Simulation of cracks in wood using a coupled material model for interface elements

Holzforschung ◽  
2007 ◽  
Vol 61 (4) ◽  
pp. 382-389 ◽  
Author(s):  
Jörg Schmidt ◽  
Michael Kaliske
Keyword(s):  
Stress Component ◽  
Damage Model ◽  
Three Dimensional ◽  
Path Following ◽  
Material Model ◽  
Timber Structures ◽  
Wood Fibers ◽  
Interface Elements ◽  
Material Formulation

Abstract A three-dimensional anisotropic material model is presented that is applicable in combination with interface elements for simulation of the behavior of timber structures loaded in shear and tension perpendicular to the wood fibers. The material model can predict the stresses derived from the three-dimensional state of deformation. Determination of the algorithmic material tangent is shown. Computation of a stress component results from deformation in all directions. Furthermore, a damage model is implemented to simulate cyclic loading that yields a realistic unloading function for a cracked structure. In this case, a continuous-differentiable material formulation guarantees a robust path-following algorithm. A basic example is used to demonstrate the capability of the model to simulate the behavior of timber structures realistically and underlines the need for further research.

scholarly journals Using DEFORM Software for Determination of Parameters for Two Fracture Criteria on DIN 34CrNiMo6

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 445
Author(s):  
Ivana Poláková ◽  
Michal Zemko ◽  
Martin Rund ◽  
Ján Džugan
Keyword(s):  
Fracture Criterion ◽  
Damage Model ◽  
Material Model ◽  
Mechanical Tests ◽  
Fracture Criteria ◽  
Stress States ◽  
Determination Of Parameters ◽  
Accuracy Of Prediction ◽  
Good Agreement

The aim of this study was to calibrate a material model with two fracture criteria that is available in the DEFORM software on DIN 34CrNiMo6. The purpose is to propose a type of simple test that will be sufficient for the determination of damage parameters. The influence of the quantity of mechanical tests on the accuracy of the fracture criterion was explored. This approach was validated using several tests and simulations of damage in a tube and a round bar. These tests are used in engineering applications for their ease of manufacturing and their strong ability to fracture. The prediction of the time and location of the failure was based on the parameters of the relevant damage model. Normalized Cockroft-Latham and Oyane criteria were explored. The validation involved comparing the results of numerical simulation against the test data. The accuracy of prediction of fracture for various stress states using the criteria was evaluated. Both fracture criteria showed good agreement in terms of the fracture locus, but the Oyane criterion proved more suitable for cases covering larger triaxiality ranges.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

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