Discussion: Duration of load effects in lumber. Part I: A fracture mechanics approach. Part II: Experimental data. Part III: Code considerations

1983 ◽  
Vol 10 (2) ◽  
pp. 317-319
Author(s):  
Ricardo O. Foschi
Keyword(s):  
Experimental Data ◽  
Fracture Mechanics ◽  
Load Effects ◽  
Duration Of Load

Duration of load effects in lumber. Part II: Experimental data

1982 ◽  
Vol 9 (3) ◽  
pp. 515-525 ◽  
Author(s):  
Borg Madsen ◽  
Kenneth Johns
Keyword(s):  
Experimental Data ◽  
Fracture Mechanics ◽  
Load Test ◽  
Design Practice ◽  
Coefficient Of Correlation ◽  
Similar Test ◽  
Mechanics Model ◽  
Viscoelastic Fracture ◽  
Load Effects ◽  
Duration Of Load

The viscoelastic fracture mechanics model developed in Part I is calibrated using a 70-day duration of load test on commerical lumber. The model is then verified using another similar test on a different population of boards, and on a unique 6-year test just terminated. All three test programs are described. The model is used to tentatively project results beyond the period of testing. The strength predictions of the model compare well with those obtained experimentally during the tests, the coefficient of correlation being 0.95. Implications for design practice are outlined in Part III of this paper.

Duration of load effects in lumber. Part I: A fracture mechanics approach

1982 ◽  
Vol 9 (3) ◽  
pp. 502-514 ◽  
Author(s):  
Kenneth Johns ◽  
Borg Madsen
Keyword(s):  
Fracture Mechanics ◽  
Stress Ratio ◽  
Failure Time ◽  
Creep Function ◽  
Load Effect ◽  
Mechanics Model ◽  
Current Design ◽  
Load Effects ◽  
Duration Of Load

In Part I of this paper, the deterioration of the strength of lumber with continued application of constant stress, called the duration-of-load effect, is treated using a viscoelastic, limited ductility fracture mechanics model. The model is explained and developed in a general way, then modified for use with commercial lumber. The problems of assigning correct creep function parameters and values of stress ratio for use in calculations involving the model are discussed. The evident weakening of boards surviving a long-term test can be used to project a failure time that is longer than the test period. Numerical results are shown and compared with the Madison curve, the basis for current design codes. Parts II and III of this paper demonstrate experimental verification and discuss design implications.

Duration of load effects in lumber. Part III: Code considerations

1982 ◽  
Vol 9 (3) ◽  
pp. 526-536 ◽  
Author(s):  
Borg Madsen ◽  
Kenneth Johns
Keyword(s):  
Fracture Mechanics ◽  
Structural Design ◽  
Design Codes ◽  
Specific Design ◽  
Damage Models ◽  
Mechanics Model ◽  
Complicated Model ◽  
Load Effects ◽  
Elastic Fracture ◽  
Duration Of Load

The implications for practical structural design with wood of a visco-elastic fracture mechanics model, recently developed and verified experimentally by the authors, are presented. These are compared with those of the presently used Madison concept, and with those of the cumulative damage models. Following discussion of present practice and the consequences of the fracture mechanics model, specific design recommendations are made as to how this more complicated model might be incorporated into design codes.

Duration of Load Effects in LRFD for Wood Construction

1991 ◽  
Vol 117 (2) ◽  
pp. 584-599 ◽  
Author(s):  
Bruce Ellingwood ◽  
David Rosowsky
Keyword(s):  
Wood Construction ◽  
Load Effects ◽  
Duration Of Load

System Wear Life Estimation Under Uncertainty

2018 ◽  
Author(s):  
Mohammad Pourmostafaei ◽  
Mohammad Pourgol-Mohammad ◽  
Mojtaba Yazdani ◽  
Hossein Salimi
Keyword(s):  
Experimental Data ◽  
Sliding Wear ◽  
Normal Load ◽  
Material Loss ◽  
Life Estimation ◽  
Wear Life ◽  
Pin On Disc ◽  
Load Effects ◽  
Sliding Distance ◽  
Degradation Evaluation

In this paper, a new model is proposed for system degradation evaluation under sliding wear failure mechanism. This model estimates the material loss by progression of sliding distance. This model is generated by considering physical and geometrical aspects of system under wear mechanism. Several sets of experimental data are used for validation of the presented model. These experimental data are related to pin-on-disc test of Tungsten Carbide pins. These sets of data include initially conformal and non-conformal contacts. One set of data of pin-on-disc test by ASTM-G99 standard is used for additional validation of the model and for investigation of normal load effects on the parameters of presented model. Finally, uncertainty analysis is done by Monte-Carlo simulation to determine the variations of the predicted wear caused material loss.

scholarly journals Energetic criterion in general elastic-plastic fracture mechanics

1993 ◽  
Vol 15 (1) ◽  
pp. 16-20
Author(s):  
Bui Huu Dan
Keyword(s):  
Experimental Data ◽  
Energy Balance ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Numerical Procedure ◽  
Slip Model ◽  
Elastic Plastic

From the analyzing the equation of energy balance for cracked bodies during the crack growth the energetic criterion is formulated for general elastic-plastic fracture mechanics. The numerical procedure should be realized by using the slip model of polycrystalline plasticity and the experimental data.

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