Joint Reaction Research Articles

Simulation Study of the Upper-limb Isometric Wrench Feasible Set with Glenohumeral Joint Constraints.

The aim of this work is to improve musculoskeletal-based models of the upper-limb Wrench Feasible Set i.e. the set of achievable maximal wrenches at the hand for applications in collaborative robotics and computer aided ergonomics. In particular, a recent method performing wrench capacity evaluation called the Iterative Convex Hull Method is upgraded in order to integrate non dislocation and compression limitation constraints at the glenohumeral joint not taken into account in the available models. Their effects on the amplitude of the force capacities at the hand, glenohumeral joint reaction forces and upper-limb muscles coordination in comparison to the original iterative convex hull method are investigated in silico. The results highlight the glenohumeral potential dislocation for the majority of elements of the wrench feasible set with the original Iterative Convex Hull method and the fact that the modifications satisfy correctly stability constraints at the glenohumeral joint. Also, the induced muscles coordination pattern favors the action of stabilizing muscles, in particular the rotator-cuff muscles, and lowers that of known potential destabilizing ones according to the literature.

Concomitant osteochondral lesion of the talus affects in vivo ankle kinetics in patients with chronic ankle instability.

This cross-sectional study aimed to investigate the in vivo ankle kinetic alterations in patients with concomitant chronic ankle instability (CAI) and osteochondral lesion of the talus (OLT), which may offer opportunities for clinician intervention in treatment and rehabilitation. A total of 16 subjects with CAI (eight without OLT and eight with OLT) and eight healthy subjects underwent gait analysis in a stair descent setting. Inverse dynamic analysis was applied to ground reaction forces and marker trajectories using the AnyBody Modeling System. One-dimensional statistical parametric mapping was performed to compare ankle joint reaction force and joint moment curve among groups. The patients with OLT showed significantly increased dorsiflexion moment in the ankle joint compared with healthy subjects during 38.2% to 40.9% of the gait cycle, and increased eversion moment in the ankle joint compared with patients without OLT during 25.5% to 27.6% of the gait cycle. Compared with healthy subjects, the patients with OLT showed increased anterior force during 42% to 43% of the gait cycle, and maximal medial force (p = 0.005, ηp2 = 0.399). The patients with concomitant CAI and OLT exhibit increased dorsiflexion and eversion moment, as well as increased anterior and medial ankle joint reaction force during stair descent, compared with patients with CAI but without OLT and healthy subjects, respectively. Thus, a rehabilitative regimen targeting excessive ankle dorsiflexion and eversion moment may help to reduce ankle joint loading.

Estimation of Joint Kinetics During Manual Material Handling Using Inertial Motion Capture: A Follow-Up Study.

Musculoskeletal models based on inertial motion capture (IMC) and ground reaction force (GRF) prediction hold great potential for field-based risk assessment of manual material handling (MMH). However, previous evaluations have identified inaccuracies in the methodology's estimation of spinal forces, while the accuracy of other key outcome variables is currently unclear. This study evaluated knee, shoulder, and L5-S1 joint reaction forces (JRFs) derived from a musculoskeletal model based on inertial motion capture and GRF prediction against a model based on simultaneously collected optical motion capture (OMC) and force plate measurements. Data from 19 healthy subjects performing lifts with various horizontal locations (HLs), deposit heights (DHs), and asymmetry angles (AAs) were analyzed, and the consistency and absolute agreement of the model estimates statistically compared. Despite varying levels of agreement across tasks and variables, considerable absolute differences were identified for the L5-S1 axial compression (AC) (root-mean-square error (RMSE) = 63.0-94.2%BW) and anteroposterior (AP) shear forces (RMSE = 40.9-80.6%BW) as well as the bilateral knee JRFs (RMSE = 78.9-117%BW). Glenohumeral JRFs and vertical GRFs exhibited the highest overall consistency (r = 0.33-0.91, median 0.78) and absolute agreement (RMSE = 7.63-34.9%BW), while the L5-S1 axial compression forces also showed decent consistency (r = 0.04-0.89, median 0.80). The findings generally align with prior evaluations, indicating persistent challenges with the accuracy of key outcome variables. While the modeling framework shows promise, further development of the methodology is encouraged to enhance its applicability in ergonomic evaluations.

Lower limb joint loading during high-impact activities: implication for bone health.

Osteoporosis results in low-trauma fractures affecting millions globally, in particular elderly populations. Despite the inclusion of physical activity in fracture prevention strategies, the optimal bone-strengthening exercises remain uncertain, highlighting the need for a deeper understanding of lower limb joint loading dynamics across various exercise types and levels. This study examines lower limb joint loading during high-impact exercises across different intensities. A total of 40 healthy, active participants were recruited (mean ± SD: age of 40.3 ± 13.1yr; height 1.71 ± 0.08m; and mass 68.44 ± 11.67kg). Motion capture data and ground reaction forces of 6 different exercises: a self-selected level of walking, running, countermovement jump, squat jump, unilateral hopping, and bilateral hopping were collected for each participant. Joint reaction forces were estimated using lower body musculoskeletal models developed in OpenSim. Running and hopping increased joint forces compared to walking, notably at the hip (83% and 21%), knee (134% and 94%), and ankle (94% and 77%), while jump exercises reduced hip and ankle loading compared to walking (36% and 19%). Joint loading varied with exercise type and intensity, with running faster increasing forces on all joints, particularly at the hip. Sprinting increased forces at the hip but lowered knee and ankle forces. Higher jumps intensified forces on all joints, while faster hopping reduced forces. The wide variation of lower limb joint loading observed across the exercises tested in this study underscores the importance of implementing diverse exercise routines to optimize overall bone health and strengthen the musculoskeletal structure. Practitioners must therefore ensure that exercise programs include movements that are specifically suitable for their intended purpose.

Greater squat stance width alters three-dimensional hip moment demands

Barbell squat exercise may be performed with different stance widths, which will influence lower limb kinematics and joint reaction forces. Consequently, three-dimensional hip moments may vary with stance width, influencing muscle loading, and the muscles trained when performing squat exercise. To examine how squat stance width affects hip moments, males (n = 11) and females (n = 13) performed barbell squats at narrow, medium, and wide stance widths. Motion capture and force platform data were used to calculate three-dimensional hip net joint moments (NJM) as indicators of the muscular moments required. Hip extensor NJM was greater for wide than medium (P < 0.001) and narrow (P < 0.001) stance squats. Hip adductor NJM was not different between squat stance widths (P = 0.414). Hip lateral rotator NJM was greater in medium versus narrow squats (P < 0.001), and in wide versus medium (P < 0.001) and narrow (P < 0.001) squats. Taken together, the rotational demands at the hip increase as stance width increases, due to higher hip extensor and lateral rotator NJM. In contrast hip adductor NJM is invariant. These data provide insight into the three-dimensional requirements that muscles must meet at the hip when squat exercise is performed at different stance widths.

Effects of a soft back exoskeleton on lower lumbar spine loads during manual materials handling: a musculoskeletal modelling study

The aim of this study was to append a passive soft back exoskeleton to a validated musculoskeletal model and assess its effectiveness in reducing lumbar loads. Fifteen participants lifted a box, with and without wearing a CORFOR® exoskeleton. A full body OpenSim model was used to estimate lumbar joint moments and reaction forces, as well as low back muscles forces. Wearing the exoskeleton reduced the peak flexion moment, muscles forces, as well as peak compressive and shear forces. This musculoskeletal modelling study shows that wearing the exoskeleton may reduce lumbar spine loads and may contribute to prevent low back disorders.

Biomechanical Analysis of the “Cuban Motion”

Abstract Purpose “Cuban Motion” (CM) is a term often used to label a basic movement of many Latin-American dances, such as salsa and bachata. It is characterized by a cyclical and rhythmic flexion and rotation of the pelvis, accompanied by ample movements of the spine and lower limbs. Since Latin dances are considered both a recreational activity and a kind of healthy gymnastics for young and older subjects, a biomechanical analysis of the CM was performed to quantitatively assess the main features of this movement, from joint kinematics to muscle activations. Method The study combined experimental acquisitions with a Vicon Motion Capture system and musculoskeletal analyses in OpenSim. Only one subject was considered, an instructor of Latin dances, who was equipped with 55 retro-reflective markers, according to the Full Body CGM2.5 marker set. Data were processed in OpenSim, using the ThoracoLumbar model (111 DoFs and 620 musculo-tendon actuators). Results The cycle of the CM and its main events were defined. Results showed a wide RoM of many joints, with correlations between hip and knee flexion angles and among list, between hip adduction and shoulder flexion. The main role of the iliopsoas and the ileus costalis muscles was observed. Conclusions The current study quantified the CM as a physical exercise using a biomechanical approach similar to a gait analysis. The main kinematic and kinetic features were described, also providing an estimation of the muscle activations and joint reactions, derived from simulation activity in OpenSim. The main limitation of this study is the focus on a single subject, but this step was necessary to define a context and guidelines for future investigations, where we are going to compare èlite vs. novices and male vs. female dancers.

Assessment of mechanical variables best describing bone remodelling responses based on their correlation with bone density

Density distribution in bones can be estimated using bone remodelling models (BRM) and applying daily normal loads to assess the stress/strain state to which the bone is subjected. These models locally relate a certain mechanical stimulus, derived from the stress/strain state, directly to bone density or to its variation over time. The background of this idea is Frost’s Mechanostat Theory, which states that overloading states tend to increase bone density and disuse states tend to decrease it. Different variables have been proposed in the literature to measure the mechanical stimulus. Strain energy density (SED) and stresses have been commonly used as mechanical stimuli, but to date their use has not been justified with convincing arguments. In this paper we have selected several variables derived from stress and strain tensors and correlated them with the distribution of bone density in the femur of 13 elderly women to conclude which would be most appropriate for use as a mechanical stimulus in a BRM. We have performed this correlation analysis for six different activities: walking normally, fast walking, stair ascent, stair descent, rising from and sitting on a chair, and jumping in place. Musculoskeletal models were used to estimate joint reaction and muscle forces of each individual for each activity. These were applied to the corresponding finite element model of the femur to obtain stress and strain tensors at each point. The variables proposed as mechanical stimulus and derived from these tensors were correlated to the actual density obtained for each individual from CT-scans. Our results show that stress variables are the best correlated with density. In contrast, the correlations of SED are very weak, so it is not a good candidate for mechanical stimulus. Strains are also weakly correlated to density, but in this case because their distribution across the femur is rather uniform. This is in agreement with the Mechanostat Theory which states that bone reacts to load changes by changing its stiffness so to keep strains in a certain interval. Consequently, a plausible choice for a remodelling criterion could be keeping that strain uniformity.

Multi-material 3D printing of functionally graded soft-hard interfaces for enhancing mandibular kinematics of temporomandibular joint replacement prostheses

Temporomandibular joint (TMJ) replacement prostheses often face limitations in accommodating translational movements, leading to unnatural kinematics and loading conditions, which affect functionality and longevity. Here, we investigate the potential of functionally graded materials (FGMs) in TMJ prostheses to enhance mandibular kinematics and reduce joint reaction forces. We develop a functionally graded artificial cartilage for the TMJ implant and evaluate five FGM designs: hard, hard-soft, and three FGM gradients with gradual transitions from 90% hard material to 0%, 10%, and 20%. These designs are 3D printed, mechanically tested under quasi-static compression, and simulated under physiological conditions. Results from computational modeling and experiments are compared to an intact mandible during incisal clenching and left group biting. The FGM design with a transition from 90% to 0% hard material improves kinematics by 19% and decreases perfomance by 3%, reduces joint reaction forces by 8% and 10%, and increases mandibular movement by 20% and 88% during incisal clenching and left group biting, respectively. These findings provide valuable insights for next-generation TMJ implants.

Joint reaction and simulated muscle forces during squatting and walking in persons with hemophilia

BackgroundPersons with hemophilia experience joint bleeding that can lead to debilitating arthropathy, most commonly seen in ankles, knees, and elbows. Arthropathy can hinder participation in daily and athletic activities. We explored how hemophilic arthropathy impacts movement patterns in walking and bilateral squatting tasks in persons with hemophilia compared to healthy controls. MethodsPersons with hemophilia and healthy controls completed walking and squatting tasks while kinematic and kinetic motion capture data were collected. The Hemophilia Joint Health Score exam was performed to measure hemophiliac arthropathy. OpenSim was used to model muscle and joint reaction forces and calculate moments and angles. Peak values were compared using Cohen's d to estimate effect sizes of hemophilia on movement parameters. FindingsNine persons with hemophilia and eight age-matched controls were analyzed. Temporal-spatial metrics were similar between hemophilia and control groups in both tasks. In walking, persons with hemophilia had higher peak ankle dorsiflexion angles, vertical ground reaction force weight acceptance peaks, and hip extension and flexion moments compared to controls. In squatting, persons with hemophilia had lower knee extension moments, ankle joint reaction force, and knee extensor forces, but had higher hip extension moments. InterpretationTemporal-spatial metric similarity between hemophilia and controls suggests that kinetic and kinematic analyses are needed to identify movement pattern differences. These data identify potential compensatory strategies at the hip that may be used by persons with hemophilia to mitigate impact on the knee and ankle. Future work will confirm these data in a larger sample size and be used to develop physical therapy strategies.

The examination of relationships between upper extremity joint lengths, reaction time and shoulder strength parameters in youth canoe athletes

The aim of this study was to investigate the relationships between upper extremity joint length, reaction time and shoulder strength in young canoe athletes. The study was carried out with the voluntary participation of 23 young canoe athletes. Within the scope of the research plan, height measurements, body weight measurements, length measurements of the upper extremities (arm and forearm length), arm span length measurements, reaction time measurements and isokinetic strength measurements of the athletes were carried out. The effect of joint length values on reaction time and shoulder strength parameters was examined by multiple linear regression analysis. The results show that joint length values have a significant effect on reaction time and shoulder strength values in canoe athletes (p

Validation of Markerless Motion Capture for Soldier Movement Patterns Assessment Under Varying Body-Borne Loads.

Field performance of modern soldiers is affected by an increase in body-borne load due to technological advancements related to their armour and equipment. In this project, the Theia3D markerless motion capture system was compared to the marker-based gold standard for capturing movement patterns of participants wearing various body-borne loads. The aim was to estimate lower body joint kinematics, gastrocnemius lateralis and medialis muscle activation patterns, and lower body joint reaction forces from the two motion capture systems. Data were collected on 16 participants performing three repetitions of walking and running under four body-borne load conditions by both motion capture systems simultaneously. A complete musculoskeletal analysis was completed in OpenSim. Strong correlations ( ) and acceptable differences were observed between the kinematics of the marker-based and markerless systems. Timing of muscle activations of the gastrocnemius lateralis and medialis, as estimated through OpenSim from both systems, agreed with the ones measured using electromyography. Joint reaction force results showed a very strong correlation ( ) between the systems; however, the markerless model estimated greater joint reaction forces when compared the marker-based model due to differences in muscle recruitment strategy. Overall, this research highlights the potential of markerless motion capture to track participants wearing body-borne loads.

A Machine Learning Approach for Predicting Pedaling Force Profile in Cycling

Accurate measurement of pedaling kinetics and kinematics is vital for optimizing rehabilitation, exercise training, and understanding musculoskeletal biomechanics. Pedal reaction force, the main external force in cycling, is essential for musculoskeletal modeling and closely correlates with lower-limb muscle activity and joint reaction forces. However, sensor instrumentation like 3-axis pedal force sensors is costly and requires extensive postprocessing. Recent advancements in machine learning (ML), particularly neural network (NN) models, provide promising solutions for kinetic analyses. In this study, an NN model was developed to predict radial and mediolateral forces, providing a low-cost solution to study pedaling biomechanics with stationary cycling ergometers. Fifteen healthy individuals performed a 2 min pedaling task at two different self-selected (58 ± 5 RPM) and higher (72 ± 7 RPM) cadences. Pedal forces were recorded using a 3-axis force system. The dataset included pedal force, crank angle, cadence, power, and participants’ weight and height. The NN model achieved an inter-subject normalized root mean square error (nRMSE) of 0.15 ± 0.02 and 0.26 ± 0.05 for radial and mediolateral forces at high cadence, respectively, and 0.20 ± 0.04 and 0.22 ± 0.04 at self-selected cadence. The NN model’s low computational time suits real-time pedal force predictions, matching the accuracy of previous ML algorithms for estimating ground reaction forces in gait.

Muscular Fatigue Influences Patellofemoral Joint Reaction Force During Cutting In Healthy Females

Muscular Fatigue Influences Patellofemoral Joint Reaction Force During Cutting In Healthy Females

Isolated humeral distalization in reverse total shoulder arthroplasty: a biorobotic shoulder simulator study

BackgroundHumeral distalization is inherent to reverse total shoulder arthroplasty (rTSA) and is often produced with concomitant humeral lateralization via the level of the humeral head cut, implant positioning, implant neck shaft angle, and polymer insert thickness. Biomechanical data on the isolated effects of humeral distalization remain limited but could be important to consider when optimizing postoperative rTSA shoulder function. This study investigated the effects of isolated humeral distalization on shoulder biomechanics using a biorobotic shoulder simulator. MethodsEight fresh-frozen cadaveric shoulders were tested using custom polymer inserts that translated the bearing surface 0, +5, +10, and +15 mm along the humeral stem axis, producing isolated distalization without lateralization. Specimens underwent passive elevation in the scapular plane with a static scapula to assess glenohumeral range of motion. Scapular plane abduction motion trajectories were then performed, driven by previously collected scapulothoracic and glenohumeral kinematics from rTSA patients. The effect of isolated distalization on passive elevation was tested using mixed-effects linear regression and the effect on muscle force, joint reaction force, and muscle excursion during active scapular-plane abduction was tested using statistical parametric mapping random effects analysis. ResultsMaximum passive scapular plane elevation increased with humeral distalization (4° per 5 mm distalization). During active elevation, deltoid and rotator cuff muscle forces, and joint reaction forces, increased up to 37% per 5 mm of distalization. Simulated deltoid muscle excursion was altered with increasing distalization but amounted to no more than 0.8 mm change from baseline per 5 mm of distalization. Rotator cuff muscles were consistently lengthened throughout abduction, up to 1.6 mm per 5 mm of distalization. These trends were observed across various patient motions. ConclusionsIsolated humeral distalization caused dramatic increases in the muscle forces required to perform scapular-plane abduction. Joint reaction forces increased correspondingly. These results suggest that implant and surgical strategies to generate deltoid muscle tension without humeral distalization may promote better active range of motion and more durable long-term outcomes over approaches that rely on distalization.

Habitual Running Style Matters: Duty Factor, and Not Stride Frequency, Relates to Loading Magnitude.

Running style is temporally defined by a duty factor and stride frequency and believed to be related to the loading experienced during ever step. However, the exact relationship between both temporal variables and loading magnitude is still unknown. We aimed to identify the relationship between a duty factor and stride frequency with external load measures, joint reaction forces and joint moments. Thirty-one healthy female recreational runners ran across a 25-m runway at a speed of 2.30 ± 0.05 m·s-1. Ground reaction forces and motion capture data were used to determine the maximal vertical ground reaction force, the vertical instantaneous loading rate, peak braking force, peak joint extension moments and peak joint reaction forces at the knee and the ankle. The habitual duty factor and stride frequency of runners did not correlate with each other. The duty factor was found to be a significant predictor of maximal vertical ground reaction force (R2 = 0.585), peak braking force (R2 = 0.153), peak knee extension moment (R2 = 0.149), ankle plantar flexion moment (R2 = 0.225) and peak joint reaction forces at the knee (R2 = 0.591) and the ankle (R2 = 0.592), but not of the vertical instantaneous loading rate. Stride frequency had no significant predictive value. In conclusion, the maximal loading and potential injury risk of female recreational runners running with high duty factors are lower compared to those of peers running with lower duty factors.

Kinematic–kinetic compliant acetabular cup positioning based on preoperative motion tracking and musculoskeletal modeling for total hip arthroplasty

The invention of the surgical robot enabled accurate component implantation during total hip arthroplasty (THA). However, a preoperative surgical planning methodology is still lacking to determine the acetabular cup alignment considering the patient-specific hip functions during daily activities such as walking. To simultaneously avoid implant edgeloading and impingement, this study established a kinematic–kinetic compliant (KKC) acetabular cup positioning method based on preoperative gait kinematics measurement and musculoskeletal modeling. Computed tomography images around the hip joint and their biomechanical data during gait, including motion tracking and foot–ground reaction forces, were collected. Using the reconstructed pelvic and femur geometries, the patient-specific hip muscle insertions were located in the lower limb musculoskeletal model via point cloud registration. The designed cup orientation has to be within the patient-specific safe zone to prevent implant impingement, and the optimized value selected based on the time-dependent hip joint reaction force to minimize the risk of edgeloading. As a validation of the proposed musculoskeletal model, the predicted lower limb muscle activations for seven patients were correlated with their surface electromyographic measurements, and the computed hip contact force was also in quantitative agreement with data from the literature. However, the designed cup orientations were not always within the well-known Lewinnek safe zone, highlighting the importance of KKC surgical planning based on patient-specific biomechanical evaluations.

Accidents with Lepidoptera (Insecta): Biology, Poisonous, Clinical Manifestations, Treatment, Prevention, and Therapeutic Possibilities

Accidents triggered by contact with winged adult forms of moths and accidents caused by contact with larvae. These accidents are caused by contact with the bristles on the abdomen of females of certain species, belonging to the genus Hylesia Hübner, 1820 (Family: Hemileucidae). Therefore, the simple fact of penetration of the bristles seems to be capable of causing intense inflammatory, popular, and pruritic reactions. Pararama (pararamose) is the common name for a stinging caterpillar found in the artificial rubber plantations of Pará, Brazil, the larval stage of the moth Premolis semirufa (Walker, 1856) (Famíly: Erebidae). Therefore, accidental contact with the small bristles of the caterpillars or with those of the cocoons causes a chronic inflammatory reaction in the interphalangeal joints that leads to ankylosis. The morbid condition mainly affects rubber tappers and is classified as an occupational disease. Eruca=larva; erucism is poisoning caused by a moth larva. The main families of Lepidoptera fireworms that cause erucism accidents are Megalopygidae, Saturniidae, and Arctiidae. The caterpillars of the Megalopygidae family have a body covered with long, harmless bristles that cover the smaller, sharp spines that carry poison glands this manuscript aims to report the biological characteristics of venomous Lepidoptera (Insecta) and their biological, clinical manifestations, treatment, prevention, and therapeutic possibilities. That paper is a narrative review of the literature, which is designed to explain and discuss a certain subject from a theoretical or contextual perspective, to allow the reader to acquire or update knowledge on a specific topic. The scientific articles that made up this review were searched on Google Scholar, Biological Abstract, HAL, Qeios, ResearchGate, Scielo, and SSRN. The following descriptors in Health Sciences (DeCS) were used: biological therapy, larva, wound, debridement, and healing. The following inclusion criteria were considered: original articles and reviews, published nationally and internationally in full, available electronically, and published in Portuguese, English, and Spanish. The exclusion criteria were dissertations, theses, monographs, and conclusion work, duplicates, and those that required payment to access the content in full.

Study on organic carbon in medium-low mature shale oil reservoirs rich in type II kerogen: Oxidation behavior, thermal effect, and kinetics

In-situ combustion technology (ISC) was a potential technology for efficient development of medium–low maturity shale oil reservoirs. Clarifying the exothermic behavior of organic carbon oxidation will be beneficial for better control of ISC processes. In this work, the organic carbon composition, type II kerogen and residual oil, were separated and extracted from the shale samples of typical medium–low maturity shale oil reservoirs in the Ordos Basin, China. The synchronous thermal analyzer and mass spectrometry (STA-MS), Fourier transform infrared spectroscopy (FTIR), and ROCK-EVAL VI were used to study the products, heat release, and functional group changes of type II kerogen, residual oil, and shale during the oxidation process. The results indicated that the oxidation heat release of shale mainly came from the oxidation reaction between its residual oil and type II kerogen, but the oxidation heat release range of shale was relatively lagging compared to the single residual oil or type II kerogen affected by rock debris. Secondly, under atmospheric pressure, the type II kerogen experiences obviously higher heat release than residual oil and heavy oil, indicating its superior potential of in-situ heat release. In addition, the major productions that CO, H2O, SO2, and CO2 were quantitatively characterized, with CO2 having the highest production of 882.25 mg/g. Furthermore, combined with the molecular weight, an oxidation reaction equation of type II kerogen was constructed. Finally, the oxidation kinetics parameters of type II kerogen, residual oil, and shale were determined using Friedman and Ozawa-Flynn-Wall (OFW) models. It was found that the activation energy of shale was higher than II kerogen and residual in low temperature oxidation (LTO) and fuel deposition (FD) stages. This may be due to the joint reaction between kerogen and residual oil, thus exacerbating the challenge of shale in-situ ignition. However, due to the catalytic effect of rock debris, the activation energy of shale was lower than LTO in high temperature oxidation (HTO) stage, indicating that once fuel deposition was completed, organic carbon will undergo stable combustion. This study has theoretical guidance for the numerical simulation research of ISC development technology of maturity-low shale oil reservoirs.

A novel method for reducing the brazing temperature of C/C composite with TiZrHfTa/Ni composite interlayers

C/C composite was successfully brazed with TiZrHfTa/Ni composite interlayers at lower temperature far below the melting point of TiZrHfTa refractory high entropy alloy. The influence of brazing parameters on the joint morphology, indentation fraction toughness of the reaction layer, shear strength at room temperature and at 1000 °C, and fracture behavior was investigated. The results show that all of the C/C composite joints contained two main phases: an equimolar (Ti-Zr-Hf-Ta)C hard phase and a near-pure Ni binder phase. The maximum indentation fracture toughness of the obtained joint reaction layer material was 15.52 ± 0.64 MPa·m1/2. This was proved to be beneficial to improve the strength and toughness of the joint. Meanwhile, the maximum shear strengths of C/C-TiZrHfTa/Ni-C/C joint at room temperature and at 1000 °C reached 33.24 ± 1.85 MPa and 21.70 ± 2.12 MPa, respectively. Abundant slip lines, in-situ dimples, and tearing ridges resulting from Ni plastic deformation suggest a predominantly ductile fracture mode in the joint. This work introduces an innovative method, which can not only ensure the service of C/C composite in high temperature environment, but also effectively reduce the joining temperature.