Metsä- ja puuteknologian perusteet (4 ov)

Forest Products Mechanics (6 Ects / 4ov) 160317

Puutuotteiden mekaniikka

Petri P. Kärenlampi

Lectures 26 h, Exercises 40 h, literature and examinations 94 h

Strain. Stress. Stress-strain relations. Co-ordinate transformations. Time-dependent mechanical behavior. Moisture and temperature effects.

Irrecoverable deformations. Energy dissipation. The fracture energy.

Brittleness. Strain-softening.

Lectures 26 hours:

Monday, Tuesday, Wednesday

4.9. 2006, 8-10, Room B2

Normal Strain

Normal Stress

Stress-Strain Relations

11.9. 8-10, Room B2

Volumetric Strain

Shear Strain

Shear Stress

12.9. 8-10, Room B2

Multiaxial Stress and Strain States

Off-Axis Stress and Strain

Stress and Strain Transformations

13.9. 10-12, Room B2

Time-Dependent Mechanical Behavior

18.9., 8-10, Room B2

Moisture and Temperature Effects

19.9. 8-10, Room B2

Time-Temperature-Moisture-Specific Volume – Equivalency

20.9. 10-12, Room B2

Irrecoverable Deformations

25.9. 8-10, Room B2

Energy Dissipation

26.9. 8-10, Room B2

The Fracture Energy

27.9. 10-12, Room B2

Brittleness and Strain-Softening

2.10. 8-10, Room B2

Wood Products Applications

3.10. 8-10, Room B4

Pulping Applications

4.10. 10-12, Room B2

Paper and Paperboard Applications

Exercises September-October 2006.

Reporting Sessions for Exercises on October 23th (Room B10) and 24th (Room B10), at 8-10.

Course Literature:

Tsai, S. W. and Hahn, H. T., Introduction to composite materials. Technomic Publishing Co., Westport, CT, 1980, pp. 1-113.

Simo, J. C. and Hughes, T. J. R., Computational inelasticity. Interdisciplinary applied mathematics, Springer Verlag 1998, pp. 1-70.

Smith, T. L., Stress-strain-time-temperature relationship for polymers. ASTM Materials Sci. Series 3, STP-325. American Society of Testing and Materials, New York, NY, 1962, pp. 60-89.

Anderson, T. L., Fracture Mechanics: Fundamentals and Applications. CRC Press, Boca Raton, Florida, 2. ed. 1995, pp. 1-99.

Handwritten lecture notes

Final examination October 30, 2006 at 8-10, Room BOR155.

Possibility for eventual renewals November 13, 2006 at 8-10, Room BOR155.

In addition, the Dean has decided that an examination can be taken in the common examinations of January 12, June 1, and August 10, 2007.

Exercises Contents:

There are two types of exercises:

1. Implementation and analysis of mechanical experiments

The approximated time consumption of this exercise is 27 hours, of which 2 hours in implementation of the experiment, and 25 hours for analyzing the results.

Detailed instructions are given below.

Briefly, the exercises contain

Experimental determination of:

Dynamic Small-Strain Stiffness

Stress-Strain Curve

Tangential Stiffness

Irrecoverable Strain

Thermal expansion

Dynamic Large-Strain Stiffness

Energy Dissipation

The effect of the following factors on the characteristics above

will be investigated:

Temperature

Straining Rate

2. Presentation of an application of mechanics in the Forest Products Industry

The approximated time consumption of this exercise is 13 hours, which is budgeted for the study of an application, on the basis of literature, and the preparation of a presentation regarding it. The presentations (each of duration 20...30 minutes, followed by discussion) will be given during the three last sessions of the lecture program.

Any presentation of application is supposed to based in documents identified by the instructor. The title of the presentation is to be designed by the presenter. The following literature is to be used as a basis of presentations. Any participant may choose one of the following groups of references:

3211. Brebner, K. I., Schneider, M. H. and St-Pierre, L. E., Flexural strength of polymer-impregnated eastern white pine. For. Prod. J. 35(2):22-27 (1985).

3210. Brebner, K. I., Schneider, M. H. and Jones, R. T., The influence of moisture content on the flexural strength of styrene-polymerized wood. For. Prod. J. 38(4):55-58 (1988).

3217. Schneider, M. H., Phillips, J. G., Tingley, D. A. and Brebner, K. I., Mechanical properties of polymer-impregnated sugar maple. For. Prod. J. 40(1):37-41 (1990).

3215. Schneider, M. H., Brebner, K. I. and Hartley, I. D., Swelling of a cell lumen filled and cell-wall bulked wood polymer composite in water. Wood Fiber Sci. 23(2):165-172 (1991).

3845. English, B. W. and Falk, R. H., Factors that affect the application of woodfiber-plastic composites. In Proceedings: "Woodfiber-plastic composites: virgin and recycled wood fiber and polymers for composites", May 1-3, 1995, Madison, Wisc., pp. 189-194. Forest Products Society, Madison, Wisc.

3852. Kortschot, M. T., Engineering design and materials seclection: principles and applications for woodfiber-polymer composites. Fourth International Conference on Woodfiber-Plastic Composites, May 12-14, 1997, Madison, Wisc., pp. 113-116. Forest Products Society, Madison, Wisc.

3835. Simonsen, J., The mechanical properties of woodfiber-plastic composites: theoretical vs. experimental. In Proceedings: "Woodfiber-plastic composites: virgin and recycled wood fiber and polymers for composites", May 1-3, 1995, Madison, Wisc., pp. 47-55. Forest Products Society, Madison, Wisc.

3854. Maiti, S. N., Wood flour-polypropylene composites: structure-property relationships. Fourth International Conference on Woodfiber-Plastic Composites, May 12-14, 1997, Madison, Wisc., p. 133. Forest Products Society, Madison, Wisc.

3866. Selke, S. E. and Childress, J., Wood fiber/high-density polyethylene composites: ability of additives to enhance mechanical properties. In:"Wood-Fiber/Polymer Composites: Fundamental Concepts, Processes, and Material Options", Ed. M. P. Wolcott. Forest Products Society, Madison, Wisc. 1993, pp. 109-111.

4495. Stamm, A. J., Burr, H. K. and Kline, A. A., Staybwood – a heat stabilized wood. Ind. Eng. Chem. 38(6):630-634 (1946).

4498. Stamm, A. J.,Thermal degradation of wood and cellulose. Ind. Eng. Chem. 48:413-417 (1956).

4499. Stamm, A. J. and Baechler, R. H., Decay resistance and dimensional stability of five modified woods. Forest Prod. J. 10:22-26 (1960).

4496. Hillis, W. E., High temperature and chemical effects on wood stability. Wood Sci. Tech.18:281-293 (1984).

4487. Santos, J. A., Mechanical behaviour of Eucalyptus wood modified by heat. Wood Sci. Tech. 34(1):39-43 (2000).

4315. Kamdem, D. P., Pizzi, A. and Jermannaud, A., Durability of heat-treated wood. Holz als Roh- un Werkstoff 60(1):1-6 (2002).

4489. Thermowood. Finnish thermowood association.

http://www.thermowood.fi/pdf/thermowood_english.pdf

4490. Inoue, M., Norimoto, M., Tanahashi, M. and Rowell, R. M., Steam of heat fixation of compressed wood. Wood Fiber Sci. 25:224-235 (1993).

4491. Ito, Y., Tanahashi, M., Shigematsu, M., Shinoda, Y. and C. Ohta, C., Compressive-Molding of wood by high-pressure steam-treatment: Part 1. Development of compressively molded squares from thinnings. Holzforschung 52:211-216 (1998).

4492. Ito, Y., Tanahashi, M., Shigematsu, M. and Shinoda, Y., Compressive-molding of wood by high-pressure steam-treatment: Part 2. Mechanism of permanent fixation. Holzforschung 52:217-221 (1998).

4103. Tanahashi, M., Kyomori, K., Shigematsu, M. and Onwona-Agyeman, S., Development of compressive molding process of wood by high-pressure steam and mechanism of permanent fixation for transformed shape. Fist International Conference of the European Society of Wood Mechanics, April 19-21, 2001, Lausanne, Swizerland, pp. 523-531.

4104. Heger, F., Girardet, F., Moeckli, P. and Navi, P., Thermo-hydro-mechanical demsification and influence of post-treatment on set-recovery. Fist International Conference of the European Society of Wood Mechanics, April 19-21, 2001, Lausanne, Swizerland, pp. 493-502.

4466. Wallström, L., Lindberg, K. A. H. and Johansson, I., Wood surface stabilization. Holz als Roh- und Werkstoff 53:87-92 (1995).

4467. Wallström, L., and Lindberg, K. A. H., Wood surface stabilization with polyethylene glycol, PEG. Wood Sci. Tech. 29:109-119 (1995).

4465. Wallström, L., and Lindberg, K. A. H., Measurement of cell wall penetration in wood of water-based chemicals using SEM/EDS and STEM/I. Wood Sci. Tech. 33(2):111-122 (1999).

4386. Kifetew, G.,Thuvander, F., Berglund, L. A. and Lindberg, H., The effect of drying on wood fracture surfaces from specimens tested in wet condition, Wood Sci. Tech. 32(2):83-94 (1998).

4034. Thuvander, F., Wallström, L., Berglund, L. A. and Lindberg, K. A. H., Effects of an impregnation procedure for prevention of wood cell wall damage due to drying. Wood Sci. Tech. 34(6):473-480 (2001).

3512. Björkqvist, T., Menetelmä ja laite puun mekaaniseksi kuiduttamiseksi. Förfarande och anordning för mekanisk defibrering av trä. Finnish Patent 98148 (1995). WO9638624: Method and apparatus for mechanical defibration of wood, published 1996-12-05.

4230. Björkqvist, T. and Lucander, M., Grinding surface with an energy-efficient profile. 2001 International Mechanical Pulping Conference, Helsinki, Finland, June 4-8, 2001, pp. 373-380.
I/

55. Kärenlampi, P. P., Tynjälä, P. and Ström, P.: Molecular fatigue in cell walls. 2002 Paper Physics Seminar, Finger Lakes, NY, Sept. 8-13, pp. 240-243.

40. Kärenlampi, P. P., Tynjälä, P. and Ström, P.: Molecular reorganization in wood. Mechanics of Materials 35(?):??-?? (2003)

2623. Östlund, S., Niskanen, K. and Kärenlampi, P., On the prediction of the strength of paper structures with a flaw. J. Pulp Paper Sci. 25(10):353-360 (1999).

3579. Östlund, S. and Kärenlampi, P., Structural geometry effect on the size-scaling of strength. Int. J. Fract. 109(2):141-151 (2001).

2661. Tryding, J. and Gustafsson, P. J., Characterisation of tensile fracture properties of paper. Tappi 83(2):84-89 (2000).

3622. Tryding, J. and Gustafsson, P. J., Analysis of notched newsprint sheet in mode I fracture. J. Pulp Paper Sci. 27(3):103-109 (2001).

3342. Uesaka, T. and Ferahi, M., Principal factors controlling press room breaks. 1999 Paper Physics Conference, San Diego, CA, Sept. 26-30, 1999, pp. 229-245.

4486. Uesaka, T., Ferahi, M., Hristopulos, D., Deng, N. and Moss, C., Factors controlling press room runnability of paper . 12th Fundamental Research Symposium, Oxford, England, Sept. 2001 (Ed. C.F. Baker), Vol. 2, Ch. 8pp. 1423-1440.

4452. Hristopoulos, D. T. and Uesaka, T., Model of machine-direction web dynamics and impact on web brake rates. PPP2002, Progress in Paper Physics Seminar, Finger Lakes / Syracuse, NY, Sept. 8-13, 2002, pp. 206-209.

3362. Wahlström, T., Adolfsson, K., Östlund, S. and Fellers, C., Numerical modeling of the cross direction shrinkage profile in a dryer section. A first approach. 1999 Paper Physics Conference, San Diego, CA, Sept. 26-30, 1999, p. 517-531.

2976. Glynn, P., Jones, H. W. H. and Gallay, W., The fundamentals of curl in paper. Pulp Paper Can. 60(19):T316-323 (1959).

2973. Gray, D. G., Chirality and curl in paper sheets. J. Pulp Paper Sci. 15(3):J105-109 (1989).

4458. Östlund, M., Östlund, Ö., Carlsson, L. A. and Fellers, C., Experimental determination of residual stresses in paperboard. PPP2002, Progress in Paper Physics Seminar, Finger Lakes / Syracuse, NY, Sept. 8-13, 2002, pp. 180-183..

4443. Persson, M. and Wahlström, T., The development of moisture gradients using different stategies and their influence on process-induced curl. PPP2002, Progress in Paper Physics Seminar, Finger Lakes / Syracuse, NY, Sept. 8-13, 2002, pp. 131-135.

Forest Products Mechanics (4ov) 160317

Please enter no later than September 4, 2006.

Please print.

Name date

Instructions for Experimental Exercise:

Experimental determination of:

Dynamic Small-Strain Stiffness

Stress-Strain Curve

Tangential Stiffness

Irrecoverable Strain

Thermal expansion

Dynamic Large-Strain Stiffness

Energy Dissipation

The effect of the following factors on the characteristics above

will be investigated:

Temperature

Straining Rate

Instructions for Experimental Exercise:

Specimen:

Fresh Spruce heartwood specimen 34mm * 34mm * 9mm, soaked in water overnight before experiments, tested in uniaxial strain in the tangential material direction.

Thermal expansion:

Maintain the specimen under a load of 50 N while treating with saturated steam at XXX°C for a period of 30 minutes. Report the uniaxial thermal expansion.

Dynamic Small-Strain Stiffness:

Define the thickness after thermal expansion as the thickness with zero strain. Determine dynamic small-strain stiffness at strain control, at mean compressive strain of 1.5 %, with strain amplitude 0.5%, at two loading frequencies:

- 1 Hz

- 10 Hz.

Detailed instructions:

Determine minimum strain and maximum strain as arrays moving over three consecutive loading cycles. Determine minimum stress and maximum stress as arrays moving over three consecutive loading cycles. Determine dynamic stiffness as a the ratio of stress amplitude to strain amplitude. Plot dynamic stiffness as a function of the number of loading cycles.

Stress-Strain Curve:

Determine stress-strain curve by compressing to 80% logarithmic compressive strain at rate YY%/s. Recover the applied strain to 10% compressive strain at rate YY%/s. Recover the rest of the applied strain under load control to 50 N. Plot stress as a function of strain.

Irrecoverable Strain after Transient Experiment:

Determine irrecoverable strain by finding the strain which no longer changes under a load of 50 N.

Tangential Stiffness:

Filter the stress and strain data by taking moving averages over 0.25% strain intervals. Determine tangential stiffness as the change of stress over the change of strain over 0.5% strain intervals, using the filtered data. Plot the tangential stiffness data as a function of the strain level.

Dynamic Large-Strain experiment:

Apply a cyclical stress of target set point 1.5 MPa and amplitude 0.5 MPa at YY Hz frequency, the experiment consisting of 100 cycles.

Irrecoverable Strain after Dynamic Experiment:

Determine irrecoverable strain by finding the strain which no longer changes under a load of 50 N.

Dynamic Large-Strain Stiffness:

Energy Dissipation:

Determine work as the integral of force over displacement. (It is important to average the force properly over any incremental displacement.) Determine accumulated applied work as the sum of positive work inputs. Determine accumulated dissipated work as the sum of all mechanical work inputs. Determine mean applied work per loading cycle over three consecutive loading cycles. Determine mean dissipated energy per loading cycle over three consecutive loading cycles. Determine the dissipated energy in relation to the applied work. Filter the result over the number of observations collected within a loading cycle. Plot the dissipated energy proportion as a function of the number of loading cycles.

Dynamic Small-Strain Stiffness after Dynamic Loading:

Redefine the thickness after strain recovery as thickness with zero strain. Determine dynamic small-strain stiffness at strain control, at mean compressive strain of 1.5 %, with strain amplitude 0.5%, at two loading frequencies:

- 1 Hz

- 10 Hz.

Detailed instructions:

Reporting:

Print out the results in terms of graphics mentioned above, as well as and strain values describing thermal expansion and irrecoverable strain. Have the results accepted by the Assistant supervising the exercise. Prepare an overhead presentation – no written report needs to be compiled. Go home and have a cup of hot chocolate.