| 1. |
- Abbas, Zeshan, et al.
(författare)
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Influence of Patterns on Mechanical Properties of Ultrasonically Welded Joints in Copper Substrate and Wire
- 2024
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Ingår i: Metals and Materials International. - : Springer Nature. - 1598-9623 .- 2005-4149.
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasonic wire welding is considered a method of choice for creating reliable interconnects in electronics industry including aerospace, batteries and electric vehicles. In this paper, ultrasonic welding tests between EVR252 copper wire and substrate are carried out. Novel pattern morphologies are machined on substrates to explore its influence on mechanical properties of welded joint. Patterns are divided into three different categories e.g., original surface, vertical and horizontal shapes. Cracks, microstructure strength and tensile properties of welded joint are studied and its joining mechanism is analysed. Compared with the reference substrate (S1), the welded joint performance of the longitudinal patterns (S2, S3, S4) has been improved, among which the longitudinal pattern (S4) has the most significant improvement (+ 15%). Likewise, the performance of transverse pattern (S5) welded joints is relatively poor (− 16%). The microstructural analysis using SEM has revealed predominant joint strength on Cu wire surface while maintaining rock-like and compact properties of S4 substrate. Upper side of wire-harness compactness is frequently observed due to vertical direction of patterns on substrate and also increases the strength of welded joint. Values of failure load, failure displacement and failure energy absorption were increased by 7.9%, 72% and 35% for S2, 6.1%, 75% and 42% for S3 and 15%, 87% and 113% for S4 compared to S1. Failure modes of welded joints are mainly characterized into: 1-poor ductility or rupture (no deformation) failure in vertical 3-line pattern joints 2-cylindrical deep holes failure in vertical 3-line zigzag pattern joints and 3-bulging effect failure in horizontal 3-line zigzag pattern joints. Point and line scans EDS measurement were performed to investigate weaker and stable trends of different locations in welded joints. In S4 substrate, 17.9% carbon content at the position of welded joint was investigated, leading to content of less oxides and fraction impurities. However, S1 weld zone contains 38.7% carbon content which can weaken welded joint and reduce durability. Graphical Abstract: (Figure presented.). © The Author(s) under exclusive licence to The Korean Institute of Metals and Materials 2024.
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| 2. |
- Abbas, Zeshan, et al.
(författare)
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Surface-conformed approach for mechanical property analysis using ultrasonic welding of dissimilar metals
- 2024
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer Science+Business Media B.V.. - 0268-3768 .- 1433-3015. ; 132:7-8, s. 3447-3466
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, dissimilar aluminum (Al) and copper (Cu) metals were joined together using ultrasonic metal welding (USMW), a solid-state welding technology. From the perspective of increasing the base metal welding contact area, the Cu/Al mating surface was innovatively prepared and ultrasonically welded. A comprehensive analysis was carried out on the forming quality, welding process temperature, interface structure, and mechanical properties of the welded joint. Defect-free and squeezed welds were successfully achieved by machining novel patterns especially C4-2. The results indicated that the reference joint can withstand higher loads, but its failure mode is very unstable. Failure may occur at welded interface and on the aluminum plate which is not good for actual production applications. Welded strength of reference joint was 4493 N, and the welded strength of C4-2 joint was 3691 N. However, microscopic analysis discovered that the welded joint internal morphology in C4-2 was more stable and hardest. C4-2 joint has successfully achieved higher tensile strength and stability under failure displacement of 38% which is higher than C4-1 joint. All welded joint failures occurred on aluminum plate, indicating that the joint strength is higher than that of bottom plate. This is attributed to unique structural design of chiseled joint and lesser thickness. SEM–EDS results investigated that the C4-2 joint can transfer more energy to area under welding head which provides welded joint with robust diffusion capacity. The transition layer has a higher thickness while the energy transferred to area away from welding head was smaller. Thickness of transition layer is significantly reduced and reference joint has similar diffusion characteristics. Conversely, the thickness of the transition layer at the corresponding position is smaller than that of pattern morphology. This is due to overall smaller thickness of the pattern joint which is more conducive to the transfer of welding energy. The surface-conformed approach and comprehensive temperature analysis provide a new understanding of USMW in dissimilar welded metals. © The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2024.
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| 3. |
- Fan, Teng, et al.
(författare)
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Microstructural and Mechanical Characteristics Examination of Ultrasonically Welded Joints Using Orthogonal Experimentation
- 2024
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Ingår i: International Journal of Precision Engineering and Manufacturing (IJPEM). - : The Korean Society for Precision Engineering and Manufacturing (KSPE). - 2234-7593 .- 2005-4602.
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present an investigation of ultrasonic welding performance for 25 mm2 copper wire and T2 copper plate across various welding parameters using orthogonal experimentation. The objective of this work was to explore the influence of operational parameters on the resulting welds. A comprehensive study of the mechanical properties and microstructure of the copper wire-to-copper plate joint was carried out using a series of sophisticated instruments. It includes a universal tensile machine, resistance measuring equipment, SEM, EDS and temperature measuring tool. This multifaceted approach enabled a detailed analysis of the joint's integral features and properties. This provides further insight into its performance and durability. Findings indicate that welding pressure has the most significant effect on welded joints. The optimal combination of parameters is achieved with the welding energy set at 6000 J, the welding amplitude at 85% and the welding pressure at 260 kPa. In different sets of welding parameters, joint strength is positively related to welding parameters and increases with increasing welding parameters. Joint resistance decreases with increasing joint tensile load and conductivity can be used to evaluate ultrasonic welding. It has been found that the development of the welded joint is achieved gradually in a direction moving inwards from the welding tool head, exhibiting a methodical forming process. Three distinct failure modes are observed in welded joints such as joint pullout, joint tearing and busbar breakage. The peak temperature during the welding process was recorded at 373 °C which indicates that the ultrasonic welding is a solid state connection. © The Author(s), under exclusive licence to Korean Society for Precision Engineering 2024.
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| 4. |
- Hong, Wanlu, et al.
(författare)
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Low-temperature mechanical properties of slotted and normal terminals using ultrasonic wire harness welding
- 2024
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Ingår i: Welding in the World. - : Springer Science+Business Media B.V.. - 0043-2288 .- 1878-6669. ; 68:8, s. 2057-2069
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Tidskriftsartikel (refereegranskat)abstract
- The ultrasonic metal welding technology is widely promoted as a new connection approach in the field of current energy vehicle wiring harness connection. In the present investigation, low-temperature mechanical properties of slotted and normal terminals were studied. The EVR 25 mm2 copper wires are selected for welding using ultrasonic wire harness welding with two different structures of T2 copper terminals. Then, a more stable joint structure under the same welding parameters is investigated through tensile tests at − 30 °C and 25 °C. The results showed that the ST joint has higher static mechanical properties than the NT joint at 25 °C and the peak load of the joint is increased. In addition, the results investigated that the performance and welded interface texture of ST joints is reliable than NT joints under 25 °C, the maximum joint load is increased by 12.93% under − 30 °C, the joint energy absorption is increased by 87.58%, and ST joint stability is better and safer in actual production applications. At the same welding parameters, the ST joints have less neck contraction at 25 °C and the ligamentous sockets are smaller and densely welded surfaces. The failures of ST joints and NT joints are investigated under the same welding parameters. The energy loss during the ST joint welding process is smaller and the welding effect is better and advantageous. The SEM findings showed that the failure of the ST joint and the NT joint is different and the tensile strength of the ST joint is greater under the same low-temperature conditions. © International Institute of Welding 2024.
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| 5. |
- Huo, Xiaole, et al.
(författare)
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Effect of ultrasonic vibration on static properties of 5A06 aluminum alloy self-piercing riveting joints
- 2023
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Ingår i: Cailiao Kexue yu Gongyi/Material Science and Technology. - : Harbin Institute of Technology. - 1005-0299. ; 31:2, s. 44-49
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Tidskriftsartikel (refereegranskat)abstract
- Self-piercing riveting process is a new connection technology with excellent performance, green, and high efficiency. It can realize the connection of the similar, different, and multi-layer light alloy sheet materials and is widely used in new energy vehicles and other fields. Furthermore, it is becoming one of the critical technologies for achieving a lightweight body. However, because the self-piercing riveting joint is a typical tight connection component, fretting damage is prone to occur under the action of alternating stress or vibration, resulting in premature joint fatigue failure. This paper uses 5A06 aluminum alloy sheet material to carry out self-piercing riveting and ultrasonic self-piercing riveting composite connection tests under different ultrasonic welding tool heads. Based on the tensile-shear and electron microscope tests, the effect of ultrasonic vibration on the static properties of 5A06 aluminum alloy self-piercing riveted joints was studied. The results show that: ultrasonic vibration can effectively improve the static properties of self-piercing riveted joints; the ultrasonic metal welding will form a solid phase of welding between the sheets during the composite self-piercing riveting, which is the fundamental reason for improving the mechanical properties of the combined joint; the area of ultrasonic metal welding joints affects the mechanical properties of self-piercing riveted joints; the degree of ultrasonic solid-phase welding is higher when the welding area is more extensive; ultrasonic welding will increase the temperature of the rivet, which will affect the stability of the joints to a certain extent. © 2023 Harbin Institute of Technology. All rights reserved.
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| 6. |
- Jensen, Klaus
(författare)
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三重维度的媒介：传播的三级流动
- 2015
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Ingår i: Southeast Academic Research. - 1008-1569. ; :1, s. 196-204
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Li, Cheng-Wang, et al.
(författare)
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Comparison of mechanical properties of various joining processes of aluminum-titanium light alloy
- 2023
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Ingår i: Suxing Gongcheng Xuebao/Journal of Plasticity Engineering. - : Beijing Res. Inst. of Mechanical and Elec. Technology. - 1007-2012. ; 30:8, s. 138-145
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Tidskriftsartikel (refereegranskat)abstract
- 5A06 aluminum alloy and TA1 titanium alloy were selected for the connection tests of flow drill screw, ultrasonic clinch and ultrasonic self-piercing riveting. The influence of plate overlap methods on mechanical properties of each group of joints was studied by static tensile tests. The results show that the mechanical properties of the flow drill screw joints and the ultrasonic self-piercing riveted joints are significantly improved when the soft plate is on top during the riveting process. The plate overlap method has little effect on the ultrasonic clinch joint. Flow drill screw joints have the best cushioning and shock absorption performance, but the stability is poor, and it is more limited when applied to body structures. Ultrasonic clinch joints have low cost and simple process, but poor shear resistance and are not suitable for body structures subjected to high stress. Compared with the other two connection methods, the ultrasonic self-piercing riveted connection has the best stability, the best tensile resistance and shear stiffness, and is suitable for much of the structure in lightweight field of automobile body. © 2023 Beijing Res. Inst. of Mechanical and Elec. Technology. All rights reserved.
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| 8. |
- Li, Jie, et al.
(författare)
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Regional variations of vasomotion to G-protein coupled receptor agonists following heat stress in rats
- 2010
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Ingår i: Journal of Pharmacy and Pharmacology. - 0022-3573. ; 62:3, s. 315-322
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Tidskriftsartikel (refereegranskat)abstract
- Objectives This study was designed to compare vascular contractile and relaxing responses to G-protein coupled receptor agonists among the different regions of arteries following heat stress in rats. Methods Heat exposure was performed by increasing the internal temperature of the rats to 42 degrees C for 15 min. After heat stress for 48 h, a rnyograph system was used to monitor the contractile responses in rat renal, femoral and mesenteric arteries to agonists of endothelin type B (ETB) receptor, endothelin type A (ETA) receptor, serotonin receptor and alpha-adrenoceptor, respectively. In addition, calcitonin gene-related peptide (CGRP)-induced vasodilation was studied. Key findings The results showed that heat stress induced decreased contractions mediated by alpha-adrenoceptors and serotonin receptors (at lower concentration), while it increased contraction mediated by endothelin ETB receptors and enhanced relaxation mediated by CGRP receptors in the renal artery. Heat stress increased contractions mediated by endothelin ETB receptors, endothelin ETA receptors and alpha-adrenoceptors in the femoral artery. In the mesenteric artery, heat stress increased contractions mediated by endothelin ETB and serotonin receptors and relaxation mediated by CGRP receptors. Conclusions The vasomotor responses to the G-protein coupled receptor agonists with altered vascular contractions and relaxations were different in rat renal, femoral and mesenteric arteries after heat stress. This might have contributed to the redistribution of blood flow and aids understanding of the preconditioning phenomenon.
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| 9. |
- Liang, Feng, et al.
(författare)
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LAD-Net : A lightweight welding defect surface non-destructive detection algorithm based on the attention mechanism
- 2024
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Ingår i: Computers in industry (Print). - : Elsevier. - 0166-3615 .- 1872-6194. ; 161
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasound welding technology is widely applied in the field of industrial manufacturing. In complex working conditions, various factors such as welding parameters, equipment conditions and operational techniques contribute to the formation of diverse and unpredictable line defects during the welding process. These defects exhibit characteristics such as varied shapes, random positions, and diverse types. Consequently, traditional defect surface detection methods face challenges in achieving efficient and accurate non-destructive testing. To achieve real-time detection of ultrasound welding defects efficiently, we have developed a lightweight network called the Lightweight Attention Detection Network (LAD-Net) based on an attention mechanism. Firstly, this work proposes a Deformable Convolution Feature Extraction Module (DCFE-Module) aimed at addressing the challenge of extracting features from welding defects characterized by variable shapes, random positions, and complex defect types. Additionally, to prevent the loss of critical defect features and enhance the network's capability for feature extraction and integration, this study designs a Lightweight Step Attention Mechanism Module (LSAM-Module) based on the proposed Step Attention Mechanism Convolution (SAM-Conv). Finally, by integrating the Efficient Multi-scale Attention (EMA) module and the Explicit Visual Center (EVC) module into the network, we address the issue of imbalance between global and local information processing, and promote the integration of key defect features. Qualitative and quantitative experimental results conducted on both ultrasound welding defect data and the publicly available NEU-DET dataset demonstrate that the proposed LAD-Net method achieves high performance. On our custom dataset, the F1 score and mAP@0.5 reached 0.954 and 94.2%, respectively. Furthermore, the method exhibits superior detection performance on the public dataset. © 2024 Elsevier B.V.
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| 10. |
- Lin, Sen, et al.
(författare)
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Non-destructive monitoring of forming quality of self-piercing riveting via a lightweight deep learning
- 2023
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Self-piercing riveting (SPR) has been widely used in automobile body jointing. However, the riveting process is prone to various forming quality failures, such as empty riveting, repeated riveting, substrate cracking, and other riveting defects. This paper combines deep learning algorithms to achieve non-contact monitoring of SPR forming quality. And a lightweight convolutional neural network with higher accuracy and less computational effort is designed. The ablation and comparative experiments results show that the lightweight convolutional neural network proposed in this paper achieves improved accuracy and reduced computational complexity. Compared with the original algorithm, the algorithm's accuracy in this paper is increased by 4.5[Formula: see text], and the recall is increased by 1.4[Formula: see text]. In addition, the amount of redundant parameters is reduced by 86.5[Formula: see text], and the amount of computation is reduced by 47.33[Formula: see text]. This method can effectively overcome the limitations of low efficiency, high work intensity, and easy leakage of manual visual inspection methods and provide a more efficient solution for monitoring the quality of SPR forming quality. © 2023. The Author(s).
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| 11. |
- Lun, Zhao, et al.
(författare)
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Skip-YOLO : Domestic Garbage Detection Using Deep Learning Method in Complex Multi-scenes
- 2023
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Ingår i: International Journal of Computational Intelligence Systems. - : Springer Science+Business Media B.V.. - 1875-6891 .- 1875-6883. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- It is of great significance to identify all types of domestic garbage quickly and intelligently to improve people's quality of life. Based on the visual analysis of feature map changes in different neural networks, a Skip-YOLO model is proposed for real-life garbage detection, targeting the problem of recognizing garbage with similar features. First, the receptive field of the model is enlarged through the large-size convolution kernel which enhanced the shallow information of images. Second, the high-dimensional features of the garbage maps are extracted by dense convolutional blocks. The sensitivity of similar features in the same type of garbage increases by strengthening the sharing of shallow low semantics and deep high semantics information. Finally, multiscale high-dimensional feature maps are integrated and routed to the YOLO layer for predicting garbage type and location. The overall detection accuracy is increased by 22.5% and the average recall rate is increased by 18.6% comparing the experimental results with the YOLOv3 analysis. In qualitative comparison, it successfully detects domestic garbage in complex multi-scenes. In addition, this approach alleviates the overfitting problem of deep residual blocks. The application case of waste sorting production line is used to further highlight the model generalization performance of the method. © 2023, Springer Nature B.V.
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| 12. |
- Peng, Changqing, et al.
(författare)
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LightFlow : Lightweight unsupervised defect detection based on 2D Flow
- 2024
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9456 .- 1557-9662. ; 73
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Tidskriftsartikel (refereegranskat)abstract
- In the industrial production process, unsupervised visual inspection methods have obvious advantages over supervised visual inspection methods due to the scarcity of defect samples, annotation costs and the uncertainty of defect generation. Currently, unsupervised defect detection and localization methods have demonstrated significant improvements in detection accuracy to find numerous applications in industrial inspection. Nonetheless, the complexity of these methods limits their practical application. In this paper, we integrate the FastFlow model plugin as a probability distribution by introducing a simpler and lightweight CNN pre-trained backbone. Concurrently, various training strategies are employed to optimize the 2D Flow module within the Lightweight unsupervised flow model (LightFlow). Notably, the number of model parameters in the LightFlow model is only 1/4 of the original model size of the typical Vision Transformer (ViT) model CaiT. Thereby, this offers heightened training efficiency and speed. Therefore, extensive experimental results on three challenging anomaly detection datasets (MVTec AD, VisA, and BTAD) using various CNN backbones and multiple current state-of-the-art vision algorithms demonstrate the effectiveness of our approach. Specifically, the existing method can achieve 99.1% and 95.2% image-level AUROC (area under the receiver operating characteristic) in MVTec AD and VisA, respectively. IEEE
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| 13. |
- Su, Jianxiong, et al.
(författare)
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Microscopic mechanism of ultrasonically welded joints : The role of terminal roughness and wire diameter
- 2024
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Ingår i: Materials Characterization. - : Elsevier. - 1044-5803 .- 1873-4189. ; 214
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Tidskriftsartikel (refereegranskat)abstract
- The ultrasonic welding technology is widely promoted as a new connection approach in the field of current energy vehicle wiring harness connection. In this paper, three kinds of 25mm2 copper wire harnesses with different wire diameters and T2 copper terminals with different surface roughness were welded by ultrasonic welding. The mechanical properties of the joints were investigated by tensile experiments and the microstructure of joints was characterised using SEM and EBSD techniques. Excessive roughness increases plastic deformation at the weld interface during ultrasonic welding. This increases the dislocation density at the weld interface and refines the grain size. However, at the same time it inhibits recrystallisation to a certain extent. The lower roughness facilitates recrystallisation, but the low density of HAGBs makes the interface susceptible to slip in extended crystallographic plane and direction. Appropriate roughness allows the weld interface to generate fine equiaxed grains and a high density of HAGBs. This facilitates the obstruction of dislocation movement and improves the strength of joint. In addition, the high porosity of a longitudinal cross-section of the conductor with its small diameter was investigated. This results in a large number of wires remaining on the terminals when force is applied. It was determined that the larger a diameter of wire, the higher a cross-sectional porosity. The copper wire breaks at a weak point in cross-section when the force is applied, resulting in the entire wire being left on terminal. At a wire diameter of 0.2 mm, the porosity of a cross-section reaches an equilibrium and the strength of joint is even higher than the strength of material itself, resulting in the joint pulling off. The maximum strength reaches 4703.77 N. © 2024
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| 14. |
- Ye, Kai, et al.
(författare)
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Static mechanical properties and failure behaviors of self-piercing riveted joints in aluminum alloy 5A06 after aging
- 2024
-
Ingår i: Thin-walled structures. - : Elsevier. - 0263-8231 .- 1879-3223. ; 201
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Tidskriftsartikel (refereegranskat)abstract
- This paper conducts an investigation on the static mechanical properties and failure behavior of self-piercing riveted joints in aluminum alloy 5A06 after being subjected to the aging process. The study involves three distinct categories of joint specimens: original specimens, 1-year aged specimens and 1-year aged specimens that have been additionally heat-treated at 200 °C. The research findings affirm that strain aging is responsible for a reduction in the peak strength of the joints. Furthermore, the weakest failure chain within the self-piercing riveted joint shifts towards the upper sheet due to a more significant reduction in internal stress experienced by the upper plate. This leads to a failure model characterized by upper sheet pull-off. Through Weibull distribution analysis, it has been established that the 5 % lower limit value for the strength of the SPR joint experiences an 86 % decline following 1-year aging. In practical terms, this means that for a vehicle structure with 7000 riveting points will lose an overall structural strength equivalent to the initial strength of 1000 riveting points within one year. © 2024 Elsevier Ltd
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| 15. |
- Zhao, Lun, et al.
(författare)
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A Hybrid Crack Detection Approach for Scanning Electron Microscope Image Using Deep Learning Method
- 2021
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Ingår i: Scanning. - : Wiley-Hindawi. - 0161-0457 .- 1932-8745.
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Tidskriftsartikel (refereegranskat)abstract
- The scanning electron microscope (SEM) is widely used in the analysis and research of materials, including fracture analysis, microstructure morphology, and nanomaterial analysis. With the rapid development of materials science and computer vision technology, the level of detection technology is constantly improving. In this paper, the deep learning method is used to intelligently identify microcracks in the microscopic morphology of SEM image. A deep learning model based on image level is selected to reduce the interference of other complex microscopic topography, and a detection method with dense continuous bounding boxes suitable for SEM images is proposed. The dense and continuous bounding boxes were used to obtain the local features of the cracks and rotating the bounding boxes to reduce the feature differences between the bounding boxes. Finally, the bounding boxes with filled regression were used to highlight the microcrack detection effect. The results show that the detection accuracy of our approach reached 71.12%, and the highest mIOU reached 64.13%. Also, microcracks in different magnifications and in different backgrounds were detected successfully.
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| 16. |
- Zhao, Lun, et al.
(författare)
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Performance analysis of similar and dissimilar self-piercing riveted joints in aluminum alloys
- 2023
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Ingår i: Composites and Advanced Materials. - : Sage Publications. - 2634-9833. ; 32
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Tidskriftsartikel (refereegranskat)abstract
- In this work, similar (2A12) and dissimilar (6061) aluminum alloy sheets are validly joined using self-piercing rivet process. A quasi-static experiment is proposed to investigate the mechanical behaviors, failures mode, and mechanism of the different joints. Moreover, a method based on deep learning algorithm is anticipated to detect the appearance defects of the SPR welded joints. The results indicated that 2A12 joints of similar sheets contained the advantageous static strength and 6061 similar sheet joints had superior anti-vibration performance conducts. The joints with 6061-2A12 sheets introduced the most decent and comprehensive mechanical properties. The main failure mode of 2A12 similar sheet joints was substrate fracture. The performance of the substrate affects the failure mode of the joint and the plasticity of the substrate is better. When the time comes, the failure mode is mostly pull-off failure. Poor plasticity of the substrate can easily lead to substrate breakage. The reason for joint pull-off and button fall-off failure is that there is large plastic deformation in the lower plate of the joint and the mechanical internal locking structure is damaged. 2A12 substrate breakage belongs to a composite fracture that combines intergranular fracture and microvoid aggregation type fracture. The area of the 6061 substrate near the edge of the sample is shear fracture and the area near the center of the sample thickness is dominated by microvoid aggregation type normal fracture. The effectiveness of the method was verified by conducting a series of experiments and the detection accuracy of the method can reach about 90%. The detection speed was as high as 50 frames per second (FPS), which can effectively solve the problem that the rivet quality was difficult to monitor.
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| 17. |
- Zhao, Lun, et al.
(författare)
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YOLOv8-QR : An improved YOLOv8 model via attention mechanism for object detection of QR code defects
- 2024
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Ingår i: Computers & electrical engineering. - : Elsevier. - 0045-7906 .- 1879-0755. ; 118
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Tidskriftsartikel (refereegranskat)abstract
- Defect detection in Quick Response (QR) codes has important implications for downstream tasks. However, QR code defects include small objects and complex backgrounds, which makes their recognition effect poor. To address the above problems, we proposed a model based on YOLOv8, called YOLOv8-QR, to detect QR code defects. Specifically, first, the non-local attention (Non-local) module is introduced into the backbone of the YOLOv8 to enhance the interactive ability of the feature. The Non-local captures the correlation information of long-distance dependencies between features by calculating the attention weight between any positions. In addition, the contextual information required for representation learning of different defective objects is different. To extract multi-scale features, a Large Selective Kernel Network (LSKNet) was introduced. LSKNet dynamically adjusts the convolution receptive field of the neck fusion network and effectively uses the receptive field to capture the background information of different objects, thereby improving the representation ability of the model. To improve the defect detection accuracy of small objects in QR codes, the Normalized Gaussian Wasserstein Distance (NGWD) is introduced to replace the Intersection over Union (IoU) optimization function that is sensitive to the position deviation of objects and is not conducive to the regression of multi-scale objects. To verify the effectiveness of the model, the QR dataset was constructed and a series of experiments were conducted based on this dataset. The results show that the mAP50 and mAP50:95 of the YOLOv8-QR reach 95.5% and 65%, which are 3.8% and 2.3% higher than YOLOv8 respectively. The proposed YOLOv8-QR can better adapt to the needs of QR code defect detection in actual industrial environments. Our code is available at https://github.com/Code-of-Liujie/YOLOv8-QR.git. © 2024
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| 18. |
- Zhao, Yun, et al.
(författare)
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Precise separation of spent lithium-ion cells in water without discharging for recycling
- 2022
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Ingår i: Energy Storage Materials. - : Elsevier. - 2405-8289 .- 2405-8297. ; 45, s. 1092-1099
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Tidskriftsartikel (refereegranskat)abstract
- New methods for recycling lithium-ion batteries (LIBs) are needed because traditional recycling methods are based on battery pulverization, which requires pre-treatment of tedious and non-eco-friendly discharging and results in low efficiency and high waste generation in post-treatment. Separating the components of recycled LIB cells followed by reuse or conversion of individual components could minimize material cross-contamination while avoiding excessive consumption of energy and chemicals. However, disposing of charged LIB cells is hazardous due to the high reactivity of lithiated graphite towards cathode materials and air, and the toxicity and flammability of the electrolytes. Here we demonstrate that the disassembly of charged jellyroll LIB cells in water with a single main step reveals no emissions from the cells and near perfect recycling efficiencies that exceed the targets of the US Department of Energy and Batteries Europe. The precise non-destructive mechanical method separates the components from jellyroll cell in water, avoiding both uncontrollable reactions from the anode and burning of the electrolyte, while allowing only a limited fraction of the anode lithium to react with water. Recycling in this way allows the recovery of materials with a value of ∼7.14 $ kg−1 cell, which is higher than that of physical separation (∼5.40 $ kg−1 cell) and much greater than the overall revenue achieved using element extraction methods (<1.00 $ kg−1 cell). The precise separation method could thus facilitate the establishment of a circular economy within the LIB industry and build a strong bridge between academia and the battery recycling industry.
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| 19. |
- Zixin, Guo, et al.
(författare)
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The effects of three profiles on the mechanical properties and grain size of self-piercing riveting joints using ultrasonic welding
- 2023
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer Science+Business Media B.V.. - 0268-3768 .- 1433-3015. ; 129:11-12, s. 4869-4882
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasonic welding has become a key joining approach in batteries and energy vehicles. This work reports the optimization in static property and stability of self-piercing riveting joints which is becoming the most versatile way to join microstructures. Tool heads of three different knurling profiles (e.g., A, B, and C) are used to perform ultrasonic composite with riveting. Based on tensile-shear tests, SEM, EDS, XRD, and Vickers microhardness analysis were conducted to investigate the comparative study of the fracture morphology, element distribution, phase structure, and hardness. The results indicated that all three types of knurling generate solid phase welding at the sheet joints. Thus, it improved the forming quality and mechanical properties of self-piercing riveting joints. The C-shaped welding tool head has advantageous effect on optimizing the mechanical properties of joints. Further, it enhanced the average peak load by 25.6%, the average failure displacement by 31.1%, and the average energy absorption by 88.8%. The microscopic results showed that a large amount of oxides are precipitated at the edge of welding joints when the B-shape knurling tool is used. The distribution of the hardness value of joints horizontal line is “M” shape. Besides, the coarse grains in the joint area and the interplanar space increase significantly after ultrasonic welding which softens the sheet. © 2023, The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.
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| 20. |
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