Maximum Strain Research Articles

Factors associated with urinary incontinence in nulliparous female elite athletes: an exploratory, cross-sectional study using dynamic pelvic magnetic resonance imaging and questionnaire data.

Urinary incontinence (UI) is common in nulliparous female elite athletes, but underlying pathophysiology is inadequately understood. We examined urinary symptoms and associated pelvic floor anatomy and function in this population, hypothesizing that athletes with UI would exhibit pelvic floor findings seen in older incontinent women (e.g., pelvic floor descent and urethral hypermobility) and findings attributable to elite sporting such as muscle hypertrophy. We performed a cross-sectional study of NCAA Division 1 nulliparous female athletes comparing symptomatic (i.e. currently or previously experienced urinary leakage during exercise) and asymptomatic athletes. We assessed demographics, sport characteristics, relevant medical history (including Brief Eating Disorder in Athletes Questionnaire) and validated genitourinary symptom questionnaires (Lower Urinary Tract Dysfunction Network Symptom Index-29; Female Genitourinary Pain Index). Pelvic exam and dynamic MRI were used to assess the pelvic floor at rest and at maximal strain. Pelvic floor anatomic structures were evaluated and segmented by MRI. Of 29 athletes (11 asymptomatic, 18 symptomatic), demographics, sport characteristics, and pelvic exam findings were not statistically different between groups. Symptomatic athletes had significantly worse urinary symptoms (median LURN SI-29 8.5 vs. 8.0, P=0.022) and genitourinary pain (median GUPI 7 vs. 3, P=0.036), greater anterior thickness of the striated urethral sphincter muscle (median 2.5 vs. 1.8 mm, P=0.016) and puborectalis and levator ani muscles (median 10.3 vs. 8.6 mm, P=0.028), and worse disordered eating (median BEDA-Q 7.5 vs. 4.5, P=0.022). In nulliparous female elite athletes with UI, dynamic pelvic MRI identified differences in pelvic floor anatomy, which may be part of a multifactorial etiology of UI.

Stretchable Blue Phase Liquid Crystal Lasers with Optical Stability Based on Small-Strain Nonlinear 3D Asymmetric Deformation.

Blue phase liquid crystal (BPLC) lasers exhibit exceptional optical quality and tunability to external stimuli, holding significant promise for innovative developments in the field of flexible optoelectronics. However, there remain challenges for BPLC elastomer (BPLCE) lasers in maintaining good optical stability during stretching and varying temperature conditions. In this work, a stretchable laser is developed based on a well-designed BPLCE with a combination of partially and fully crosslinked networks, which can output a single-peak laser under small deformation (44.429nm lasing shift at 32% strain) and a broad-temperature range (from -20 to 100°C). The superior performance can be attributed to the nonlinear 3D asymmetric deformation exhibited by the BPI lattice during stretching, particularly at low deformation rates below 40% strain, which effectively maintains the stability of the body-centered cubic structure (with the maximum strain of this BPLCE up to 220%). Moreover, the BPLCE exhibits excellent thermal stability over a temperature range from -180 to 70°C with a stopband shift of less than ±10nm. As a proof-of-concept, the application of BPLCE laser for morphology sensing and 3D mechanical perception is demonstrated, which paves the way for potential applications of flexible optoelectronics.

Ultrasensitive Flexible Strain Sensor Based on the Synergistic Integration of Wrinkle and Microcrack Architectures for Wearable Applications

Wearable strain sensors have significant applications in important domains such as electronic skin, personalized health monitoring, and human–computer interaction. A prevailing objective in numerous research initiatives is to achieve a balance between high sensitivity and stretchability. A strain sensor that integrates a stretchable wrinkled structure with a highly sensitive microcrack sensor to address this is developed. This sensor employs wrinkled microstructures, constructed by thermally depositing a gold film onto a flexible substrate. Due to its unique microstructural design, the sensor demonstrates a maximum strain of 75% and a gauge factor reaching 6657. Additionally, the sensor exhibits outstanding mechanical stability, maintaining consistent performance through 1000 stretching–releasing cycles. The application of this wrinkle structure strain sensor in human motion tracking, physiological signal monitoring, and speech recognition is validated. These findings underscore its practical value in wearable technology and offer novel insights for the advancement of next‐generation wearable electronic devices.

Highly Conductive Ionohydrogels for Humidity Sensing

Polymeric hydrogel materials have excellent electrical conductivity and mechanical properties and will be potentially used in wearable electronic devices, soft robotics, and medical treatment. In this paper, a PAA-Fe3+-IL ionohydrogel (poly(acrylic acid)-Fe3+-ionic liquid ionohydrogel) with excellent mechanical and conductive properties is prepared by simple free radical polymerization. The presence of metal–ligand crosslinking within the ionohydrogel improves the mechanical properties of the hydrogel. When the IL content is 10 wt%, it has the maximum tensile strength and strain. When the ferric ion concentration is 0.3 mol%, the maximum tensile strength is 495.09 kPa. When the ferric ion concentration is 0.1 mol%, the maximum strain is 1151.35%. The tensile behavior of the ionohydrogels is quantitatively analyzed by the viscoelastic model. In addition, free metal ions and anions and cations in IL endowed the hydrogel with a conductivity of 1.48 S/m and a strain sensitivity of 8.04. Thus, the PAA-Fe3+-IL ionohydrogel can be successfully used as a humidity sensor due to the hydrophilic ionic liquid, which can increase the conductivity of the hydrogel by absorbing water. The physical crosslinking density inside the hydrogel is much higher than the chemical crosslinking density, which causes hydrogel dissolution in deionized water by swelling and is conducive to the recycling of the hydrogel. This is a promising material for use in intelligent wearable electronics and as a humidity sensor.

Research on restraint strategies for rearward-reclined occupants in a frontal rigid barrier crash

Autonomous driving technology has led to an increasing preference for rearward seating postures. However, current restraint systems exhibit significant shortcomings in protecting reclined occupants. In this paper, based on the existing restraint system components, various restraint strategies were configured to enhance the protection for reclined occupants. Firstly, this research developed a model of the driver-side restraint system and validated its accuracy; secondly, it analyzed the kinematic response and damage of the occupants with the protection of the conventional restraint system; and then, based on the characteristics of the occupant’s kinematic response, it put forward three kinds of restraint strategies. The results indicated that incorporating larger airbags and additional knee bolsters could significantly enhance the protective effectiveness of the restraint system. This strategy achieved reduction of 18.9% in HIC15ms, 2.6% in maximum stress on the cervical spine, 17% in maximum chest compression, 4% in maximum rib strain, and 21% in axial force on the legs. The research findings offer valuable insights for the future design of protection systems for reclined occupants.

Analysis of Mechanisms of Mandible Fractures by Lateral Impact: A Biomechanical Approach Using Finite Element Models

Background/Aim: The purpose of this study was to reproduce a lateral fall using a computer simulation model and to clarify the circumstances of mandible fracture caused by a lateral impact. Material and methods: Fall scenarios were reconstructed using a computer simulation with finite element models. The fall condition was set as a fall from the head direction, which would cause facial injuries. In each simulation, the effective plastic strain of the mandible and its site were determined. Analysis of variance was performed to determine which factors had a significant effect on the maximum effective plastic strain of the mandible. Results: Significant differences with p-values less than 0.001 were found for the following factors: pitch angle, lateral bending angle, impact object, combination of pitch angle and lateral bending angle, and combination of pitch angle and impact object. In most cases with higher values of effective plastic strain, which can cause mandibular fractures, the site was found at the condylar process or mandibular angle of the attacked side. Conclusion: If the patient falls laterally and their face makes contact with a protruding object, medical professionals can predict fractures of the upper part of the mandibular angle and the condyle of the affected side.

Study on the safety distance determination model for natural gas wells in Ordos Basin subsidence areas of coal mining

To optimize the safe distance between coal mining faces and natural gas wells, with the Ordos Basin as the engineering background for the intersectional development of natural gas and coal resources, a Gaussian function equation for subsidence curves under complete mining was proposed based on the probability integral method, and a model was constructed to determine the coordinated mining safety distance between coal mining faces and natural gas wells. Based on the distributed optical fiber monitoring principle of the BOTDR technology, on-site monitoring of the simulated monitoring well GX1 within the safety distance was carried out. The results indicated that the maximum strain change values of the outer casing and inner production casing of the simulated monitoring well GX1 were 836 με and 766 με, respectively, far less than the maximum ultimate tensile strain value of the overlying rock at the same depth position. Furthermore, the casing structure possessed ample resistance capability, ensuring no noticeable deformation occurred. Through comparison, it was found that the discriminant model reduced the reserved safety distance between the coal mining working face and the natural gas well by 58% compared with the currently used avoidance method of the surface subsidence boundary, liberated coal resources, and achieved a "win–win" situation of the coordinated mining of natural gas resources and coal resources. It can reasonably adjust the coordinated mining problem without a natural gas-coal co-mining mechanism, provide a new method for the layout of natural gas wells in gas-coal overlapping areas, and provide new ideas for the coordinated mining of coal-related associated resources.

Dynamic Failure Mechanism and Fractal Features of Fractured Rocks Under Quasi-Triaxial Static Pressures and Repeated Impact Loading

Mastering the dynamic mechanical behaviors of pre-stressed fractured rocks under repeated impact loads is crucial for safety management in rock engineering. To achieve this, repeated impact loading experiments were performed on produced fractured samples exposed to varying pre-applied axial and confining pressures using a split Hopkinson pressure bar test system in combination with a nuclear magnetic resonance imaging system, and the dynamic failure mechanism and fractal features were investigated. The results indicate that the dynamic stress–strain curves exemplify typical class II curves, and the strain rebound progressively diminishes with growing impact times. The impact times, axial pressure, and confining pressure all significantly affect the dynamic peak strength, average dynamic strength, dynamic deformation modulus, average dynamic deformation modulus, maximum strain, and impact resistance performance. Moreover, under low confining pressures, numerous shear cracks and tensile cracks develop, which are interconnected and converge to form large-scale macroscopic fracture surfaces. In contrast, specimens under a high confining pressure primarily experience tensile failure, accompanied by localized small-scale shear failure. Under low axial pressure, some shear cracks and tensile cracks emerge, while at high axial pressure, anti-wing cracks and secondary coplanar cracks occur, characterized predominantly by shear failure. In addition, as the confining pressure grows from 8 to 20 MPa, the fractal dimensions are 2.44, 2.32, 2.23, and 2.12, respectively. When the axial pressures are 8, 14, and 20 MPa, the fractal dimensions are 2.44, 2.46, and 2.52, respectively. Overall, the degree of fragmentation of the sample decreases with growing confining pressure and grows with rising axial pressure.

The Effect of Locking Head Inserts on the Biomechanical Properties of a 3.5-mm Broad Locking Compression Plate When Used in an Open Fracture-Gap Model.

To determine the effect of locking head inserts (LHI) on plate strain, stiffness, and deformation when applied to a 3.5-mm broad locking compression plate (LCP) in an open fracture-gap model. Six, 13-hole, 3.5-mm broad LCP were secured to epoxy bone models with a 10 mm central defect and 1 mm plate offset. Two peripheral locking screws were placed in each segment, with the remaining screw holes left unfilled. Three strain gauges were glued to each LCP at anticipated regions of maximum strain. Constructs underwent cyclic uniaxial loading at a rate of 20 mm/min to 400 N in three different configurations (Configuration 1: no LHI, Configuration 2: 3 LHI, Configuration 3: 9 LHI). LHI were tightened to 4 Nm of torque. A data acquisition system was used to collect implant strain during testing. Construct stiffness and deformation were recorded by the biomechanical testing machine. Maximum implant strain was recorded at the central screw hole directly over the simulated fracture gap in all configurations (Mdn 1,837.3 µε [interquartile range: 1,805.1-1,862.0]). There was no difference in implant peak-to-peak strain with addition of LHI at all three gauges (Gauge 1 [p = 0.847], Gauge 2 [p = 0.847], Gauge 3 [p = 0.311]). Similarly, peak-to-peak displacement (p = 0.069) and axial construct stiffness (p = 0.311) did not change with the addition of LHI. The addition of LHI to a 3.5-mm broad LCP construct was not shown to have an effect on plate strain, stiffness, or deformation.

Research on hot deformation characterization of a new weathering steel through processing map and microstructural observation

Investigations using hot compression tests on a new high-strength weathering steel revealed specific deformation behaviors across different conditions. These tests were performed at temperatures ranging from 850 to 1050 °C and at strain rates from 0.01 to 5 s−1. Results indicated that a decrease in the deformation temperature combined with an increase in strain rate notably enhanced both the maximum stress and strain achieved. Notably, above 900 °C and with strain rates below 0.1 s−1, the flow stress of the material reached a steady state at certain strain levels. At a strain rate of 1 s−1, irrespective of the temperature, the steel shows a continuous strain hardening behavior, achieving no stable flow stress state. Notably, when the true strain exceeds 0.8, an unusual increase in flow stress occurs, predominantly due to secondary work hardening effects. The microstructural changes in the deformed samples were examined using electron backscatter diffraction (EBSD), which helped elucidate the softening mechanisms inherent in this high-strength steel. Further, processing maps developed from true strains of 0.1–0.9, derived from the experimental flow stress data, suggest controlling the strain within 0.2–0.4 to minimize instability during hot working.

Microstructure and Thermal Cyclic Behavior of FeNiCoAlTaB High-Entropy Alloy.

This study investigates the grain morphology, microstructure, magnetic properties and shape memory properties of an Fe41.265Ni28.2Co17Al11Ta2.5B0.04 (at%) high-entropy alloy (HEA) cold-rolled to 98%. The EBSD results show that the texture intensities of the samples annealed at 1300 °C for 0.5 or 1 h are 2.45 and 2.82, respectively. This indicates that both samples were formed without any strong texture. The grain morphology results show that the grain size increased from 356.8 to 504.6 μm when the annealing time was increased from 0.5 to 1 h. The large grain size improved the recoverable strain due to a reduction in the grain constraint. As a result, annealing was carried out at 1300 °C/1 h for the remainder of the study. The hardness decreased at 24 h, then increased again at 48 h; this phenomenon was related to the austenite finish temperature. Thermo-magnetic analysis revealed that the austenite finish temperature increased when the samples were aged at 600 °C for between 12 and 24 h. When the aging time was prolonged to 48 h, the austenite finish temperature value decreased. X-ray diffraction (XRD) demonstrated that the peak of the precipitates emerged and intensified when the aging time was increased from 12 to 24 h at 600 °C. From the three-point bending shape memory test, the samples aged at 600 °C for 12 and 24 h had maximum recoverable strains of 2% and 3.6%, respectively. The stress-temperature slopes of the austenite finish temperature were 10.3 MPa/°C for 12 h and 6 MPa/°C for 24 h, respectively. Higher slope values correspond to lower recoverable strains.

Position-based assessment of head impact frequency, severity, type, and location in high school American football.

Research on head impact characteristics, especially position-specific investigations in football, has predominantly focused on collegiate and professional levels, leaving a gap in understanding the risks faced by high school players. Therefore, this study aimed to investigate the effect of three factors-player position, impact location, and impact type-on the frequency, severity, and characteristics of impacts in high school American football. Additionally, we examined whether and how player position influences the distribution of impact locations and types. Sixteen high school football players aged 14 to 17 participated in this study. Validated mouthguard sensors measured head impact kinematics, including linear acceleration, angular acceleration, and angular velocity across ten games, and were used to identify impact locations on the head. Video recordings verified true impacts, player position, and impact type at the moment of each recorded impact. Head impact kinematics were input into a head finite element model to determine the 95th percentile of the maximum principal strain and strain rate. Several novel and systematic approaches, such as normalization, binning, and clustering, were introduced and utilized to investigate the frequency and severity of head impacts across the three aforementioned factors while addressing some of the limitations of previous methodologies in the field. To that end, the number of recorded impacts for each player position during each game was divided by the number of players in that position, and then averaged across ten games. Instead of averaging, impacts were categorized into four severity bins: low, mid-low, mid-high and high. Clusters for the three factors were also identified according to the characteristics of impacts. Results revealed that offensive linemen and running backs experienced a higher normalized frequency and more severe impacts across all head kinematics and brain tissue deformation parameters. Frontal impacts, resulting from "head-to-head" impacts, were the most frequent and severe impact locations. The distributions of impact location and type for each specific position were distinct. Offensive linemen had the highest proportion of frontal impacts, while quarterbacks and centerbacks had more impacts at the rear location. These findings can inform interventions in game regulations, training practices, and helmet design to mitigate injury risks in high school football.

Numerical analysis of the hydraulic fracture propagation behavior encountering gravel in conglomerate reservoirs

Hydraulic fracturing, which forms complex fracture networks, is a common technique for efficiently exploiting low-permeability conglomerate reservoirs. However, the presence of gravel makes conglomerate highly heterogeneous, endowing the deformation, failure, and internal micro-scale fracture expansion mechanisms with uniqueness. The mechanism of fracture expansion when encountering gravel in conglomerate reservoirs remains unclear, challenging the design and effective implementation of hydraulic fracturing. This paper utilizes the Abaqus platform and adopts the maximum circumferential strain fracture criterion to establish a two-dimensional fluid-solid-structure coupled fracture expansion model. The study investigates the impact of permeability, Young’s modulus, in-situ stress difference, and incidence angle on the fracture expansion behavior in the presence of gravel. The results indicate that low-permeability gravel induces pressure changes near the fracture tip, like 13% pore pressure increase and stress reductions. Shear stress on the gravel surface rises by 28.3%, and choosing layers with a smaller permeability gap between matrix and gravel can reduce complex near-well fractures. High Young’s modulus gravel has a stress shielding effect around fractures, which is direction-dependent, with over tenfold stress variations. It causes a 60.7% increase in peak shear stress on the gravel surface, exacerbating fracture complexity and reducing extension distance, and a greater strength disparity between gravel and matrix enhances this effect. A high in-situ stress difference (over 8 MPa) weakens gravel-caused stress shielding, leading to stable fracture propagation with a single morphology and increased extension distance, though not favoring complex network formation. As the incidence angle rises, the gravel’s impact on stress and seepage fields weakens, but the risk of shear failure on the cementation interface increases. The findings provide a basis for optimizing operations in such reservoirs considering the various properties of gravel and their effects on fluid flow and fracture behavior.

Numerical evaluation of the internal fracture mechanism of horizontal loop connections in precast elements under the influence of transverse reinforcement

AbstractThis study numerically evaluated the flexural capacity and fracture mechanism of precast reinforced concrete beams connected with in situ horizontal loop connections employing the three‐dimensional rigid body spring model (3D‐RBSM) for modeling of concrete and beam elements (BEs) for modeling of steel, respectively. The research analyzed the performance of continuous horizontal loop connections with and without transverse reinforcement, considering varying vertical spacing between loops and transverse steel ratios. The numerical model effectively captured the test load displacement relationships by incorporating the model parameters like Young's modulus, tensile strength, fracture energy, compressive strength, cohesion, and angle of internal friction for concrete along with mechanical properties of steel and revealed that loop joints without transverse reinforcement exhibited loop type failure. In contrast, specimens with transverse reinforcement improved the peak load and caused compression failure. It was discovered that transverse rebars on the continuous side of the joint experience more strain; particularly, the maximum strain occurred in the corner rebars within the curved sections of U‐rebars. Moreover, the increased vertical spacing between the loop rebars increased the diagonal crack propagation and demonstrated the loop‐type failure. Further, a larger circumferential area of transverse rebar offered greater bond strength and confinement to the concrete core and reproduced the maximum deformation capacity, ductility, and compression failure.

Biomechanical and clinical assessment of dissociation in bipolar hip hemiarthroplasty

Background Dissociation is a special type of dislocation that is rarely seen in bipolar hemiarthroplasty. Objectıve To investigate the clinical and biomechanical causes of dissociative dislocation of acetabular cup components in the hips of patients after bipolar hemiarthroplasty (BHA). Methods BHA heads were divided into three groups according to their design. Cam-out and pull-out biomechanical tests were conducted to investigate the separation strengths of the BHA heads. Results Among the 1684 BHA surgeries performed, the revision surgery rate was 4% (68 hips) and dissociation rate was 0.8% (15 hips). According to the cam-out test result, the highest values in the parameters ultimate force (Fmax) ultimate torque (T), vertical displacement at maximum force (δm), rotation at maximum force (ϕm), maximum principal strain (Ɛmax), minimum principal strain (Ɛmin), average normal strain (Ɛav), maximum shear strain (γmax), uniaxial normal strain (Ɛun) were detected in Type 2 BHA head. The pull-out values of the implants were sufficient to prevent the distraction force that may occur on the implant due to manual traction applied to the hip dislocations. However, in closed reduction maneuvers, cam-out-shaped deformation forces may cause dissociation in Types 1 and 3, but not in Type 2 BHA heads. According to the pull-out test results, while high values were detected in the parameters Fmax and stiffness ( k) in the Type 2 BHA head, δm and maximum force (E) parameters were found to be high in the Type 1 BHA head. In the cam-out test, a strong positive relationship was found between the thickness and width of the polyethylene locking ring and Fmax, T, δm, ϕm, Ɛmax, γmax, Ɛun. Conclusıon Better BHA head designs and polyethylene designs may help resolve the rare problem of dissociation, which almost always leads to resurgical procedures.

Swin UNETR Segmentation with Automated Geometry Filtering for Biomechanical Modeling of Knee Joint Cartilage.

Simulation studies, such as finite element (FE) modeling, offer insights into knee joint biomechanics, which may not be achieved through experimental methods without direct involvement of patients. While generic FE models have been used to predict tissue biomechanics, they overlook variations in population-specific geometry, loading, and material properties. In contrast, subject-specific models account for these factors, delivering enhanced predictive precision but requiring significant effort and time for development. This study aimed to facilitate subject-specific knee joint FE modeling by integrating an automated cartilage segmentation algorithm using a 3D Swin UNETR. This algorithm provided initial segmentation of knee cartilage, followed by automated geometry filtering to refine surface roughness and continuity. In addition to the standard metrics of image segmentation performance, such as Dice similarity coefficient (DSC) and Hausdorff distance, the method's effectiveness was also assessed in FE simulation. Nine pairs of knee cartilage FE models, using manual and automated segmentation methods, were developed to compare the predicted stress and strain responses during gait. The automated segmentation achieved high Dice similarity coefficients of 89.4% for femoral and 85.1% for tibial cartilage, with a Hausdorff distance of 2.3mm between the automated and manual segmentation. Mechanical results including maximum principal stress and strain, fluid pressure, fibril strain, and contact area showed no significant differences between the manual and automated FE models. These findings demonstrate the effectiveness of the proposed automated segmentation method in creating accurate knee joint FE models. The automated models developed in this study have been made publicly accessible to support biomechanical modeling and medical image segmentation studies ( https://data.mendeley.com/datasets/dc832g7j5m/1 ).

Boosting the Actuation Performance of a Dynamic Supramolecular Polyurethane-Urea Elastomer via Kinetic Control.

The ongoing soft actuation has accentuated the demand for dielectric elastomers (DEs) capable of large deformation to replace the traditional rigid mechanical apparatus. However, the low actuation strain of DEs considerably limits their practical applications. This work developed high-performance polyurethane-urea (PUU) elastomers featuring large actuation strains utilizing an approach of kinetic control over the microphase separation structure during the fabrication process. Additionally, disulfide (DS) bonds were incorporated as dynamic chemical linkages to effectively heal the mechanical damage in the resulting elastomer (PUUDS). Alteration in processing conditions creates notable differences in the rate of phase separation among the multiphase materials. A faster phase separation rate is associated with a reduced degree of microphase separation, increased spacing within hard domains, a higher proportion of disordered hydrogen bonds, and hydrogen bonding index. These changes synergistically improved the electromechanical properties of the PUUDS elastomers, thereby enhancing their actuation performance. The sample processed under the fastest phase separation condition showed the lowest Young's modulus and a pronounced dielectric response at low frequencies. The electrostriction effect accounts for 89% of the total electromechanical coupling, achieving a significant reduction in the driving voltage during actuation. The maximum actuation strain recorded was 21.6% at an electric field of 45 MV/m. Benefiting from the fully reversible dynamic network, the damaged PUUDS elastomer can be healed and restored to its original elongation at break after 3 h at room temperature. Practical application was demonstrated through the development of a miniature butterfly model constructed from a single-layer PUUDS elastomer, showcasing potential applications in soft robotics. These findings highlight the critical role of kinetic control in optimizing the performance of advanced DEs.

Studying the effect of processing parameters on the microstructure, strength, hardness, and corrosion characteristics of friction stir dissimilar welded AA5083 and AA7075 aluminum alloys reinforced with Al-SiC matrix.

The complementary properties of corrosion resistance and ballistic resistance of AA5083 and AA7075, respectively, explain the significance of welding these two alloys in the marine armor industry. This study investigates a novel Al-SiC matrix reinforcement with a different SiC weight ratio in dissimilar friction stir welding of the AA5083/AA7075 joint at different transverse and rotational speeds. The study deduced that the novel matrix can play an important role in improving strength and ductility simultaneously. Maximum strength takes place under conditions of 50% SiC in Al-SiC matrix, 900rpm rotational speed, and 40mm/min transverse speed of value 209.8MPa, which is equal to 90% strength of the base metal AA5083, and the maximum strain takes place at 25% SiC in Al-SiC matrix, 900rpm rotational speed, and 20mm/min transverse speed, with improved strain by 2% than the softer alloy AA5083. Corrosion weight loss decreased by increasing the SiC weight ratio in the Al-SiC matrix, where it improved by 47.9% compared to the base metal alloy of AA5083 at 75% SiC in the Al-SiC matrix, 900rpm rotational speed, and 20mm/min transverse speed.

Study on the mechanical properties and failure mechanism of a multi-lithologic layered rock mass.

The mechanical properties of multi-lithologic reservoir rock masses are complex, and the failure mechanism is not clear. This research belongs to the field of oil and gas exploration and development. Brazilian splitting, and digital image correlation (DIC) tests were performed to study the mechanical properties and failure mechanism of assemblages containing sandstone, shale, and limestone. In the Brazilian splitting test, the tensile strength of the rock mass first increased and then decreased with an increasing angle. As the interface angle increased, The morphology of the splits is also changing. In the DIC test, according to the deformation characteristics at different angles, the Brazilian splitting test process was summarized into three stages: interface deformation, elastoplastic, and failure, the interface has a great influence on the fracture propagation, and the fracture tends to expand along the interface. Interface characteristics were studied based on 3D scanning technology and fractal method, with an increase in the angle, the fractal dimension D showed first decreased, then increased, and further decreased, which was identical to the variation trend of the maximum load in the Brazilian splitting test and the maximum principal strain in the DIC test with the angle. This study provides reference for predicting fracture propagation trend in field hydraulic fracturing work.

Degeneration of the nucleus pulposus affects the internal volumetric strains and failure location of adjacent human metastatic vertebral bodies.

Intervertebral disc (IVD) degeneration is suspected to affect the distribution of stress and strain near the vertebral endplates and in the underlying bone. This scenario is worsened by the presence of metastatic lesions on the vertebrae (primarily thoracic vertebrae (60-80%)) which increase the risk of fracture. As such, this study aimed to evaluate the effect of IVD degeneration on the internal volumetric strains and failure modes of human metastatic vertebral bodies. Five human thoracic spinal segments including one vertebra with lytic metastases and one radiologically healthy vertebra (control) were in-situ tested in pure compression within a mCT scanner (isotropic voxel size = 39 mm). Each specimen was tested in the elastic regime before and after inducing mock IVD degeneration (enzymatic degeneration with collagenase); and at failure after IVD degeneration. The volumetric strain field was measured using a global Digital Volume Correlation approach (BoneDVC). After IVD degeneration, larger maximum (+187%, P = 0.002, 95% CI= [-4447, -1209]) and minimum (+174%, P = 0.002, 95% CI= [1679, 4258]) principal strains were observed in both metastatic and control vertebrae, with peak differences in correspondence of the IVD anulus fibrosus. IVD degeneration caused a transversal fracture pattern in the vertebrae with failure location onset in the middle portion of the vertebral body and in the cortical shell. In conclusion, IVD degeneration was found to be a key factor in determining the failure mode, suggesting the clinical relevance of including IVD level of degeneration to assess patients' risk of spinal instability. STATEMENT OF SIGNIFICANCE: Vertebrae can be affected by pathologies, like bone metastases, while intervertebral discs tend to degenerate during life. Generally, these structures and pathologies are studied separately. In this study, we explored the effects of artificial intervertebral disc degeneration on the mineralised tissues of the vertebrae with metastases. We observed that the induced intervertebral disc degeneration changes the mechanical behaviour of the vertebral trabecular bone. We believe that the findings of this study may influence the scientific community to develop new clinical tools for the prediction of the risk of fracture in vertebrae with spinal metastases, including the degeneration of the intervertebral discs as a parameter.