Internal interfacial debonding (IID) phenomena on sandwich façade insulated panels are detected and tracked by acoustic emission (AE). The panels are made of a thin and lightweight cementitious composite skin. In the lab, the panels are tested under incremental bending simulating service loads (i.e., wind). Local (up to 150 mm wide) skin-core detachments are reported in the early loading stage (at 5% of ultimate load) and are extensively investigated in this study, since IID can detrimentally affect the long-term durability of the structural element. A sudden rise in the AE hits rate and a shift in the wave features (i.e., absolute energy, amplitude, rise time) trends indicate the debonding onset. AE source localization, validated by digital image correlation (DIC) principal strains and out-of-plane full-field displacement mapping, proves that early debonding occurs instantly and leads to the onset of cracks in the cementitious skin. At higher load levels, cracking is accompanied by local debonding phenomena, as proven by RA value increases and average frequency drops, a result that extends the state-of-the-art in the fracture assessment of concrete structures (Rilem Technical Committee 212-ACD). Point (LVDT) and full-field (AE/DIC) measurements highlight the need for a continuous and full-field monitoring methodology in order to pinpoint the debonded zones, with the DIC technique accurately reporting surface phenomena while AE offers in-volume damage tracking.

中文翻译：

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水泥纤维增强夹芯保温板内部，早期载荷界面剥离的揭示

通过声发射（AE）检测并跟踪夹层外墙保温板的内部界面剥离（IID）现象。面板由薄而轻的水泥复合表皮制成。在实验室中，在模拟服务负载（例如风）的增量弯曲下对面板进行测试。据报道，在早期负荷阶段（极限负荷的5％），局部（最大150毫米宽）皮芯脱落，并且由于IID会对结构元件的长期耐久性产生不利影响，因此对此研究进行了广泛研究。AE命中率的突然升高和波浪特征（即绝对能量，振幅，上升时间）的变化趋势表明脱胶开始。AE源定位，通过数字图像相关（DIC）主应变和平面外全场位移映射验证，证明早期脱胶会立即发生并导致胶结性皮肤出现裂纹。在较高的载荷水平下，开裂伴随着局部剥离现象，如RA值增加和平均频率下降所证明的那样，其结果扩展了混凝土结构断裂评估中的最新技术（Rilem技术委员会212-ACD ）。点（LVDT）和全场（AE / DIC）测量突出显示了需要连续和全场监视方法以查明脱胶区域的能力，DIC技术可准确报告表面现象，而AE可提供体积内损坏跟踪。正如RA值增加和平均频率下降所证明的那样，这一结果扩展了混凝土结构断裂评估的最新技术（Rilem技术委员会212-ACD）。点（LVDT）和全场（AE / DIC）测量突出显示了需要连续和全场监视方法以查明脱胶区域的能力，DIC技术可准确报告表面现象，而AE可提供体积内损坏跟踪。正如RA值增加和平均频率下降所证明的那样，这一结果扩展了混凝土结构断裂评估的最新技术（Rilem技术委员会212-ACD）。点（LVDT）和全场（AE / DIC）测量突出显示了需要连续和全场监视方法以查明脱胶区域的能力，DIC技术可准确报告表面现象，而AE可提供体积内损坏跟踪。