Abstract Modification of wood improves certain properties of natural wood and presents competitive alternatives to synthetic materials that may have larger environmental impacts. One aspect of modified wood that is currently not fully understood is the dynamic performance and how it is affected by the modification process. In this study, low-molecular weight phenol formaldehyde (PF) resin was applied to Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) wood. The effect of this modification was evaluated using a three-point bending test undergoing cyclic loading. Compared to reference samples, modified wood showed higher static performance but revealed a reduction in cyclic fatigue strength (9% for pine and 14% for beech). Cyclic fatigue strength of unmodified wood was found to be 67% of the static modulus of rupture for both species. With PF resin modification, the fatigue strength dropped to 58% for pine and 53% for beech. While fatigue strength decreased, there was no reduction in cyclic modulus or change in the creep rate within the stationary creep phase. It is important to consider the reduction in fatigue strength when using PF modified wood for any construction purposes with expected cyclic loading conditions.

中文翻译：

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低分子量酚醛树脂改性榉木和松木的疲劳性能

摘要 木材的改性改善了天然木材的某些特性，并为可能对环境产生更大影响的合成材料提供了具有竞争力的替代品。目前尚未完全了解改性木材的一个方面是动态性能以及它如何受改性过程的影响。在本研究中，将低分子量酚醛 (PF) 树脂应用于苏格兰松 (Pinus sylvestris L.) 和欧洲山毛榉 (Fagus sylvatica L.) 木材。使用三点弯曲试验进行循环加载来评估这种修改的效果。与参考样品相比，改性木材显示出更高的静态性能，但显示循环疲劳强度降低（松木为 9%，山毛榉木为 14%）。发现未改性木材的循环疲劳强度是两种木材静态断裂模量的 67%。通过PF树脂改性，松木的疲劳强度下降到58%，山毛榉的疲劳强度下降到53%。虽然疲劳强度降低，但循环模量没有降低或在静止蠕变阶段蠕变速率没有变化。当将 PF 改性木材用于任何具有预期循环载荷条件的建筑目的时，考虑疲劳强度的降低是很重要的。