Abstract Damage in oak wood museum objects under indoor climate variations (relative humidity, temperature) is studied using a thermo-hygro-mechanical model. The model incorporates the effects of moisture sorption hysteresis and discrete cracking, and is implemented within a finite element framework using a staggered update procedure. Sorptin experiments were performed in order to calibrate the moisture sorption hysteresis model. The basic features of the coupled formulation are stepwisely demonstrated by solving the response of a basic oak wood specimen under a sequence of thermo-hygro-mechanical loading conditions of increasing complexity. These simulations show that the deformation and fracture generated by thermal variations representative of indoor museum conditions are minor compared to the contributions caused by relative humidity variations. Subsequently, the hygro-mechanical response of an oak wood cabinet door panel is analysed under a drop in relative humidity from 60% to 20%, and the results are compared to those obtained by experiments. The numerical and experimental results are in good agreement, and indicate that at the connection between the cleated end and the vertical boards the restrained hygric shrinkage is maximal, which stimulates local crack development. The susceptibility to fracture only becomes activated after the oak wood has reached a certain age, as the effect of aging induces a decrease of the oak wood tensile strength perpendicular to the grain direction with time. Further, when the initial moisture content lies on the desorption boundary curve, the amount of fracture generated is larger compared to when it lies on the adsorption boundary curve. Also, fracture only nucleates after a specific drop in relative humidity, whereby the crack growth under a continuous decrease in relative humidity initially develops relatively fast, but at a certain stage decreases substantially and becomes (almost) zero when reaching a fully developed failure crack. The location and orientation of this failure crack are in accordance with in-situ observations on historical oak wood cabinets.

中文翻译：

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木材中气候引起的断裂和变形的数值模拟：应用于历史博物馆物品

摘要 使用热-湿-机械模型研究了室内气候变化（相对湿度、温度）下橡木博物馆物品的损坏情况。该模型结合了水分吸附滞后和离散开裂的影响，并使用交错更新程序在有限元框架内实施。进行吸附素实验以校准水分吸附滞后模型。耦合公式的基本特征通过求解基本橡木样本在一系列复杂性不断增加的热-湿-机械载荷条件下的响应得到逐步证明。这些模拟表明，与相对湿度变化引起的贡献相比，代表室内博物馆条件的热变化产生的变形和断裂是微不足道的。随后，分析了橡木橱柜门板在相对湿度从 60% 下降到 20% 的情况下的吸湿机械响应，并将结果与​​实验结果进行了比较。数值和实验结果吻合良好，表明在楔形端与垂直板的连接处，受抑制的湿收缩最大，刺激了局部裂纹的发展。只有在橡木达到一定年龄后，才容易断裂，因为老化的影响会导致橡木垂直于纹理方向的抗拉强度随着时间的推移而降低。此外，当初始含水量位于解吸边界曲线上时，与位于吸附边界曲线上时相比，产生的裂缝量更大。此外，断裂仅在相对湿度特定下降后成核，因此在相对湿度持续下降下裂纹扩展最初发展​​相对较快，但在某个阶段大幅下降，并在达到完全发展的破坏裂纹时（几乎）变为（几乎）为零。这种破坏裂缝的位置和方向与对历史橡木橱柜的现场观察一致。与位于吸附边界曲线上时相比，产生的裂缝量更大。此外，断裂仅在相对湿度特定下降后成核，因此在相对湿度持续下降下裂纹扩展最初发展​​相对较快，但在某个阶段大幅下降，并在达到完全发展的破坏裂纹时（几乎）变为（几乎）为零。这种破坏裂缝的位置和方向与对历史橡木橱柜的现场观察一致。与位于吸附边界曲线上时相比，产生的裂缝量更大。此外，断裂仅在相对湿度特定下降后成核，因此在相对湿度持续下降下裂纹扩展最初发展​​相对较快，但在某个阶段大幅下降，并在达到完全发展的破坏裂纹时（几乎）变为（几乎）为零。这种破坏裂缝的位置和方向与对历史橡木橱柜的现场观察一致。但在某个阶段，当达到完全发展的破坏裂纹时，会大幅减少并变为（几乎）为零。这种破坏裂缝的位置和方向与对历史橡木橱柜的现场观察一致。但在某个阶段，当达到完全发展的破坏裂纹时，会大幅减少并变为（几乎）为零。这种破坏裂缝的位置和方向与对历史橡木橱柜的现场观察一致。