Fracture Characteristics Research Articles

Effect of Process Parameters on the Mechanical Properties of Simultaneous Double-Sided Friction Stir Welding Joints

Currently, conventional single-sided friction stir welding is primarily suitable for joining thin plate aluminum alloys, and its application to thick plates is still challenging in terms of welding efficiency and joint mechanical properties. Simultaneous double-sided friction stir welding (SDS-FSW) is a high-efficiency joining technique specifically developed for welding thick plates. However, there is little research on the influence of SDS-FSW process parameters on the joint mechanical properties. In this study, a 12 mm thick AA6061-T6 aluminum alloy and dual robot welding equipment are used to conduct SDS-FSW experiments exploring the influence of rotational speed ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega$$\\end{document} and welding speed v on the mechanical properties and microstructure. The results show that when the welding parameters are ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega$$\\end{document} = 800 r/min and v = 60–80 mm/min, smooth and defect-free thick plate aluminum alloy SDS-FSW joints can be obtained, and the macroscopic morphology of the joints is distributed in a “dumbbell” shape. The grain size in the weld nugget zone increases with increasing welding heat input. The microhardness distribution in the joint displays a “W” shape, and the hardness value of the weld nugget zone can reach 67% to 86% of that of the base metal (BM). The junction between the thermo-mechanically affected zone and the heat affected zone is the weakest region of the joint, with the lowest hardness being approximately 51% of that of the BM. When the welding parameters are ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega$$\\end{document} = 800 r/min and v = 140 mm/min, the SDS-FSW joint has the highest tensile strength, reaching 78.43% of the BM strength and exhibiting ductile fracture characteristics. This research indicates that acceptable weld strength in thick aluminum alloys can be achieved via the SDS-FSW joining mechanism, highlighting its significant potential for industrial applications.

Relationship between the microstructural energy release rate of cortical bone and age under compression condition

Most studies evaluated the energy release rate of cortical bone macrostructure under Mode I, Mode II, and mixed Mode I-II loading conditions. However, testing the macrostructural energy release rate requires an initial crack and recording the applied load and the corresponding crack length in real-time, which may introduce measurement errors and differences with the actual fracture scenarios. To further understand how the energy release rate contributed to the cortical bone fracture characteristics, this study predicted the microstructural energy release rate of cortical bone and then investigated its age-related varitions. The microstructural energy release rate of femoral cortical bone in rats from different ages was back-calculated by fitting the experimental and simulated load–displacement curves under compression load. The trends in the microstructural energy release rate were revealed, and the underlying reasons for the age-related changes were investigated by integrating the discussion on the cortical bone mechanical parameters at various levels obtained from the previous experiment. The predicted microstructural energy release rate of femoral cortical bone in the rats from 1, 3, 5, 7, 9, 11, and 15 months of age were in the range of 0.08–0.12, 0.12–0.14, 0.15–0.19, 0.25–0.28, 0.23–0.25, 0.19–0.22, and 0.13–0.16 N/mm, respectively. The statistical analyses showed the significant differences in the microstructural energy release rate at different ages. The results indicated an increasing trend followed by a decrease from 1 to 15 months of age, and the correlations between microstructural energy release rate and age were significant. The age-related variations in the microstructural energy release rate may be linked to the changes in the microarchitecture, and the fracture load is influenced by the micro-level mechanical parameters. Notably, the age-related trends in microarchitecture and energy release rate were similar. These findings were valuable for understanding the mechanism underlying the weakening mechanical properties of cortical bone microstructure with age from an energy perspective.

A retrospective epidemiological analysis of maxillofacial fractures at a tertiary referral hospital in istanbul: a seven-year study of 1,757 patients

BackgroundThe aim of the study was to evaluate the etiology, incidence, demographics, and characteristics of maxillofacial fractures treated at a university hospital over a seven-year period.MethodsWe performed a retrospective analysis of 1,757 patients with maxillofacial fractures who were referred to our department between May 2012 and March 2019. The patients’ demographic and clinical characteristics were noted, as well as the fracture type, location, and etiology. The treatment modalities were also analyzed.ResultsA total of 2,173 maxillofacial fractures were seen in 1,757 patients. The male to female ratio was 3.9:1, and the mean patient age was 31.89 ± 17.70 years (range: 0–95 years). Maxillofacial injuries were most prevalent in the 19–28 years age group (23.9% of cases), with a general increase in injuries observed between 2013 and 2018 across all age groups. The most common etiological factor was assault (29.1%), followed by falls (26%). In male patients, assault was reported as the main cause, while in female patients, falls were identified as the main cause. The nasal bone was the most common site of fracture, followed by the maxilla. The average time from admission to surgery was 2.8 days, with local anesthesia being the most frequent surgical intervention. The average time from admission to surgery was 2.8 ± 2.5 days (range: 0–20 days), with surgeries performed under local anesthesia being more frequent than those carried out under general anesthesia. Among the surgical interventions, the most common general anesthesia technique for fracture reduction was open reduction and internal fixation with plates and screws. Plate exposure, wound-site infection, and temporomandibular joint ankylosis were the major complications encountered in the study population.ConclusionThe study reveals significant variability in maxillofacial fractures based on gender, age, and etiology. Assault emerged as the leading cause of these fractures, followed by falls and road traffic accidents. Men were affected by maxillofacial trauma four times more often than women, with the highest incidence occurring in the 19–28 years age group. Nasal fractures were the most frequently observed (78.7%), while condylar-subcondylar process fractures were the most common type of mandibular fracture. Given these findings, a targeted, lifelong prevention strategy focused on high-risk groups could significantly reduce the burden of maxillofacial trauma.

Progress of fracture mapping technology based on CT three-dimensional reconstruction

Fracture Mapping is a new technology developed in recent years. This technology visually representing the morphology of fractures by overlaying fracture lines from multiple fracture models onto a standard model through three-dimensional reconstruction. Fracture mapping has been widely used in acetabular fracture, proximal humerus fractures, Pilon fracture, tibial plateau fractures, and so on. This technology provides a new research method for the diagnosis, classification, treatment selection, internal fixation design, and statistical analysis of common fracture sites. In addition, the fracture map can also provide a theoretical basis for the establishment of a biomechanical standardized fracture model. Herein, we reviewed various methods and the most advanced techniques for fracture mapping, and to discuss the issues existing in fracture mapping techniques, which will help in designing future studies that are closer to the ideal. Moreover, we outlined the fracture morphology features of fractures in various parts of the body, and discuss the implications of these fracture mapping studies for fracture treatment, thereby providing reference for research and clinical decision-making on bone and joint injuries to improve patient prognosis.

Asymmetric deformation and failure behavior of roadway subjected to different principal stress based on biaxial tests

The magnitude and direction of stress will affect the failure of roadway. The impact of stress magnitude and direction on roadway failure was investigated using a rock failure system equipped with true triaxial loading, acoustic emission (AE), and digital image correlation (DIC) technologies. The system allowed for the simulation of rock sample failures under various three-dimensional stress conditions, while real-time monitoring was conducted using a high-precision microseismic system. By prefabricating rectangular holes at different angles in sandstone specimens, roadways under different stress effects in engineering can be simulated. Biaxial loading tests were then performed on these prefabricated sandstone cube specimens to observe external fracture characteristics and internal fracture information using acoustic emission equipment. The peak strength of samples with holes is approximately 38–56% of that of intact samples. In the early and middle loading stages, the strain on the surface is on the order of 10-3. In the later loading stage, the strain on the surface is on the order of 10-2. The findings indicate that roadway failure primarily involves local particle ejection, fragment spalling, large-scale particle ejection, plate crack buckling, and eventual failure. The ultimate failure mode varies based on stress deflection angles: with no included angle, the roadway exhibits a ’V’ shaped failure zone on both sides, predominantly experiencing tensile failure. At included angles of 30°, 45°, and 60° between stress and roadway axis, the roadway displays a “—” failure pattern along the diagonal, characterized by a combination of tension and shear failure. The extension angle of the“—” failure zone varies depending on the stress deflection angle. At a 90° included angle, the roadway shows a ’V’ shaped failure in the roof and floor, primarily undergoing tensile failure. Real-time monitoring of the strain field evolution around the roadway during failure using DIC method revealed valuable insights. AE events at different deflection angles reflect the progression of micro cracks in the specimen, showing a strong correlation with macro failure. The research outcomes elucidate the mechanisms behind various forms of roadway failure induced by stress deflection and shed light on the failure mechanism at different stress deflection angles.

Heat treatment effect on the carbides in T-15 and M-4 steels

ABSTRACT In the present work, the effect of heat treatment on the microstructure and mechanical properties of T-15 and M-4 high-speed steels was investigated. These steels were produced by powder metallurgy. Due to their frictional wear resistance properties, T-15 and M-4 high-speed steels are widely used in the cutting tool manufacture of the metalworking industry. A heat treatment was applied to both steels, heating them to 1250°C, then air quenching and, finally tempering at 550°C for 2 h, 3 times (triple tempering at 550°C). Steels were characterized by hardness test, metallographic analysis, tensile strength test, and fracture analysis after the heat treatment. Results were compared and related to the metallurgical microstructure, mainly to the distribution of carbides, and also to fracture type and characteristics. Test results and chemical analysis showed important differences between T-15 and M-4 steels.

FEM, DEM and FDEM applications on impact fracture of glass and laminated glass – a review

Structural glass components are prevalently used in engineering. Due to the brittle nature, glass or laminated glass may fracture during an impact action, and the subsequent flying fragments may spread over a wide range, resulting in human injuries and asset losses. In this article, the authors aimed at providing a comprehensive review concerning the numerical applications on the impact fracture of glass and laminated glass, giving emphasis to the literatures published in the last two decades. Relevant numerical applications employing the finite element method (including element deletion method, extended finite element method and some other continuum-based approaches), discrete element method and combined finite-discrete element method were reviewed in-depth, and features of the simulations were summarised. Discussions on the impact fracture characteristics from different computational approaches were performed. Insights into the accuracy, efficiency, ease of implementation and range of applicability were also provided. This review is meant for the rapid and beneficial understanding towards the impact fracture mechanism of glass and laminated glass.

Tibial Insufficiency Fracture with Characteristics of an Atypical Fracture: A Rare Case and Literature Review

Background and Objectives: Osteoporosis is becoming more prevalent with the rise in the aging population, leading to the increased use of bisphosphonates for treatment. While these medications are effective in preventing osteoporotic fractures, long-term use has been associated with atypical insufficiency fractures, primarily in the femur. However, atypical fractures in other weight-bearing bones, such as the tibia, have rarely been reported. This study aims to present a case of an atypical insufficiency fracture of the tibia in an elderly female who has been on long-term bisphosphonate therapy and to review treatment outcomes within the context of the current literature. Patient concerns: A 76-year-old female presented with pain in the proximal right tibia, developing two months prior without trauma. She had been receiving long-term bisphosphonate therapy for osteoporosis, initially taking sodium risedronate orally for 4 years, followed by intravenous ibandronate for 10 years. Physical examination revealed localized tenderness, and radiographs showed cortical thickening and a horizontal fracture line in the proximal right tibia. MRI confirmed these findings, along with surrounding edema. The laboratory results were mostly normal, but the bone formation marker osteocalcin was significantly reduced. The patient had a history of insufficiency fractures in the ipsilateral tibia and contralateral femur, previously treated conservatively with teriparatide. A similar conservative approach was attempted but failed, leading to surgical intervention with intramedullary nailing and supplementary plating. At the 8-month follow-up, the patient showed successful fracture union and resolution of symptoms. Conclusion: Long-term use of bisphosphonates, though effective for osteoporosis, can lead to atypical insufficiency fractures, primarily in the femur but also occasionally in the tibia. Clinicians should consider this possibility when patients present with pain in weight-bearing bones without a history of trauma. Prompt diagnosis through thorough history-taking, physical examination, and appropriate imaging is essential to ensure timely management.

WCAY object detection of fractures for X-ray images of multiple sites

The WCAY (weighted channel attention YOLO) model, which is meticulously crafted to identify fracture features across diverse X-ray image sites, is presented herein. This model integrates novel core operators and an innovative attention mechanism to enhance its efficacy. Initially, leveraging the benefits of dynamic snake convolution (DSConv), which is adept at capturing elongated tubular structural features, we introduce the DSC-C2f module to augment the model’s fracture detection performance by replacing a portion of C2f. Subsequently, we integrate the newly proposed weighted channel attention (WCA) mechanism into the architecture to bolster feature fusion and improve fracture detection across various sites. Comparative experiments were conducted, to evaluate the performances of several attention mechanisms. These enhancement strategies were validated through experimentation on public X-ray image datasets (FracAtlas and GRAZPEDWRI-DX). Multiple experimental comparisons substantiated the model’s efficacy, demonstrating its superior accuracy and real-time detection capabilities. According to the experimental findings, on the FracAtlas dataset, our WCAY model exhibits a notable 8.8% improvement in mean average precision (mAP) over the original model. On the GRAZPEDWRI-DX dataset, the mAP reaches 64.4%, with a detection accuracy of 93.9% for the “fracture” category alone. The proposed model represents a substantial improvement over the original algorithm compared to other state-of-the-art object detection models. The code is publicly available at https://github.com/cccp421/Fracture-Detection-WCAY .

Fracture behavior of NiNb and NiNbP bulk metallic glasses

While it is known that phosphorous additions enhance the hardness, strength, and glass forming ability of NiNb(P) bulk metallic glasses, nothing is known about the trade-offs regarding the fracture characteristics. The fracture toughness and bending deformation behavior of Ni62Nb38 and Ni59.2Nb38.8P2 BMGs were studied, both of which have been reported to have very high compressive yield strength near 3GPa. The binary NiNb BMG exhibited ~4% plastic bending strain and a precracked fracture toughness of KQ = 50MPa√m which gives an excellent combination of strength and toughness relative to other engineering materials. With the addition of 2at.% phosphorus, the glass forming ability was maximized, but the BMG was hardened and embrittled, fatigue precracking was no longer possible, and micronotched toughness values, which should overestimate the precracked fracture toughness, were in the range of KQ = 19 − 26MPa√m. Additionally, a progressive hardening and bending embrittlement was observed for intermediate P additions of 1 and 1.5at.% phosphorus. Transmission electron microscopy revealed larger medium range order clusters in the relatively softer NiNb BMG which were thought to contribute to easier shear transformations and plastic deformation by shear banding.

Fracture and fractal characteristics of high-temperature granite under confined space water jet impact

In the application of jet assisted deep drilling technology, the fracture mode and rock fragment characteristics of high-temperature rock in the confined space of jet drilling are not yet clear. We analyzed the fragmentation and debris distribution of high-temperature granite under confined space jet action using 3D reconstruction technology and statistical fractal theory to examine their fragmentation patterns and fractal characteristics. The results show that high-temperature rocks exhibit obvious thermal fracturing characteristics under the impact of confined water jet, and as the rock temperature increases, vertical compression shear cracks connect with radial tensile cracks. The maximum damage area is located near the bottom of the confined hole, and the distribution of cracks is more complex. As the degree of jet confinement decreases, the rock cracking form changes from radial tensile cracking to vertical compression shear cracking. As the rock temperature increases and the confined space size decreases, the total mass and large debris mass percentages of rock debris increase. The particle size distribution of rock debris follows an Rosin-Rammler (R-R) distribution and has obvious fractal characteristics. The fracture and fragmentation of high-temperature rocks under confined water jet impact are mainly caused by the combination of jet impact stress waves and thermal stress. The temperature difference of rocks affects the heat transfer between jet and rock, and the confined space size directly affects the heat transfer efficiency between jet and rock, which is manifested in different numbers of fracture cracks, internal damage area, and rock debris size distribution. These findings can provide a theoretical and parameter optimization basis for jet-assisted deep reservoir drilling applications.

Dynamic deformation and fracture of brass: Experiments and dislocation-based model

In this work, we perform a comprehensive study of the dynamic deformation and fracture of brass, including Taylor tests with classical and profiled cylinders and ball throwing experiments reaching the strain rates of about (0.1−1)/μs, as well as atomistic and continuum-level numerical modeling. Molecular dynamics (MD) simulations are used to construct the equation of state (EOS) of brass and to study its fracture characteristics at shear deformation under negative pressure. An original model of fracture under combined tensile-shear loading is formulated, which takes into account both the accumulation of empty volume in the process of lattice loosening due to the lattice defect production in the course of plastic deformation and further mechanical growth of voids controlled by the dislocation plasticity. This atomic-scale model is transmitted to the macroscopic experiment-scale level and embedded into 3D dislocation plasticity model to describe the dynamic deformation and fracture of brass using the numerical scheme of smoothed particle hydrodynamics (SPH). A part of experimental data is used to find the optimal parameters of the dislocation plasticity model by means of the Bayesian global optimization method accelerated with the help of artificial-neural-network (ANN)-based emulator of the 3D model. Another part of experimental data is used to fit the fracture model parameter. The remaining experimental data, which are not used in the parameterization, are applied to verify the parameterized model. The developed physical-based model provides correct and meaningful description of the dynamic deformation and fracture of brass, while the developed formalized approach to its parameterization opens a way to wider use of this type of models in the engineering applications, including studies on dynamic performance and high-speed processing technologies.

Detection, classification, and characterization of proximal humerus fractures on plain radiographs.

The purpose of this study was to develop a convolutional neural network (CNN) for fracture detection, classification, and identification of greater tuberosity displacement ≥ 1 cm, neck-shaft angle (NSA) ≤ 100°, shaft translation, and articular fracture involvement, on plain radiographs. The CNN was trained and tested on radiographs sourced from 11 hospitals in Australia and externally validated on radiographs from the Netherlands. Each radiograph was paired with corresponding CT scans to serve as the reference standard based on dual independent evaluation by trained researchers and attending orthopaedic surgeons. Presence of a fracture, classification (non- to minimally displaced; two-part, multipart, and glenohumeral dislocation), and four characteristics were determined on 2D and 3D CT scans and subsequently allocated to each series of radiographs. Fracture characteristics included greater tuberosity displacement ≥ 1 cm, NSA ≤ 100°, shaft translation (0% to < 75%, 75% to 95%, > 95%), and the extent of articular involvement (0% to < 15%, 15% to 35%, or > 35%). For detection and classification, the algorithm was trained on 1,709 radiographs (n = 803), tested on 567 radiographs (n = 244), and subsequently externally validated on 535 radiographs (n = 227). For characterization, healthy shoulders and glenohumeral dislocation were excluded. The overall accuracy for fracture detection was 94% (area under the receiver operating characteristic curve (AUC) = 0.98) and for classification 78% (AUC 0.68 to 0.93). Accuracy to detect greater tuberosity fracture displacement ≥ 1 cm was 35.0% (AUC 0.57). The CNN did not recognize NSAs ≤ 100° (AUC 0.42), nor fractures with ≥ 75% shaft translation (AUC 0.51 to 0.53), or with ≥ 15% articular involvement (AUC 0.48 to 0.49). For all objectives, the model's performance on the external dataset showed similar accuracy levels. CNNs proficiently rule out proximal humerus fractures on plain radiographs. Despite rigorous training methodology based on CT imaging with multi-rater consensus to serve as the reference standard, artificial intelligence-driven classification is insufficient for clinical implementation. The CNN exhibited poor diagnostic ability to detect greater tuberosity displacement ≥ 1 cm and failed to identify NSAs ≤ 100°, shaft translations, or articular fractures.

High cycle fatigue properties of Ti-48Al-2Cr-2Nb alloy additively manufactured via twin-wire directed energy deposition-arc

Recently, additive manufacturing for titanium aluminide has received sustained attention. Considering the extensive applications on low pressure turbine blades in aerospace field, dynamic mechanical properties of titanium aluminide, especially the fatigue properties, are of great importance. In present work, fatigue test at ambient temperature was conducted for the first time on twin-wire directed energy deposition-arc (TW-DED-arc) fabricated Ti-48Al-2Cr-2Nb alloy with equiaxed lamellar colonies. More detailed researches on fatigue fracture characteristics and deformation modes are also investigated. The experiment results indicate that TW-DED-arc fabricated Ti-48Al-2Cr-2Nb alloy exhibits flat S–N behavior with a good resistance to fatigue. Fatigue life fluctuates widely at same stress level, but such fluctuations gradually weaken as stress decreases. Furthermore, γ/α2 interface and lamellar colony boundary as well as special microstructures of as-fabricated Ti-48Al-2Cr-2Nb alloy are weak areas during fatigue process, which easily become crack nucleation sites. As stress level decreases, deformation mode of as-fabricated Ti-48Al-2Cr-2Nb alloy translates from twinning and dislocation slip to predominantly dislocation slip. In general, these findings provide an important reference for engineering applications of titanium aluminide.

Dissimilar unbeveled aluminum to steel butt joint achieved by laser-arc hybrid welding-brazing

In this study, unbeveled butt joints of 2 mm thick steel and aluminum plates were welded using a laser-arc hybrid process. The influence of welding speed and wire feed speed on joint weld formation, microstructures, and mechanical properties were investigated. The results indicate that using a laser-arc hybrid heat source enables good weld formation of steel/aluminum dissimilar metals without groove preparation, even under high welding speed conditions. The steel side interface formed Fe₂(Al,Si)₅ near the steel and Fe(Al,Si)₃ near the aluminum. As the welding heat input decreased, the thickness of the intermetallic compounds gradually reduced. With an increase in welding speed or wire feed speed, the tensile strength of the joint first increased and then decreased, reaching a maximum of 104.47 MPa. Cracks propagated rapidly along the intermetallic compound region, resulting in brittle fracture characteristics. The three-point bending test showed a maximum longitudinal bending angle of 53.82° and a maximum transverse bending angle of 36.54°.

The hysteresis loop on the near-threshold fatigue crack growth curves generated by stepped load reduction and constant-amplitude loading methods in a Ni-based superalloy

Fatigue crack growth (FCG) tests were conducted on compact tension specimens made of a Ni-based superalloy to investigate the near-threshold FCG behaviors using both the stepped load reduction method (LRM) and the constant-amplitude loading method (CALM) at three stress ratios (R = 0.05, 0.5 and 0.7) under ambient condition. It is found that after the FCG threshold being approached by the LRM, a remarkable hysteresis plateau occurs on the subsequent FCG curve generated by the CALM for R ≤ 0.5, resulting a hysteresis loop on the near-threshold region, but the situation becomes complicated at R = 0.7. In the appearance of hysteresis plateau, the FCG life to fracture can be over 107 cycles longer than that without hysteresis plateau. For FCG rate faster than 10−8 m/cycle, the fractography is dominated by transgranular feature which is insensitive to the microstructure of the alloy. In the hysteresis plateau region where FCG rate is lower than 10−9 m/cycle, fractography shows a wide optical dark zone where microstructure-sensitive crystallographic facet feature dominates, while when no hysteresis at R = 0.7, the optical dark zone is too narrow for the fracture feature transition so that crystallographic facet, transgranular as well as mosaic features can be observed simultaneously. As FCG in the hysteresis plateau under the CALM can be significantly slower than that under the stepped LRM, it is recommend that the stepped LRM should be used to generate the material basic FCG curves for fatigue life prediction of high durability structures.

Detection of clavicle fracture after martial arts training based on 3D segmentation and multi-perspective fusion

To improve the diagnosis efficiency of clavicle fractures, a Diagnosis Model of Clavicle Fracture Based on 3D Segmentation and Multi Perspective Fusion (3Ds MPF) is proposed in the experiment. By performing 3D segmentation on clavicle images, key layer images are extracted, and multi-perspective image data are fused and output to achieve accurate classification and diagnosis results. The results show that on the relevant dataset, the loss function value of the constructed model is less than 0.01, and the calculation accuracy is as high as 0.999. The average classification accuracy in actual use exceeds 90%, and it can capture the majority of fracture features in clavicle computed tomography images. The above results indicate that the model constructed by the research institute can significantly improve the judgment efficiency of computed tomography images, which helps to enhance the detection and diagnosis of clinical fracture conditions. The experimental results have helped improve the clinical diagnostic efficiency of fracture detection work.

Frequency and mechanism of injury for unintentional paediatric femoral fractures associated with consumer products over a 10-year period in the USA.

Femoral shaft fractures tend to be rare among children; however, these injuries are the most common major paediatric injuries treated by orthopaedic surgeons. The purpose of this study is to characterise the demographics and mechanisms of femoral injury associated with consumer products in the age group treated with spica casting, children 6 months to 6 years, to identify areas for injury prevention. Data from 2012 to 2021 were obtained from the National Electronic Injury Surveillance System maintained by the Consumer Products Safety Commission, documenting emergency department visits for unintentional injuries associated with consumer products. Narrative descriptions were analysed to identify common factors in the injury events such as location, products and mechanisms of action. From 2012 to 2021, the estimated incidence of femur fractures was 23.5 cases per 100 000 children with no significant difference in yearly frequency. The most common mechanism of injury was a fall with the most frequent fracture sources being bed/bunk beds (16.1%), floor (slips/falls, 9.7%) and trampolines (9.7%). Most fractures occurred at the patient's home (58.4%). The incidence of injury outside of the home and frequency of fractures involving play structures/trampolines increased with age. The incidence and demographic characteristics of paediatric femur fractures associated with consumer products have remained consistent over the past 10 years. As home was the most common location of fracture, prevention of femur fractures should focus on caregiver education around high-risk sources of fracture (bed, stairs and trampolines) and manufacturers should consider design alternatives that discourage potential misuse.

Research on accelerated thermal fatigue testing and life prediction of Al-Si alloy pistons under start-stop cycles

As one of the most critical components in the combustion chamber of diesel engines, pistons operate under high temperature and pressure conditions for extended periods, which increases the likelihood of failures such as thermal fatigue. This paper first utilizes finite element simulation to obtain the temperature and stress field distribution of an Al-Si alloy piston under actual engine conditions. The results indicate that the throat area of the piston is the most susceptible to fatigue failure. Based on this, accelerated thermal fatigue tests were conducted to study the influence of various experimental factors on piston life, as well as to analyze the weight of each factor. Results from macroscopic and microscopic analyses of cracks using a scanning electron microscope show that fatigue cracks originate at the interface between the aluminum matrix and the detached hard particles. The cracking at the piston throat exhibits clear characteristics of ductile fracture, which is the result of cumulative fatigue damage. Therefore, from the perspective of continuum damage mechanics, it is considered to characterize the equivalent stress using the average loading rate during the loading phase and the maximum axial temperature gradient, establishing an experimental life prediction model for Al-Si alloy pistons.

Fracture morphology and ossification process of the keel bone in modern laying hens based on radiographic imaging.

Keel bone fractures (KBF) are one of the most important welfare problems in commercial laying hens. Despite extensive research on the matter, its etiology remains unclear. Studying fracture characteristics in radiographic images can aid in the understanding of the disorder. The aim of the current study was to provide detailed description of fracture characteristics and explore ossification in the keel bone. In this descriptive study, repeated cross-sectional sampling was performed in one commercial laying hen flock. The flock was visited at 11 time points from 17-57 weeks of age (WOA), radiographing 30 laying hens at each visit resulting in altogether 330 unique radiographs. Fracture characteristics and the keel bone's level of ossification were assessed in each radiograph. In total, 344 fractures were recorded, of which 71.5% were complete and 28.5% were incomplete. Of the complete fractures, 82.9% were recorded as transverse, and 15.9% as oblique. One comminuted and two butterfly fractures were recorded. The caudal third of the keel was the most common area for fractures. Fracture characteristics differed between the different regions of the keel bone; all incomplete fractures in the cranial third appeared on the ventral surface of the keel, whilst the majority of incomplete fractures on the caudal third appeared on the dorsal surface. This indicates that the underlying etiology might differ between the cranial and caudal part. Folding fractures were observed in 18.6% of all the fractures, and occurred in both cranial-, and caudal third of the keel, indicating possible underlying disorders of calcium metabolism. All hens at 32 WOA and older had a fully ossified keel, based on radiographic evaluation. Displacement and soft tissue swelling are common characteristics in fractures of traumatic origin. We found a high frequency of simple fractures, without these characteristics, indicating that non-traumatic causes may be of higher importance than conventional beliefs.