Swept Sine Humidity Schedule for Testing Cycle Period Effects on Creep

Authors

  • Thomas J. Urbanik
  • Sung K. Lee

Keywords:

Corrugated fiberboard, stacking life compression strength, cyclic humidity, testing

Abstract

The stacking life of corrugated containers under load decreases as relative humidity (RH) increases and when RH cycles, compared with when RH remains stable. Conventional RH test schedules that rely on fixed cycle periods do not adequately reflect the significance of moisture diffusion and hygroexpansion rate phenomena on the creep of corrugated containers and general wood fiber products. With cycle periods shorter than a critical period, materials are relatively unaffected by cyclic changes in RH. Longer periods amplify material hygroexpansion and accelerate creep. In this study, we propose a swept sine RH schedule in which the cycle frequency varies logarithmically with time and set forth equations for generating a numerical control signal. Data from creep tests of corrugated fiberboard reveal the frequency dependence of the amplitude and phase relationships between cyclic hygroexpansion and cyclic RH. A swept sine RH schedule yielded the continuous form of the response characteristics varying with cycle period that could not be acquired with multiple constant period schedules. The critical cycle period and the hygroexpansion response to moisture as a function of cycle period are proposed as criteria for discriminating among hygroexpansion-creep models.

References

ASTM. 1990. Standard test method for determining compression resistance of shipping containers, components, and unit loads. ASTM D642. American Society for Testing and Materials, Philadelphia, PA.nBeckwith, T. G., and N. L. Buck. 1969. Mechanical measurements. Addison-Wesley Pub. Co. Inc., Reading, MA.nByrd, V. L. 1984. Edgewise compression creep of fiberboard components in a cyclic-relative-humidity environment. Tappi 67(7):86-90.nByrd, V. L., and J. W. Koning, Jr. 1978. Edgewise compression creep in cyclic relative humidity environments. Tappi 61(6):35-37.nFridley, H. J., R. C. Tang, and L. A. Soltis. 1990. Moisture effects on load-duration behavior of lumber. Part II. Effect of cyclic relative humidity. Wood Fiber Sci. 24(1):89-98.nFridley, H. J., R. C. Tang, and L. A. Soltis. 1992. Creep behavior model for structural lumber. J. Struct. Eng. 118(8):2261-2277.nGressel, V. P. 1986. A proposal for consistent experimental principles for conducting and evaluating creep tests. Holz Roh-Werkst. 44(4):133-138.nGunderson, D. E., and W. E. Tobey. 1990. Tensile creep of paperboard—Effect of humidity change rates. Pages 213-226 in Proceedings, Materials Interactions Relevant to the Pulp, Paper, and Wood Industries. Materials Research Society, Pittsburgh, PA.nLaufenberg, T. L. 1991. Characterization of paper-board, combined board, and container performance in the service moisture environment. Pages 300-302 in Proceedings, TAPPI, International Paper Physics Conference, Kona, HI.nLeake, C., and R. Wojcik. 1992. Humidity cycling rates: How they affect container life spans. Pages 134-144 in Proceedings, Cyclic Humidity Effects on Paperboard Packaging. Forest Products Laboratory, Madison, WI.nMcNatt, J. D. 1993. Moisture—A critical element in duration-of-load/creep research. Proceedings, Oriented Structural Board: Duration of Load Performance. Structural Board Association Workshop, February 16-18. Toronto, Ontario, Canada.nUrbanik, T. J. 1994. Hygroexpansion-creep model for corrugated fiberboard. Proposed for Wood and Fiber Science.n

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Published

2007-06-25

Issue

Number 1 / January 1995

Section

Research Contributions

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