internal sandwich panel

Huazhong University of Science and Technology, China. The plate cladding is galvanized steel sheet on both sides according to EN 10346 with organic polyester varnish with a coating thickness of 25 m. Compos. Previous studies often dealt with damage to the structural surface that could be captured by a camera or that used the structural raw displacement or acceleration data captured in experiments directly as the input data. 439, 194207. Struct. Subsequently, an improved method was also developed to identify damage to unbounded nodes (Lu et al., 2017b). (2019a). The assessed sound reduction measurement lies at approx. Health Monit. J. (2019b). doi: 10.1016/S0266-3538(03)00266-5, Yuan, W., Song, H. W., Wang, X., and Huang, C. G. (2015). MW Swall panels with visible fastening are intended for the construction of external and internal walls on a building frame. In this study, a dataset based on two damage indices is used; this dataset has a significant influence on the effectiveness of the proposed method. The parameters of the Faster RCNN are shown in Table 2. From Figure 10B, there are three areas of damage, including FCM, TCM, and HCM. By combining this with a GA, the method could determine both damage location and size. Taking HCM as an example, the five cases are listed in Table 3. 2022 PortaFab Corporation All Rights Reserved. For surface cracks in composite laminates, Hu et al. Compos, B. When detecting damage in large structures, the method cannot effectively identify small debonding, which has little influence on the low-frequency range of an FRF. A laser Doppler vibrometer (Polytec, PSV-400) generated the excitation signal and measured the structural response. To verify the proposed analytical model, experiments were carried out in which pyramidal SPTCs (Figure 3A) were used. Struct. where E and F are the numbers of the columns and rows of the measuring points; P1 and P2 are the beginning and ending order modes, respectively, in the practical case; and pm is defined as the weight coefficient of the p-th component and is expressed in Equation (7). Indus. doi: 10.1109/TPAMI.2016.2577031, Seguel, F., and Meruane, V. (2018). This website use cookies to improve our products and your experience on our website by evaluating the use of our website, products and services, to personalize content, to provide social media features and to analyze our traffic. Kareiviu str. (B) Multiple-damage case. Material properties and geometrical information. (2018) proposed an autoencoder-based framework for damage identification, which could support deep neural networks and which could be used to obtain optimal solutions for pattern recognition problems of a highly non-linear nature. CH: project administration. The training loss curves of DI-1 and DI-2. IEEE Trans. The training images were obtained by means of a low-cost smart mobile phone, demonstrating that DL has the potential to be applied in practical damage identification. Struct. Therefore, in this study, analytical models with random damage features, verified by experiments, are used as they are able to consider all possible damage features. Debonding detection of honeycomb sandwich structures using frequency response functions. YW, JB, and LL: software. (2015) proposed a baseline-free damage localization method based on uniform load surface curvature, a gapped smoothing method, and the Teager energy operator to detect truss bar damage. Smart Mater. 333, 52995311. Compared with traditional structure styles, such as beams or plates, internal damage identification of SPTCs is more difficult: 1) Internal damage, such as unbound nodes, is shielded by the face sheets, which hinders direct visible inspection, so a vibration-based identification method may be an important choice. From Figure 5A, when the DE increases from HCM to TCM or FCM, the characteristics of the identified damage, such as the color gradient or area, change a little, especially for HCM, OCM, or FCM. Liu et al. Deep Learing-based crack damage detection using convolutional neural networks. Experimental validation of modal strain energies based damage identification method for a composite sandwich beam. IEEE Trans. According to the variations in the vibration characteristics, the damage features can be identified. (2013) used non-linear acoustics to detect impact damage in a composite chiral sandwich panel. doi: 10.1016/S0020-7683(02)00241-X, Guo, T., Wu, L. P., Wang, C. J., and Xu, Z. L. (2020). Sound Vib. This conclusion is in accordance with previous studies. doi: 10.2514/1.J053246, Yuan, W., Wang, X., Song, H. W., and Huang, C. G. (2014). The statistical results also reveal that damage indices play a very important role in the identification process. For DI-2, it can be seen that the loss value tends to be stable when the iteration is around 1,000 times, and the final loss value is stable at around 0.1. Sandwich panel with increased fire resistance classinsPIRe FIREconsists of 2 galvanized steel claddings and coated with organic polyester varnish. 116, 278290. The structural modal information was obtained by analyzing the excitation and structural response signal. Damage identification of low-density material-filled sandwich panels with truss core based on vibration properties. Comparing Figure 5A with Figure 5B, it can be seen that the extracted feature based on DI-1 is more obvious than that based on DI-2 when DE is small (HCM and OCM). Finally, the input dataset, including massive and diverse samples, was built. Hg, A. Detailed data is available in the section "For designers - flashing". DE includes HCM, OCM, TCM, and FCM, and the corresponding parameter DE is set to 1, 2, 3, and 4, respectively. Struct. Eigenvalue analysis on fluidelastic instability of a rotated triangular tube array considering the effects of two-phase flow. Cladding PanelsLow cost, light weight panels featuring a textured exterior finish. When DE is large, DI-2 is better than DI-1. Sci. Caffe, a DL framework, was used to conduct the training process as it has been widely applied in DL and machine learning, such as computer vision, speech recognition, image feature coding, and information retrieval. Two-phase flow-induced instability and nonlinear dynamics of a single tube in tube bundles in the transverse direction. Seguel and Meruane (2018) proposed four damage indices, including mode shape curvatures, uniform load surface, modal strain energy, and gapped smoothing, to evaluate the debonding damage of an aluminum honeycomb sandwich panel. All authors contributed to the article and approved the submitted version. Veneer PanelsLow cost, light weight panels featuring a smooth exterior finish. LL and CL: formal analysis. The panels can be installed both in a vertical and horizontal arrangement. An analytical model verified by experiments based on a laser vibrometer is used to obtain raw data, which can generate various levels of damage inside the two face sheets. Based on the proposed analytical models and the two damage indices, data in the cases of single and multiple damage are obtained. Structural vibration-based classification and prediction of delamination in smart composite laminates using deep learning neural network. Table 5. The procedure used by the analytical model is shown in Figure 2B. The trained CNN was combined with a sliding window technique to scan any image size. The flashings are protected against damage by foiling the top side. Compos. Obtaining more data is always the best way to make a neural network model generalize better, although the amount of data is usually limited in practice. Of the 2018 samples obtained, 50% were set as the training set and 50% were set as the testing set. However, information from videos or images is normally very limited and cannot cover all possible damage features. NEW! The specimens were excited by a JZK-50 shaker. J. Analysis on streamwise fluidelastic instability of rotated triangular tube arrays subjected to two-phase flow. The use of insPIRe U sandwich panels with invisible fastening improves the visual effect of the building's facade. By combining this with an analytical model, a dataset of specimens with various defects was collected and used as the input for the neural networks. Using the frequency response function (FRF), Zhu et al. Eur. The boundary condition for the SPTC is fully clamped (CCCC). Step 4 Input the new data and evaluate the trained model. They ensure maximum fire protection and excellent sound reduction. Comput-aided Civ. Two damage indices are used (Li et al., 2015; Le et al., 2019) and compared; these are denoted DI-1 and DI-2. Figure 9. The training dataset is often obtained through real videos or images. According to the results for 1 shown in Figure 4, it can be seen that the trend of 1 of simulation is in accordance with the experimental results as the DE increases from 0 to 4 5. In this study, a Zend Framework (ZF) CNN was selected. (2020) reported that a novel damage identification framework was established in this study by integrating massive datasets constructed by structural transmissibility functions and a DL strategy based on one-dimensional convolutional neural networks (1D-CNNs). Table 1. In these studies, damage at different locations and of different extents are considered. Examples of the identified results. Damage localization in composite lattice truss core sandwich structures based on vibration characteristics. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. There are two steps in damage identification: first, detect if there is any damage in the structures and identify the DL; second, identify the DE and DS. In the literature, some methods have been proposed for the detection and localization of damage in sandwich structures. 10 Articles, This article is part of the Research Topic, DL Framework for Internal Damage Identification in SPTCs, Creative Commons Attribution License (CC BY). 7:301. doi: 10.3389/fmats.2020.00301. Accuracy of damage extent identification according to the statistical results. Because of the difficulty in identifying internal damage in sandwich panels (as mentioned in section introduction), damage indices are used to extract damage features. Model information of sandwich panel with truss core (SPTC). Design of a cavity between the cladding and the exterior wall of the building (or its sheath of insulation) is also significant: flames can occupy the cavity and be drawn upwards by convection, elongating to create secondary fires, and do so "regardless of the materials used to line the cavities". Numerical and experimental results. Figure 4. Compos. Therefore, in section 4.1, the capacity of the proposed method to determine the DL and DE is discussed. doi: 10.1016/j.ymssp.2019.01.010, Lai, J., Sun, L., and Li, P. Z. When the trained network identifies the DE, it is easy for the framework to identify one DE as another DE. Therefore, they can achieve different U-values depending on the core and the thickness of the panel. Concealed fasteners, which cannot be seen if viewed from the facade, contribute to panels being architecturally attractive and functional. Struct. The results revealed that different types of damage could be detected and localized accurately. A dataset that contains 300 images was used. Fiberglass CladdingEasy to clean panels are ideal for interior cladding on walls in laboratories type applications. FRP on PolystyreneIdeal for laboratories and any other application exposed to moisture or harsh cleaning agents. Also, a more complicated service environment may bring about additional problems (Lai, 2019; Lai et al., 2019a,b). Health Monit. The structural performance of near-optimized truss core panels. 172, 1328. In conclusion, according to the results in Figure 10, it can be seen that the damage can be located if the damage can be characterized in the figure, and the damage cannot be located if the damage cannot be characterized. For a given DE, DL has a significant influence on the structural vibration properties. This page was last edited on 23 June 2022, at 09:51. In contrast to the experimental specimens, in which the damage zone was prefabricated, the numerical model could simulate various cases with randomly distributed damage. Structural damage detection in real-time: implementation of 1D convolutional neural networks for SHM applications, in Structural Health Monitoring and Damage Detection, Volume 7: Proceedings of the 35th IMAC, A Conference and Exposition on Structural Dynamics. Polyisocyanurate cooling panel PIR EI 60 Fire spread B-S1, d0. Fire & SoundValue-oriented panels with excellent thermal insulation, sound deadening properties, and a class A noncombustible rating. However, for SPTCs, the weakest part is the low-density truss core, and the inside damage is covered by the face sheets and cannot be directly detected in photographs. Manufacturer has a profiling machine that allows bending of 1.25 mm thick sheet metal (maximum length of 6 m), in typical shapes from the catalog and according to the individual design of the customer. When DE is small, DI-1 is better than DI-2. During the manufacturing process or during service, damage or defects are inevitable, such as buckling of the panel (Yuan et al., 2014, 2015), breakage of the truss, burn-through of the face sheets, or truss nodes that are not bound to the face sheet. There are 15 cells along the x- and y-directions, respectively. The panels can be installed both vertically and horizontally. Experimental investigation on thermal buckling behavior of fully-clamped truss-core sandwich panels. The density of sandwich panels range from 10kg/m. This method can identify both the location and extent of damage in the faces and the core. This research was supported by the National Natural Science Foundation of China (grant nos. doi: 10.1088/0964-1726/25/11/115048, Keywords: sandwich panel with truss core, damage identification, deep learning, vibration-based damage index, feature extraction, Citation: Lu L, Wang Y, Bi J, Liu C, Song H and Huang C (2020) Internal Damage Identification of Sandwich Panels With Truss Core Through Dynamic Properties and Deep Learning. Panels can be joined to steel, reinforced concrete and wooden constructions using dedicated fasteners. From the middle and right-hand panels in Figure 8A, it can be seen that the features of HCM and OCM are similar; it is difficult for humans to identify the DE accurately, but the DL-based method could identify the location and extent accurately. Figure 5. AIAA J. Therefore, vibration-based methods, which involve many forms of damage indices that could reflect both the surface and internal damage, could be used in combination with DL for structural damage identification in SPTCs. To detect the extent of damage more accurately, some intelligent techniques, such as a genetic algorithm (GA) or convolutional neural networks (CNNs), have been combined with traditional vibration-based methods or other methods (Zhu et al., 2014; Khan et al., 2019). 59, 196203. Comparing the first line of results for DI-1 (Figure 5A) and DI-2 (Figure 5B), it can be seen that the results for HCM or OCM identified by DI-1 are better than those identified by DI-2 because the influence of small areas of damage on the structural vibration properties is small; however, when DE becomes significant, DI-2 also shows very good performance. doi: 10.1016/j.jsv.2014.05.023, Zhu, K. G., Qing, X. L. P., and Liu, P. (2016). The use of panels with a MAX core gives a lot of benefits. Electr. Struct. The healthy specimen is denoted by SD0. This demonstrates that small changes in damage features may cause large variations in the structural properties. The following list shows some of our most common panels. Then two damage indices, one with a baseline and the other without a baseline, are used to construct the input to the neural networks. Compared with DL, it is more difficult to identify the DE and DS. where iD and iU are the i-th natural frequency of the damaged and undamaged specimens, respectively. For multiple-damage cases, an analytical model with random damage features is used. Eng. OUTER WALL - VERTICAL ARRANGEMENT OF PLATES. Sound PanelsPanels with increased sound deadening characteristics for better acoustical performance. The availability of panels in two modular widths minimizes the waste generated during assembly. doi: 10.1016/j.compstruct.2016.12.028, Lu, L. L., Song, H. W., and Huang, C. G. (2017c). Therefore, the effectiveness of the two damage indices is compared. Struct. In this study, Faster RCNN (Ren et al., 2015), a framework for target recognition, is combined with a vibration-based method (section construction of the dataset) to identify internal damage features of SPTCs. Five cases for HCM identification. The details of the model are given in Table 1. Lu et al. Numerical models of the same dimensions as the experimental specimens were built to verify the analytical model. The panels can be installed both vertically and horizontally as single and multi-span wall elements. 4) The final process of damage identification relies on human judgment, which is time-consuming and subjective. 11472276, 11972033, and 11332011) and the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. Construction standards which will apply from 2021 will pay off with significantly lower energy consumption and comfort of use. CH MAX cooling panel is designed for walls and ceilings. B-Eng. Technol. Figure 1. Use tab to navigate through the menu items. The statistical results. Hardboard on PaperExtremely light weight panels with excellent strength to weight ratio. Huang et al. The details of DI-2 can be found in our previous work (Le et al., 2019). With the capacity of massive data processing, data mining, and fast training through the deep architecture of neural networks, machine learning gives an objective solution with quantitative accuracy. To consider all possible damage distributions, the parameter DL is set as a random number, with its position inside the sandwich panels. 417, 118. In this study, DS, that is, cell missing damage, is used to simulate structural damage, which is a typical form of damage for SPTCs. Most of these studies could detect and locate the damage accurately, but fewer studies have discussed quantification of the extent of damage (Kumar et al., 2009; Zhu et al., 2014; Khan et al., 2019). Infill PanelsAttractive, energy-efficient alternative or complement to glass panels. Steel on PolystyreneLight weight panels with excellent thermal resistance and a durable steel exterior. (2014). Compos. 3 m 5 m. The thickness of panels is from 40mm up to more than 200mm. (A) DI-1 and (B) DI-2. (2016) proposed a torsional guided wave method to detect debonding damage in honeycomb sandwich beams. However, based on index 2, it shows that HCM tends to be covered by an influencing factor (in Figure 5B), such as the singularity caused by the contact nodes. Even for the same damage, one index could identify it and another one may not. The panels can be mounted both vertically and horizontally as single and multi-span elements. Therefore, to identify the damage with small DE values, it is better to combine more effective indices that are sensitive to the small DE values. B., Song, H. W., Xing, X. D., and Huang, C. G. (2019). 25dB for PU elements and at approx. The lightweight cellular core can be in the form of a stochastic foam, a periodic honeycomb, a corrugated sheet, or a lattice truss (He et al., 2014; Liu et al., 2014). The results indicate that the proposed method performs well in finding cracks in concrete in realistic situations. We gain more space through thinner walls, which allow the building line to be moved closer to the plot border, we also gain a larger usable area inside the hall. (2017) used 1D-CNNs to automatically extract damage-sensitive features from the raw acceleration signals and presented the preliminary experiments that were conducted to verify the proposed method. The computing platform was Ubuntu 16.04, and all the codes were run on a server equipped with 12 Intel Core i7-6800K CPUs (3.40 GHz) and an NVIDIA GeForce GTX 1080 Ti with 11 GB of memory. Zhang et al. (2009) presented a model strain-energy two-step method for a composite sandwich beam. J. When a specimen is damaged, its stiffness or mass changes. Flowchart of the identification process. Also, compared with plates or beams, SPTCs consist of two face sheets and a truss core, meaning that the raw response data hardly reflect the structural damage information. 62, 7387. The reason for damage area 2 in Figure 10B not being identified is that the DE for damage area 2 is smaller than that for the other two damage areas. Some samples are shown in Figure 5. The defined single area of damage is in the center of the specimens. Kumar et al. doi: 10.1016/j.compstruct.2005.04.020, Huang, X. Y., Liu, Z. L., Zhang, X. Y., Kang, J. L., Zhang, M., and Guo, Y. L. (2020). insPIRe S MAXwall panels are designed for external curtain walls and internal partition walls in skeletal structures. The small DE value is easily covered by large DE values, meaning that the small DE values could not be identified or that the damage is mis-identified, as in cases 3, 4, or 5. 18, 17111721. (2002). Faster R-CNN: towards real time object detection with region proposal networks. If there was no damage in the structure, the mode shapes were smooth and continuous. By comparing the information before and after the GSM, the damage features could be extracted. Before the training process, all images were normalized to 1,491 1,501 pixels. Installation of sandwich panel can be performed in almost any weather conditions. According to the statistical results, the proposed method can identify the internal damage features DL and DE. In the analytical model, the parameters DL, DS, and DE are set as variables. Damage area 3 (TCM) is identified as HCM, and the corresponding accuracy is about 0.352, meaning that the trained network could identify that there is damage at this location but the probability of identifying it as HCM is not high. In the experiments, specimens with a single area of damage and multiple areas of damage were considered. Machine Intelligence 39, 11371149. Compos B-Eng. Therefore, for identification of internal damage in sandwich panels, the proposed method based on DI-2 is better and more effective, as it is more successful in extracting internal damage features. The proposed framework achieves a 98.3% hit rate. Because the proposed damage indices have extracted the damage feature effectively, the loss value becomes stable more quickly. F & S with FRP ExteriorExcellent cleanability on a non-combustible and sound reduction panel. In addition, for SPTCs, only the surface information can be obtained by videos or images, which does not reflect the internal damage features of SPTCs. Technol. There is evidence that when sandwich panels are used to clad a building it can contribute to the rapid spread of fire up the outside of the building itself. HCM, half-cell missing; OCM, one cell missing; TCM, two cells missing; FCM, four cells missing. From Figure 8, it can be seen that the accuracy of damage feature identification is high, no matter whether the DE is HCM, OCM, TCM, or FCM or whether the DL is in the center of the model or on the boundary edge. As the DE increases, the accuracy of identification increases. doi: 10.1016/j.compositesb.2013.12.005. 69, 16351643. The SPTC is made of stainless steel. doi: 10.1016/j.jsv.2018.09.060, Le, J., Lu, L. L., Wang, Y. NB-CNN: deep learning based crack detection using convolutional neural network and nave bayes data fusion. Andrzej, K. (2014). 39, 40934115. doi: 10.1007/978-3-319-54109-9_6, Cha, Y. J., Choi, W., and Buyukozturk, O. The relative density of the truss core was about 3%. 3) Damage identification can be classified into inversion problems, and the solutions may be non-unique. Detailed information on connectors can be found in our technical catalogues. The user will need to choose between the different sandwich panel types, depending on the requirements. The panels can be installed both in a vertical and horizontal arrangement. Therefore, the vibration characteristics (natural frequencies and mode shapes) change. YW and CL: validation. Damage assessment in a sandwich panel based on full-field vibration measurements. J. In this study, only one DS (truss core missing) is considered. Steel Fire & SoundFire & Sound panels with durable steel surfaces on front and back. No use, distribution or reproduction is permitted which does not comply with these terms. K) for mineral wool. An analytical model is then used to obtain massive raw structural data, which are verified by experiments.

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