Daissè Gilda, Abali Bilen Emek, Wan-Wendner Roman
Christian Doppler Laboratory, University of Natural Resources and Life Sciences Vienna, Peter-Jordanstr. 82, Vienna, 1190 Austria.
Division of Applied Mechanics, Uppsala University, Box 35, Uppsala, 751 03 Sweden.
Appl Compos Mater (Dordr). 2024;31(2):739-764. doi: 10.1007/s10443-023-10184-y. Epub 2023 Dec 30.
Structural adhesives characterized a turning point in the post-connection of structural elements due to their excellent performances and ability to transfer stress without losing their integrity. These materials are typically particle-reinforced composites made by a thermoset polymer matrix and fillers. During the in-situ application of this material, the thermal activation of the polymer is typically not possible, leading to an undefined degree of cure and therefore to a variation of the mechanical performance over time. This altering means that after applying a sustained load on a bonded anchor system installed at regular temperature, the adhesive changes material properties. Ample studies convince that the progressive increase of the degree of cure of the thermosetting polymer leads to higher strength and stiffness. However, limited studies have been dedicated to the post-curing effects on the long-term behavior. The main goal of this work is to investigate the tensile and shear creep behavior of two commercially available structural adhesives and the influence of curing conditions on their long-term performances. An extensive experimental campaign comprising short and long-term characterizations has been carried out on specimens subjected to three different curing and post-curing protocols, with the scope of imitating relevant in-situ conditions. The results demonstrate that structural adhesives cured at higher temperatures are less subjected to creep deformations. As a material equation, the generalized Kelvin model is utilized to fit the tensile and shear creep data, and two continuous creep spectra have been selected to represent the creep behavior and facilitate extrapolations to the long-term behavior.
结构胶粘剂由于其优异的性能以及在不丧失完整性的情况下传递应力的能力，在结构元件的后期连接中具有转折点意义。这些材料通常是由热固性聚合物基体和填料制成的颗粒增强复合材料。在这种材料的现场应用过程中，聚合物的热活化通常是不可能的，这导致固化程度不确定，从而导致机械性能随时间变化。这种变化意味着在常温下安装的粘结锚固系统上施加持续载荷后，胶粘剂会改变材料性能。大量研究表明，热固性聚合物固化程度的逐渐增加会导致更高的强度和刚度。然而，关于后固化对长期性能影响的研究有限。这项工作的主要目标是研究两种市售结构胶粘剂的拉伸和剪切蠕变行为以及固化条件对其长期性能的影响。对经受三种不同固化和后固化方案的试样进行了包括短期和长期表征的广泛实验，以模拟相关的现场条件。结果表明，在较高温度下固化的结构胶粘剂较少受到蠕变变形的影响。作为材料方程，采用广义开尔文模型拟合拉伸和剪切蠕变数据，并选择了两个连续的蠕变谱来表示蠕变行为并便于外推到长期行为。
