at the point where mechanical handling predominates.
Shock
Purposes: drop height a given package should be designed to withstand.
2. being the basis of preshipment test procedures and
3. provide information for the development of protective packaging systems.
Fundamental lessons are as follows:
The probability that a package will be dropped from a height greater than 1 meter (40 inches) is minimal.
Shock
Packages receive many drops from low heights, while few receive more than one drop from greater heights.
Skidded, wrapped, or otherwise unitized loads are subject to fewer drops than individual packages.
There is little control over drop orientation with small packages. With larger packages, about half of the drops are on the base.
A heavier package has a lower probable drop height.
Shock
The larger or bulkier the package, the lower the probable drop height.
Handholds reduce the probable drop height