DOWEL – A Software to Simulate Dowel-Type Connectors in Wood or Other Materials


The DOWEL program is a finite-element modeler for dowel-type connections (e.g. nails, bolts, lag screws) in wood-wood, wood-steel or any other type of connection material configuration. The underlying model has even been used for pile modeling in soil. It calculates load-displacement curves for monotonic and cyclic loading applictions and plots deformed shapes at predefined displacement steps. Material inputs consist of basic material embedment data. All material data is stored in a database that can be appended by the user.

This software is provided free of charge. A working example has been included with the installer. Please read the terms of the license that is provided with the software before using it.

Please consult the online documentation for further details on the software. For any documentation on the theory or an application example, see my Master’s thesis page.


This software allows you to simulate the structural (load-displacement) behaviour of a single dowel-type fastener. In wood connections, the fastener typically is a nail, bolt, dowel, lag screw or similar. When several pieces of wood are fastened together, the fastener penetrates at least two of them. These are represented by layers in this software. The fastener is represented by several one-dimensional beam elements, whose numbers and lengths can be specified separately for each layer allowing for a refinement of the FE mesh, if desired.

To run a simulation, only basic material data is needed. Since the fastener is assumed to have a bilinear stress-strain behaviour, only two parameters – Young’s modulus and the yield stress – need to be known. These can be derived from tests or literature. The layers have a 6-parametric exponential behaviour expressed by two curves. These parameters can also be derived from tests or taken from the supplied materials database. It should be noted that the layer behaviour also includes effects from the fastener diameter, shape, surface type (friction), so that a reverse-engineered (fitted) approach might lead to a more precise derivation of these parameters.

In essence, DOWEL is a pre- and postprocessor for the DHYST and FEMFIT programs, which are both supplied and installed when you run the installer. It allows for model and displacement history generation, execution of the simulation (DHYST) and fitting (FEMFIT) programs using parameters and evaluation of the calculated results using a text editor and an x-y data plotter. In addition, two newly added routines allow for the computation of an average curve from a set of monotonic x-y type curves and the calculation of the enclosed area under a monotonic or cyclic curve. The latter is useful to estimate the amount of dissipated energy.



Revision History

DOWEL v.1.6 (04.08.2005):

  • GUI: – Updated Win XP interface – Added average curve generator: Creates an average curve from a set of x-y type monotonic curves. This is a good general helper for test data – Added curve area calculator: Calculates the area within a monotonic or cyclic curve. Allows for batch calculation for several curves. This helps in determining the amount of dissipated energy – Added Windows installer with full uninstall support – DHYST or FEMFIT have not been updated – Still the old help file as well
  • Bug Fixes: – Inplace editing dropdown size handling fixed – Grid performance improved

DOWEL v.1.5 (13.09.2002):

  • GUI: – System description dialog to enter fastener geometry and parameters – Materials database, accessed through dialog. User can delete and append materials – Interactive generation of displacement history. No limits on amount of data points – Simple text editor included – x-y data plotter included – Run dialogs for both DHYST (dowel simulation) and FEMFIT (parameter fitting). Although FEMFIT is supported in this release, its performance has not been verified – Installation from ZIP archive
  • Analysis: – Static FE analysis without consideration of dynamic effects – Nonlinear (Newton-Raphson) – P-delta effects included (large displacements)
  • Foundation material (structural members): – Max. 10 layers – Max. 10 different foundation properties – Parametric exponential material behaviour (6 parameters) – Limitation to compressive deformations allows for the creation of gaps – Displacement can be applied to a single layer or multiple layers or at a node point of the fastener – Hole tolerances can be entered for each layer separately
  • Fastener: – Max. 50 elements (2-node isoparametric beam type) – Rectangular, circular or tubular cross-section – Element length can differ from layer to layer – 5 degrees of freedom (DOFs) per node: w, w’, w”, u, u’ – 2,3,4,5,6,7,8 or 9 Gauss integration points along x – 2,3,4,5,6,7,8,9,10,11,12,15,16 or 32 Gauss integration points along y – Shape functions: 5th degree polynomial for w, 3rd degree polynomial for u – Bilinear material behaviour – Fatigue can be simulated using strain softening – Simulation of fastener head behaviour using linear unidirectional spring – Axial force can be specified


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