Lesson 12 Shock, Vibration, and Compression 第12课冲击、振动和受压
Lesson 12 Shock，Vibration，and Compression 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 mpacts occurring when vehicles hit potholes, curbs, or railroad tracks
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 mpacts occurring when a package is rolled or tipped over Shock due to rail shunting Shock Resulting from Drops can be treated as manual drops o typical manual handling patterns (Figure 12. 1)the basic predictability of package handling
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 12.1)(the basic predictability of package handling)
Shock 100 90 80 70 60 50 10 10 20 30 40 60 70 Drop height(inches) Figure 12. 1 Cumulative percentage and drop height in next day air parcel delivery for United States Postal Service
Shock Figure 12.1 Cumulative percentage and drop height in next day air parcel delivery for United States Postal Service
Shock generalized drop probability curves (Figure 12.2 illustrating another predictable feature of manual handling: the lighter the package, the higher the probable drop height
Shock ⚫ generalized drop probability curves (Figure 12.2) illustrating another predictable feature of manual handling: the lighter the package, the higher the probable drop height
Shock 0. 019 Probability O1% Probabilit Proba g20 1.0%o Probability 10 10P Probability 0102030405060 100 120 140160 Package weight(pounds) Figure 12.2 Generalized drop-height probability curves. The curves flatten out at the point where mechanical handling predominates
Shock Figure 12.2 Generalized drop-height probability curves. The curves flatten out at the point where mechanical handling predominates
Shock o Purposes: 1. probable 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 e 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 ⚫ Purposes: 1.probable 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 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 by lowering the container relative to the floor Cautionary labeling (fragile, this side up, handle with care) has only a minor effect. Cautionary labeling is no substitute for sound packaging practice Address labels tend to orient the drop to a label- up position regardless of other instructions
Shock The larger or bulkier the package, the lower the probable drop height. Handholds reduce the probable drop height by lowering the container relative to the floor. Cautionary labeling (fragile, this side up, handle with care) has only a minor effect. Cautionary labeling is no substitute for sound packaging practice. Address labels tend to orient the drop to a labelup position regardless of other instructions
Shock The usual results of drops and shocks fall into two categories protective or containment qualities are reduced bending, distortion, or, ultimately, breakage Shock During Rail Transport: Railcar coupling: boxcars assembled into trains by moving individual cars, The average shunting speed is 8. 4 kilometres per hour. This is the average speed; some of the impacts are at greater speeds! (Figure 12.3)
Shock ⚫ The usual results of drops and shocks fall into two categories: protective or containment qualities are reduced bending, distortion, or, ultimately, breakage Shock During Rail Transport: Railcar coupling: boxcars assembled into trains by moving individual cars; The average shunting speed is 8.4 kilometres per hour. This is the average speed; some of the impacts are at greater speeds! (Figure 12.3)