Joint Defects Research Articles

Developments and Improvements Using Hot Wire Gas Tungsten Arc Welding – A Review

Gas tungsten arc welding (GTAW) is a high quality welding process widely used in most industries. However, the process is limited to higher welding speed and higher deposition rate. To overcome this limitation, the GTAW process is modified in such a way that filler metal is heated prior to entering into the weld pool. This heating is carried out by resistance heating. Hot wire GTAW (HW-GTAW) ensures the availability of arc energy to melt the base metal. This results in an increase in deposition rate and additionally, increases the welding speeds to a large extent. Welding is an important form of joining materials and is most significant for the application of structural components. This paper reviews the application of the hot wire technique during conventional GTA welding, thereby providing the benefits in terms of metallurgical control, energy efficiency and rate of deposition. This process has the potential to achieve high efficiency and welding faster with lower heat input. The HW-GTAW process is widely used in welding various novel materials and it is a promising alternative to the conventional GTAW process with lower heat input and narrower heat affected zones. This process not only eliminates the various defects in the weld joints but also increases productivity in industries.

Advances in Regenerative Sports Medicine Research.

Regenerative sports medicine aims to address sports and aging-related conditions in the locomotor system using techniques that induce tissue regeneration. It also involves the treatment of meniscus and ligament injuries in the knee, Achilles’ tendon ruptures, rotator cuff tears, and cartilage and bone defects in various joints, as well as the regeneration of tendon–bone and cartilage–bone interfaces. There has been considerable progress in this field in recent years, resulting in promising steps toward the development of improved treatments as well as the identification of conundrums that require further targeted research. In this review the regeneration techniques currently considered optimal for each area of regenerative sports medicine have been reviewed and the time required for feasible clinical translation has been assessed. This review also provides insights into the direction of future efforts to minimize the gap between basic research and clinical applications.

Regeneration of Articular Cartilage Using Membranes of Polyester Scaffolds in a Rabbit Model.

One promising method for cartilage regeneration involves combining known methods, such as the microfracture technique with biomaterials, e.g., scaffolds (membranes). The most important feature of such implants is their appropriate rate of biodegradation, without the production of toxic metabolites. This study presents work on two different membranes made of polyester (L-lactide-co-ε-caprolactone-PLCA) named “PVP and “Z”. The difference between them was the use of different pore precursors—polyvinylpyrrolidone in the “PVP” scaffold and gelatin in the “Z” scaffold. These were implemented in the articular cartilage defects of rabbit knee joints (defects were created for the purpose of the study). After 8, 16, and 24 weeks of observation, and the subsequent termination of the animals, histopathology and gel permeation chromatography (GPC) examinations were performed. Statistical analysis proved that the membranes support the regeneration process. GPC testing proved that the biodegradation process is progressing exponentially, causing the membranes to degrade at the appropriate time. The surgical technique we used meets all the requirements without causing the membrane to migrate after implantation. The “PVP” membrane is better due to the fact that after 24 weeks of observation there was a statistical trend for higher histological ratings. It is also better because it is easier to implant due to its lower fragility then membrane “Z”. We conclude that the selected membranes seem to support the regeneration of articular cartilage in the rabbit model.

Deep Neural Network Recognition of Rivet Joint Defects in Aircraft Products.

The mathematical statement of the problem of recognizing rivet joint defects in aircraft products is given. A computational method for the recognition of rivet joint defects in aircraft equipment based on video images of aircraft joints has been proposed with the use of neural networks YOLO-V5 for detecting and MobileNet V3 Large for classifying rivet joint states. A novel dataset based on a real physical model of rivet joints has been created for machine learning. The accuracy of the result obtained during modeling was 100% in both binary and multiclass classification.

Biomaterial Integration in the Joint: Pathological Considerations, Immunomodulation, and the Extracellular Matrix.

Defects of articular joints are becoming an increasing societal burden due to a persistent increase in obesity and aging. For some patients suffering from cartilage erosion, joint replacement is the final option to regain proper motion and limit pain. Extensive research has been undertaken to identify novel strategies enabling earlier intervention to promote regeneration and cartilage healing. With the introduction of decellularized extracellular matrix (dECM), researchers have tapped into the potential for increased tissue regeneration by designing biomaterials with inherent biochemical and immunomodulatory signals. Compared to conventional and synthetic materials, dECM-based materials invoke a reduced foreign body response. It is therefore highly beneficial to understand the interplay of how these native tissue-based materials initiate a favorable remodeling process by the immune system. Yet, such an understanding also demands increasing considerations of the pathological environment and remodeling processes, especially for materials designed for early disease intervention. This knowledge will avoid rejection and help predict complications in conditions with inflammatory components such as arthritides. This review outlines general issues facing biomaterial integration and emphasizes the importance of tissue-derived macromolecular components in regulating essential homeostatic, immunological, and pathological processes to increase biomaterial integration for patients suffering from joint degenerative diseases.

Advances in the Application of Three-dimensional Printing for the Clinical Treatment of Osteoarticular Defects.

As a promising manufacturing technology, three-dimensional (3D) printing technology is widely used in the medical field. In the treatment of osteoarticular defects, the emergence of 3D printing technology provides a new option for the reconstruction of functional articular surfaces. At present, 3D printing technology has been used in clinical applications such as models, patient-specific instruments (PSIs), and customized implants to treat joint defects caused by trauma, sports injury, and tumors. This review summarizes the application status of 3D printing technology in the treatment of osteoarticular defects and discusses its advantages, disadvantages, and possible future research strategies.

High heat flux testing for W/Cu monoblock PFUs with varying defects

The full tungsten divertor is the key component of Experimental Advanced Superconducting Tokamak (EAST) to exhaust excessive heat loads. After EAST discharge operation, defects may appear in the tungsten/copper (W/Cu) joints of W/Cu monoblock plasma-facing units (PFUs). In order to evaluate the heat removal capability and thermal fatigue stability of W/Cu PFUs with defects, the specific heat treatments are used for PFUs to introduce defects of varying degrees. Then, high heat flux (HHF) tests for PFUs with defects are performed on a 100 kW electron-beam (e-beam) device at ASIPP. The W/Cu joints defects and W surface conditions have no significant differences after HHF tests. And the test results show that the fewer defects or the larger water mass flow is, the better heat removal capability of the W/Cu monoblock has. The surface temperature of W/Cu PFUs with major defects (> 2 × 3 mm) is 12% - 17% higher than that of PFUs with minor defects (≈ 2 × 3 mm), and the minor defects PFUs is 6% - 8% higher than the non-defects one (< 2 × 3 mm). Besides, the temperature curves of three W/Cu PFUs are exponentially fitted in cooling down phase, and the obtained average thermal decay time constants are 11.1 s, 8.5 s and 7.4 s, respectively. The time constants quantitatively explain the cooling performance of PFUs with various defects, and provides a feasible method for non-destructive inspection of PFUs defects during EAST experiment. These results are conducive to understanding the relationship between damage degree and heat transfer performance, and can provide relevant basis for improving the acceptance criterion of qualified W/Cu PFUs.

Beneficial effects of Aucubin on restoration of rabbits with cartilage defect.

Osteochondral grafts are suitable materials for repair of articular cartilage defect and plastic and reconstructive surgery. In our study, osteochondral allografts from rabbits were preserved in vitro for 28days, and chondrocyte death, degradation of collagen and proteoglycan, morphological alterations, and inflammatory reaction were observed in the grafts. Supplementing of Aucubin with 10 or 20μM in the preservation solution inhibited chondrocyte death, matrix degradation, pathological alterations and inflammation in allografts preserved in vitro, compared with that preserved in standard preservation solution. In addition, after transplantation of 20μM Aucubin-treated allografts, the osteochondral repair and regeneration of rabbits with knee joint defect were accelerated. In conclusion, Aucubin was beneficial for maintaining chondrocyte viability and normal morphology, and inhibiting inflammatory occurrence in rabbit osteochondral grafts preserved in vitro, and facilitated osteochondral repair and regeneration of rabbits with knee defect. These findings might provide novel insights for preservation of grafts for clinical articular cartilage repair and plastic surgery.

Study on ultrasonic regulation of the welding performance and defects of 7A52 aluminum alloy plate

The welding performance and defects of thick aluminum alloy plates with medium and high strength are always a hot research topic. In this study, ultrasonic technology was used to regulate the properties and defects of welded joints of a 7A52 aluminum alloy plate during double-sided welding, and these welded joints were compared with conventional welded joints. X rays were used to macroscopically detect the defects of welded joints. An optical microscope was used to analyze the grain structure and microdefects in each zone of welded joints. The tensile and impact tests were carried out on the joints. The fracture morphology of tensile and impact specimens was observed using a scanning electron microscope, and the defects and slag inclusions were analyzed by energy dispersive spectroscopy. In the process of ultrasonic welding, the crystallization process of the molten metal pool was changed, and the solidification and heat transfer environment under ultrasonic influence directly led to the change in the properties and defects of welded joints. The experimental results show that the 7A52 aluminum alloy joints can produce deep penetration and very few macroscopic defects after ultrasonic adjustment. Ultrasonic waves can refine the grains in the weld zone, heat-affected zone, and fusion zone and reduce the microdefects in each zone. The tensile and impact properties of ultrasonic welds have been improved by 84% and 87%, respectively. Therefore, ultrasonic waves can regulate the welding performance and defects of 7A52 aluminum alloy plates and other aluminum alloy plates with a similar structural composition. This study provides guidance for the selection of a double-sided welding method with low cost, high efficiency, and good joint performance for aluminum alloy plates.

An efficient solder joint defects method for 3D point clouds with double-flow region attention network

In electronics mass-production, image-based methods are often used to detect the solder joint defects for achieving high-quality assurance with low labor costs. Recently, deep learning in 3D point clouds has shown an effective form of characterization for 3D objects. However, existing work rarely involves defect detection for PCBs based on 3D point clouds. In this paper, we propose a novel neural network named double-flow region attention network (DoubRAN) to detect defects of solder joints with 3D point clouds. On the one hand, a binocular lidar system is designed to efficiently capture 3D point clouds of solder joints. On the other hand, a fine-grained method named region attention network (RAN) is designed to detect defects, which attends on the region of interest directly by backpropagation without bounding box annotation. To evaluate the performance of our proposed network, we conduct extensive experiments on a unique dataset built by ourselves. The experimental results show that the region of interest extracted by RAN is consistent with the basis for human evaluation of solder joint quality. Besides, the defect detection results of DoubRAN meet factory requirements.

Consequences of excessive deformation of structural elements in precast buildings

The work concerns the phenomenon of damage to internal partition walls in typical prefabricated residential buildings. As a construction system, large-panel buildings were very popular all over Europe at the end of the 20th century. Defects in structural members or layer joints in facade wall panels have been investigated many times. The neglected aspect of the operation of large-panel buildings are the consequences of excessive deformation of structural elements progressing over time, e.g., deflections of prefabricated floor slabs.The safety of building residents is determined not only by the fulfillment of the limit states conditions by basic structural elements, e.g. external walls or floor slabs. Failures can also occur as a result of damage to partition walls. Initially rigid floor slabs remain supported only at the edges of the structural walls, while in the middle zones they are deflected. Partition walls, made of various materials, are subjected to shear stress in addition to compression. This can result in cracks and even destruction of the wall structure.The problem presented for discussion was confirmed by the case of a real failure of partition walls in a building operated for more than thirty years. To find explanation and reasons of such a phenomenon, numerical calculations were carried out for partition walls and for prefabricated floor slabs that are under and above the analyzed wall. In the case of partition walls, the effort of the wall material was considered in terms of exceeding the ultimate limit state in the tensile zones. For the floor slabs the deflection values were determined. The implemented concept of an effective reconstruction of the wall structure has been also described.

Study on Properties of High-Vanadium Full-Locked Cable with Alloy Coating with Defects

The Zn-5%Al-rare earth alloy coating has been used in High-Vanadium Full-Locked Cable (HVFLC) that is made in China. This application has shown excellent protective performance. However, during practical use, the coating may appear to be deteriorated in various degrees, which may further worsen the corrosion resistance and mechanical properties of the cable. This paper focuses on High-Vanadium Full-Locked Cable (HVFLC). Firstly, different types of prefabricated defect treatments have been applied into the wires of the cable, followed by corrosion paste accelerated corrosion test and mechanical tensile properties test. The aim of this act is to figure out the effects on the corrosion resistance and mechanical properties of the wire due to different types of defects in alloy plating. The results show that the corrosion resistance of the wires has been greatly affected because of the solder joint defects. Furthermore, the tensile strength of the wire indicates a drop of about 40%. This research makes up the gap in the related fields in China. In addition, basic data has been provided for the development of the HVFLC in China.

MECHANICAL PROPERTIES OF REPAIR WELDING HIGH YIELD STRENGTH STRUCTURAL STEEL S690Q

Repeated welding caused by welding defects in the weld joint will result in changes in the mechanical properties of the weld joint, especially in the Heat Affected Zone (HAZ). Significant changes will occur when welding on steel materials that have undergone special treatment during the manufacturing process, such as quenched and tempered S690Q steel. S690Q steel is a structural steel with high yield strength with quenched and tempered conditions. The research was conducted by doing repeated welding as a simulation of the repair process using the GMAW process. Macro observations as well as tensile, bending, hardness, toughness tests were carried out on cross sections of welded joints. From the results of all the tests carried out the results meet the requirements of the BS EN ISO 15614-1 standard, but the results of the hardness test can identify significant changes in mechanical properties in the HAZ, especially in the bottom or root pass and hot pass areas. The average hardness value decreased from 334.07 HV at the top (face) to 209.55 HV and 198.88 HV at the bottom (hot pass and root pass) on the left side of the HAZ. While on the right side of the HAZ, the hardness value is 337.40 HV to 254.34 HV and 208.64 HV.&#x0D; Keywords: HAZ, S690Q, Structural Steel, Quenched and Tempered Steel

Hydrogel-based autologous chondrocyte implantation leads to subjective improvement levels comparable to scaffold based autologous chondrocyte implantation

PurposeScaffold-based autologous chondrocyte implantation is a well-established treatment for cartilage defects in the knee joint. Hydrogel-based autologous chondrocyte implantation using an in situ polymerizable biomaterial is a relatively new treatment option for arthroscopic cartilage defects. It is therefore important to determine if there are significant differences in the outcomes. The aim of this study is to compare the outcomes (using subjective parameters) of hydrogel-based autologous chondrocyte implantation (NOVOCART® Inject) with the outcomes of scaffold based autologous chondrocyte Implantation (NOVOCART® 3D) using biphasic collagen scaffold.MethodsThe data of 50 patients, which were paired with 25 patients in each treatment group, was analyzed. The main parameters used for matching were gender, number of defects and localization. Both groups were compared based on Visual Analogue Scale (VAS) and subjective IKDC scores, both of which were examined pre-operatively and after 6, 12 and 24 months.ResultsSignificant benefits in both VAS and IKDC scores after 2 years of follow-up in both groups were found. Comparing the groups, the results showed that in the hydrogel-based autologous chondrocyte implantation group, significant changes in IKDC scores are measurable after 6 months, while it takes 12 months until they are seen in the scaffold based autologous chondrocyte group.ConclusionHydrogel-based autologous chondrocyte and scaffold based autologous chondrocyte show comparable improvements and significant benefits to the patients’ subjective well-being after a 2-year-follow-up.Level of evidenceIII.

Empfehlungen der AG Klinische Geweberegeneration zur Behandlung von Knorpelschäden am Kniegelenk.

The Working Group of the German Orthopedic and Trauma Society (DGOU) on Tissue Regeneration has published recommendations on the indication of different surgical approaches for treatment of full-thickness cartilage defects in the knee joint in 2004, 2013 and 2016. Based upon new scientific knowledge and new developments, this recommendation is an update based upon the best clinical evidence available. In addition to prospective randomised controlled clinical trials, this also includes studies with a lower level of evidence. In the absence of evidence, the decision is based on a consensus process within the members of the working group.The principle of making decision dependent on defect size has not been changed in the new recommendation either. The indication for arthroscopic microfracturing has been reduced up to a defect size of 2cm2 maximum, while autologous chondrocyte implantation is the method of choice for larger cartilage defects. Additionally, matrix-augmented bone marrow stimulation (mBMS) has been included in the recommendation for defects ranging from 1 to 4.5cm2. For the treatment of smaller osteochondral defects, in addition to osteochondral transplantation (OCT), mBMS is also recommended. For larger defects, matrix-augmented autologous chondrocyte implantation (mACI/mACT) in combination with augmentation of the subchondral bone is recommended.

Survey on Fatigue Life Prediction of BGA Solder Joints

With the development of science and technology, consumers’ requirements for various electronic devices present a trend of more diverse functions and thinner bodies. This makes integrated circuits mounted in electronic products and their packaging more vital to satisfying the above requirements. Ball grid array (BGA) packaging is widely used in the field of microelectronic manufacturing industries due to its multiple I/O volumes and excellent electric characteristics. However, due to environmental loads such as vibration and impact during its production and application, defects inevitably emerge in BGA solder joint defects, which will lead to the failure of electronic products. This article summarizes the state-of-the-art research on the factors, analysis methods, and models for the fatigue failure of BGA chips. After rigorous discussions concerning this research, some theoretical suggestions are provided for BGA packaging in reliability analysis and the establishment of evaluation standards.

Monitoring thermal defects in rail and rail joints using piezo impedance-based structural health monitoring (PISHM)

Rail track derailment has been proven to be the cause of most of the rail accidents in recent years. High-temperature strains in railways caused by rail traction and thermal variation are the main causes of derailment, which lead to buckling. The likelihood of passenger deaths and maintenance costs will be reduced if thermal strains and failure in rails are detected early. This research attempts to provide a preventative strategy for detecting thermal strains and deformation caused by temperature fluctuations at railways. Using the electromechanical impedance (EMI) technique, piezoelectric sensors were used to acquire piezo coupled structural signatures for lab-sized rail samples, i.e. plain rail and rail joints, for gradual temperature escalation and repeat heat cycle. The experimental conductance signatures were obtained for the incremental rise in temperature (30–80 °C) in ambient conditions, and repetitive thermal cycles. To better diagnose structural problems induced only by the effect of heat on the host structure, thermal compensation is proposed. The piezo–coupled signatures for thermal changes in rail and rail junctions (weld and bolt) were found to be particularly effective in detecting incipient structural alterations for both steady and cyclic temperature variations. Statistical damage index was used to quantify the damage for all types of rail-joint bar caused due to temperature variation. Overall, this study has paved an experimental technique that can be used to detect early damage in rail and rail joints due to thermal loading.

Investigation of the Nature of Damage to Welded Flexible Compensating Elements Made of Austenitic Stainless Steels

Welded flexible compensating elements made of austenitic stainless steels, such as metal hoses and bellows expansion joints, operate in a complex stress state; therefore, almost all corrosion damage of these products occurs in a stressed state. In addition, in welded joints, defects are possible associated with elastic-plastic deformations and stresses arising in the manufacturing process. Paper considers the defects of welded joints of multilayer bellows expansion joints made of stainless steels AISI 304 and AISI 316 types. The influence of the parameters of the argon tungsten electrode welding mode, with or without filler wire, on the mechanical characteristics of welded joints was studied. Mechanical tests of samples of welded joints were carried out on a tensile testing machine. The optimal range of variation of the parameters of the welding mode has been established, in which the plastic characteristics of the welded joints have maximum values. A metallographic study of the microstructure of welded joints of metal hoses and bellows expansion joints was carried out. The influence of the content of nonmetallic inclusions in the material of products on the conditions of melting and crystallization of the weld pool, contributing to the appearance of pores and hot cracks in the metal of the weld and the heat affected zone, has been established. To reduce the influence of the content of non-metallic inclusions in the weld metal and the heat-affected zone on the conditions of melting and crystallization of the weld pool, it is recommended to carry out preliminary heat treatment of the austenitic steel strip.

Application of Biological Composite Materials in the Regeneration of Subchondral Defects and Articular Cartilage in a Synovial Joint: An Experimental Model.

Objective: Since the benefits of Nano-material usage have been well documented in orthopedic surgery, this study was conducted to explore the effect of polyvinyl alcohol/nano-hydroxyapatite/polyamide 66 (PVA/n-HA/P66) on repairing of traumatic cartilage defects in rabbit knee joint. Methods: New Zealand white rabbits were used to make a rabbit knee traumatic cartilage defect animal model. All rabbits were randomly located in three groups. Group-A (PVA/n-HA+PA66 implanted in cartilage defects); Group-B (HA nanospheres implanted in cartilage defects)/Gelatin sponge composite scaffold); Group-C (only cartilage defect without implant). The repairment of articular cartilage defects and the general observation were studied by using pathological staining and gene expression of collagen using RT-PCR after 12 weeks. Results: After 12 weeks, we observed a small amount of fibrous tissue growth in group C without soft cell filling. The repaired tissue in group B was stained with immunohistochemical and toluidine blue staining for collagen and type II collagen is positive, but chondrocyte structure is more visible. The relative mRNA expression of type II collagen was higher in group B in comparison to other groups. The results of the Wakitani score were 5.50±2.59 for group A, 8.83±2.79 for group B, 11.50±1.05 for group C. Results showed no significant difference between group B and C; however, significant differences were found in the scoring results between groups A and B, and between-group A and C. Conclusion: This study showed the high effectiveness of PVA/n-HA+PA66 in the treatment of cartilage defects through increasing the expression of type II collagen.

Об использовании пазов для моделирования трещин при ультразвуковой дефектоскопии

An analysis of the possibility of a rigorous theoretical solution of the three-dimensional problem of elastic wave scattering at the tip of a vertical crack in a welded joint was carried out. It was shown that in the general case of ultrasound scattering on a flat target, the three-dimensional problem can be reduced to a two-dimensional one. On this basis, for an arbitrary direction of sounding a crack in a weld, the dependence assessment of the signal from the crack tip on the direction to the receiver was made. It is noted that the wave size of the crack tip is much smaller than the wave size of the notches tip that can be machined to simulate defects in welded joints. As a result, it is shown that the nature of the scattering of elastic waves at the tip of the crack differs from the nature of scattering on the notches, including in cases where the opening of the notches is minimal based on the possibility of their manufacture. The results of an experimental verification of the obtained theoretical estimates on steel and aluminum samples were presented. It was shown that, in contrast to the tip of the cracks, at the tips of the notches, even with their minimal openings, conditions are created for the formation of a scattered field by the type of specular reflection from a volumetric cavity - a side cylindrical reflector.