Learning Forum

[nz408767]

Hello everybody,

I did some laboratory tests with axially loaded screws, drawn into Wood. The aim of these laboratory tests was to find out the maximal force before the wood fails under tension. Now I want to re-model the results with Ansys Mechanical, to reflect the stress distribution in Wood and Screw.

To model the wood (Spruce-glued laminated timber GL24h) I chose an orthotropic elasticity with orthotropic stress limits as it is shown in the graphic below:

[Ashish Khemka]

Please see if the following link helps:

Stress Analysis of Bolted Joints Part I. Numerical Dimensioning Method (scirp.org)

Regards Ashish Khemka

[nz408767]

Dear akhemka Thanks for your answer. The linked article is about pre-tightened bolted joints in steel constructions and includes just linear elastic material. The problem with the stress distribution along the surface of the screw in contact with the orthotropic material is not related to the article.
The load-bearing behavior of countered steel connections with bolts and nuts is different from the load bearing behavior of axially and laterally loaded screws in timber connections. Differences for example are the pre- tightening of the connection and the compliant failure due to the orthotropic material (a cracked zone modeling might be necessary). The parameters had been choosen so that the timber is significant for the failure of the connection.

[peteroznewman]

Please read the following discussion: /forum/discussion/470/simple-method-for-simulating-local-deformation-near-fastener-threads