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MATERIALS 45
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ahead of a crack tip and have been successfully used with Piotrekswat
a modified Paris' law to simulate fatigue damage.
Commercial software packages like ABAQUS and ANSYS
are typically used for these complex simulations, with dedicated

modules for composite materials becoming increasingly
available for wood-based products. These tools allow for the
optimisation of designs to be both lighter and safer against
fatigue failure.

Findings from very unfavourable to very favourable.
We reviewed the current work, research, findings, and results The descriptive states correspond to quantitative values
in the field of wood fatigue. Density and moisture content from 0 to 1, from which we have obtained an evaluation of the
are the most important influencing factors in static strength influence of the individual factors. The quantitative evaluation

testing, and they play an equally important role in fatigue. of the influence is determined from the difference between
Other factors influencing fatigue include fibre orientation, the average values of the individual states of the physical
mean stress, R-ratio, load cycle waveform, frequency, properties or loads.
and temperature. Many of these influencing factors are For example, the overall rating of the influence of density
interdependent, and their effects are shown in Table 1 below is the difference between the average value of the rating at
using a colour scale. low density and at high density. Similarly, the overall influence
rating is also determined for mean stress, which has the
Table 1: Wood fatigue influential factors.
highest value, confirming the appropriateness of the influence
rating method.
Throughout the review, we discussed research by many
authors who used various wood species, engineered wood,
and composites in fatigue tests to determine fatigue strength,
investigate influential factors, and develop prediction models.
We examined the equipment and methods used for
collecting experimental data, as well as the models used to
predict and simulate fatigue life. Finally, we identified areas

The factors are divided into physical properties and loads. where fatigue is the main cause of failure and noted that
Some properties and loadings have two states, for example, wood has good resistance to fatigue.
low density (LD) and high density (HD), or low mean stress The most important findings on the response of wood to
(LMS) and high mean stress (HMS). cyclic loads under various influencing factors are shown in
Combinations of different states of physical properties Table 1 above. Additional findings that determine approaches
and stresses are indicated by abbreviations, such as the for addressing the response of wood to cyclic loads are as
combination of low density and low mean stress (LD-LMS), follows:

where the influence of the combination is indicated by a colour, • The α−N curve is monotonically decreasing up to 109
as shown in the table legend. The evaluation criterion ranges cycles.