Axial Rod Research Articles

Study of Rewetting Behavior in AHWR Fuel Cluster During Loss of Coolant with Water Jet Impingement

This study investigates the rewetting behavior of an Advanced Heavy Water Reactor (AHWR) fuel rod bundle during a loss-of-coolant accident using computational fluid dynamics simulations with ANSYS CFX. The analysis focuses on the cooling effectiveness of radial jet impingement at varying flow rates and its impact on rewetting temperature and wetting delay. Simulations were conducted by maintaining a constant initial wall temperature, with cooling curves and contour profiles extracted from various angular positions along the axial rod surfaces. The results reveal that rewetting is faster near the jet sections due to enhanced coolant interaction, while areas farther from the jets exhibit delayed wetting and elevated wall temperatures, where vapor accumulation hinders heat dissipation. Higher flow rates minimize wetting delays and improve cooling by promoting transition and nucleate boiling. However, irregular coolant splashing and vapor dominance disrupt the uniformity of rewetting across the bundle. The study highlights the limited impact of increased flow rates on achieving consistent rewetting along the entire rod length, with substantial fluctuations observed in cooling performance at different vertical positions. The findings emphasize the need for further research under high-temperature steam conditions to better understand boiling mechanisms and improve the stability of emergency cooling systems in nuclear reactors.

Novel rod-sprung-mass model to investigate characteristics of building structural vibration induced by railways

Railway-induced vibrations in building structures require predictions to assess the serviceability. Fundamental properties such as the predominant modes of railway-induced vibrations are critical in structural design and mitigation approaches. However, the existing numerical models are customised to specific buildings. This renders these models unsuitable for broader mechanistic investigations. To address this, this study proposes a rod-sprung-mass (RSM) model to investigate the dynamic behaviour of structures under vertical ground excitations induced by railways. The columns were modelled as axial vibration rods, with each floor suspended on the rod as a sprung mass. The model was validated using a three-story steel frame structure and a five-story concrete structure. Subsequently, the dynamic characteristics of the structures and railway-induced responses were discussed. The structural vertical modes are attributed to the interaction between the columns and slabs, and the structural natural frequencies are outside the frequency range of the individual components. Parametric studies revealed that lower-order structural modes are generally predominant. Under such circumstances, the floor response tends to first decrease and subsequently increase with the floor height. As a result, low-rise buildings exhibit the maximum amplitude on the top floor, whereas the maximum amplitude is on the ground floor for high-rise buildings. Meanwhile, when structural high-order modes become predominant owing to a high-frequency input, the responses of the middle floors intensify, and the peak responses can be altered to the middle floors. This study emphasises the necessity of considering vertical global modes, whereas existing studies have focused mainly on mode shapes on particular floors. The RSM model is an efficient tool for structural design and vibration control.

Axial rod slip at the end-of-construct screw in scoliosis surgery: relevance, occurrence and prevention

PurposeDespite standardized biomechanical tests for spinal implants, we recently recognized pedicle screw failure to maintain the rod fixated as a clinical concern in scoliosis surgery. This occurrence study investigates the risk and magnitude of axial rod slip (ARS), its relation with technique and preventive measures.MethodsRetrospective multicenter review of all primary scoliosis cases (2018–2020) with > 1 year FU from three centers, instrumented with uniplanar screws and 5.5 mm CoCr rods (Mesa 2, Stryker Corporation, Kalamazoo, MI, USA). ARS was defined as > 1 mm change in residual distal rod length from the screw in the lowest instrumented vertebra (LIV) and assessed by two independent observers. Slip distance, direction, relation to distal screw density and time of observation were recorded, as well as the effect of ARS on caudal curve increase. To prevent slip, more recent patients were instrumented with a different end-of-construct screw (Reline, NuVasive Inc. San Diego, CA, USA) and analyzed for comparison.ResultsARS risk was 27% (56/205) with a distance of 3.6 ± 2.2 mm, predominantly convex. 42% occurred before 4 months, the rest before 1 year. The caudal curve substantially increased three times more often in patients with ARS. Interobserver reliability was high and slip was in the expected direction. ARS was unrelated to distal screw density. Remarkable variation in ARS rates (53%, 31%, 13%) existed between the centers, while there was no difference in mean screw density (≈1.3 screws/level) or curve correction (≈60%). Revision surgery for ARS was required in 2.9% (6/207). Using the different end-of-construct screw, ARS risk was only 2% (1/56) and no revisions were required.ConclusionThis study demonstrates the prevalence of axial rod slip at the end of construct in scoliosis surgery and its clinical relevance. While minimal ARS can be subclinical, ARS should not be mistaken for adding on. The most severe ARS predominantly occurred convex at the high-loaded distal screw when L3 was the LIV. Longer constructs (LIV L3 or L4) have a higher risk of ARS. The minimal risk of ARS with another end-of-construct screw underscores the influence of screw type on ARS occurrence in our series. Further research is essential to refine techniques and enhance patient outcomes.

Laser-driven acceleration of a 94.8 MeV uniform proton beam enhanced by a thin axial absorber rod

Laser-based proton accelerators offer promising advantages for many sensitive applications due to their compact size. However, achieving uniform beams with a narrow energy spread remains a challenge. Here, a beamline simulation is performed using the racein and codes to optimize the spectral and spatial characteristics of a laser-driven proton beam. This beamline, comprised of four magnetic quadrupoles and equipped with a thin axial absorber rod in conjunction with an energy selection aperture for narrowing the energy spread, a carbon scatterer foil for beam spot smoothing, and an angular selection aperture for beam collimation, effectively transports a selected proton beam energy within the range of 50–250 MeV. In this work, laser-accelerated protons with a wide energy spread were transported through the proposed beamline, which was optimized for 109 MeV protons. The protons emerged well-collimated with a significantly narrowed energy spread of 94.8±3.9 MeV (a reduction from the intended 109 MeV due to passage through the scatterer) and a homogenized, 11 mm diameter beam spot while maintaining a transmission efficiency above 2.2%. Published by the American Physical Society 2024

Development of a Benchmark for Thermal Striping in Gas-Cooled Fast Reactors

This paper presents the development of a benchmark for predicting thermal striping through simulation. This work utilized large eddy simulation and will be used to benchmark future models. The testing domain was created using both the STRUCT and the Reynolds-averaged Navier-Stokes turbulence models and is based on an earlier design of the General Atomics Fast Modular Reactor upper plenum. The plenum features two adjacent, identical hexagonal bundles each with a center-placed axial rod drive, with a hot left coolant stream and a cold right coolant stream. The simulation solves the nondimensional Navier-Stokes equations, with temperature accounted as a passive scalar. First- and second-order flow statistics were obtained after 600 convective time units of averaging. The first-order statistics reveal that the hot jet is damped by a recirculatory flow from the near wall. At the same location, the second-order statistics show strong oscillations both in velocity and temperature. The power spectral density was utilized to determine that a low-frequency oscillation occurs here that is within the range of interest for thermal striping. Furthermore, proper orthogonal decomposition was used to identify coherent structures that confirm the oscillatory behavior, indicative of thermal striping. Overall, this benchmark can aid in the development of future models for predicting thermal striping in nuclear reactors, potentially leading to improved reactor safety and performance.

Behavior analysis of energy piles in layered transversely isotropic saturated soils

This paper conducts theoretical research on energy piles in layered saturated transversely isotropic soils under different load forms. Firstly, the Timoshenko beam coupled axial force rod elements is used to simulate the pile elements, and the finite element equilibrium equation for energy single piles is derived accordingly. Then, the extended precise integration method (EPIM) is applied to obtain the fundamental solution of soil, which is regarded as the kernel function of the boundary element method to construct the boundary integral equation. Based on the theory of the coupled finite element method - boundary element method (FEM-BEM), and combined with the equilibrium conditions of force and displacement coordination at the pile-soil interface, the boundary integral equation of soil is coupled with the finite element equilibrium equation of the pile to establish the interaction equation. The calculation results of this method are compared with theoretical solutions and in-site field tests to verify the correctness of this theory. Finally, numerical examples are designed to explore the influence of the parameters of energy piles and soils on the behavior of energy piles in layered saturated transversely isotropic soils under vertical and horizontal loadings.

Fuel fragmentation and relocation (FFR) model in SPACE code PART 1: Development and verification

Ballooning of cladding, which can happen during a loss of coolant accident (LOCA), causes relocation of fragmented fuel. Recently, consideration of fuel fragmentation, relocation, and dispersal (FFRD) phenomena for safety analyses has been requested by a regulatory body. Therefore, new models related to the fuel fragmentation, relocation, and dispersal (FFRD) in SPACE code have been developed. In this study, the FFR model, excluding dispersal, will be discussed. The fuel fragmentation and relocation models, which were developed by Quantum Technology (QT), are modified and developed in SPACE code. In particular, the fuel relocation limitation threshold parameter and the fuel power distribution during relocation are newly developed. The FFR models are also verified with simple known problems. The newly developed and implemented FFR models in SPACE are validated with calculations using Halden IFA-650 test data. The newly developed FFR model in SPACE can reasonably predict the fuel relocation and axial rod temperature distribution due to fuel mass redistribution. However, intensive validation tests including various conditions are necessary to validate the new FFR model in SPACE code.

Indeterminate Continuously Inhomogeneous Beam under End Rotation: A Longitudinal Fracture Study

The present paper describes a theoretical analysis of the effect of the end rotation of a statically indeterminate beam structure on the behaviour of a longitudinal crack. The beam is made of a material that is continuously inhomogeneous along the beam thickness. Besides, the material has non-linear elastic behaviour. The left end of the beam is supported with an axial double rod, while the right end is rigidly fixed. There is no external mechanical loading on the beam. Thus, the only influence on the beam is the rotation of the beam left end. Equations for determination the curvatures and the coordinates of the neutral axes are worked out and solved together with equations for resolving the static indeterminacy. The response of the longitudinal crack to the rotation of the beam left end is studied by deriving the strain energy release rate. For this purpose the balance of the energy in the beam is analyzed. The strain energy release rate is verified by applying the integral, J. A parametric analysis is performed to evaluate the influence of the beam end rotation and other factors on the longitudinal fracture.

Nonlinear nonlocal damping effects under magnetic loads of a ferromagnetic-viscoelastic nanotube exposed to a nonlinear elastic medium with nonlocal viscosity

This study presents innovative results on a nonlinear dynamic model of a ferromagnetic-viscoelastic nanotube (FVN) whose dissipation effects are captured by material behavior with a linear dissipation law operating in a nonlinear geometric regime. It investigates a possible system derived from a Kelvin–Voigt type dissipation model that describes internal viscoelastic damping in the form of a parallel spring and a dashpot. In addition, a class of losses by linear viscous media in local and nonlocal damping is presented in the modeling. Magnetic load effects are studied using axial rod theory regardless of rotational inertia and shear effects. The governing equation is derived by Hamilton's principle for the FVN subjected to a transverse magnetic field resting on a nonlinear elastic foundation with viscose effects. Formulas have been developed to obtain the nonlinear damping characteristics of a single-walled nanotube. Then, multiple scale method (MSM)-based solutions and Eringen elasticity theory are applied to demonstrate the aforementioned effects on a narrow clamped-clamped (CC) nanotube in detail. The approximate analytical solution is verified by numerical integration methods and a good agreement between the approximate analytical and numerical results is observed. The effect of all important parameters such as local and nonlocal viscosity damping, nonlinear damping coefficient, linear and nonlinear stiffness of the elastic medium due to changes in amplitude vibration of the magnetic field (AVMF) and displacement responses (DR) have been investigated. The original research proposed in this paper may enable the systematic study of nonlinear damping in nanomechanical oscillators, which may help to reveal the underlying physical mechanism.

Experiments of ablation characteristics for different nozzle materials and transient simulations on thermochemical erosion in hybrid rocket motors

This paper focuses on investigating ablation characteristics of different nozzle materials in hybrid rocket motors by firing tests and numerical simulations. Hybrid rocket nozzles with different ablation materials are designed and manufactured. Four firing tests with working time of 40 s are conducted, and 90% hydrogen peroxide and polyethylene are adopted. The test results indicate that erosion rates of T705 graphite, whole felt C/C composite, axial rod braided C/C composite, and carbon/ceramic composite are 0.045 mm/s, 0.022 mm/s, 0.03 mm/s, and 0.01 mm/s. Circumferentially uneven ablation is found in the nozzle throat of T705 graphite and C/C composite, and this is mainly due to asymmetric oxidizer injection, asymmetric combustion, and uneven material properties. Transient numerical simulations of 40 s on nozzle thermochemical erosion are carried out, and the regression process of fuel wall and nozzle wall is solved by a dynamic grid technique. The error of average throat erosion rate between simulation results and test results is only 1.82%. The evolution process of nozzle profile and flow field structure are exhibited, and coupling effects between the erosion rate and nozzle profile are obtained. Simulation results show that as the working time increases, protrusions and pits appear on the nozzle inner wall and gradually extend. The temperature of nozzle wall and nozzle erosion rate on the windward side is higher, while they are lower on the leeward side. Nozzle throat erosion rate history is divided into four stages, and time nonlinear characteristics of the throat erosion rate are revealed.

On nonlinear damping effects with nonlinear temperature-dependent properties for an axial thermo-viscoelastic rod

The present manuscript develops a new axisymmetric model of thermo-viscoelastic rods to account for uniform temperature effects and nonlinear terms, which are induced by Kelvin–Voigt damping. A fundamental relationship between the damping of viscoelastic material and nonlinear geometry are researched through the application of Galerkin and multiple scale (MS) methods to the new model. Then, the MSM-based solutions are confirmed with a numerical integration method, and a good agreement between the approximate analytical and numerical results is observed. Free axial vibrations based on the standard linear solid model in uniform thermal rises with nonlinear material properties as a function of temperature is considered. The temperature of the viscoelastic rod remains constant under conditions of uniform temperature rise. Studying the behavior of the dynamic system in the presence of uniform temperatures increases the effect of nonlinear damping on its vibration behavior. Approximate analytical results are presented for use as a reference point in future analysis of nonlinear thermo-viscoelastic rods with a weak hardening system. Also, the results of this research can be useful and practical for finding the modal damping ratio of the system as well as the dynamic analysis of damping in the presence of thermal environment.

Biomechanical comparison of different rod-to-rod connectors to a conventional titanium- and cobalt chromium posterior spinal fixation system

IntroductionSeveral types of rod-to-rod connectors are available for the extension of spinal fixation systems. However, scientific literature regarding the mechanical performance of different rod-to-rod connector systems is lacking. Research questionThe goal of this study was to evaluate the mechanical characteristics of axial and lateral rod connectors in comparison to a conventional pedicle screw rod (titanium and cobalt chromium) construct. Material and methodSix types of instrumentations were investigated in a standardized test model to quantify the mechanical differences: 1: titanium rod; 2: titanium rod with axial connector; 3: titanium rod with lateral connector; 4: cobalt chromium rod; 5: cobalt chromium rod with axial connector; 6: cobalt chromium rod with lateral connector. All groups were tested in static compression, static torsion and dynamic compression and statistically compared regarding failure load and stiffness. ResultsIn static compression loading, the use of connectors increased the construct stiffness, but unaffected the yield load. The use of a cobalt chromium rod significantly increased by approximately 40% the yield load and stiffness in comparison to the titanium rod configurations. Under dynamic compression, a similar or higher fatigue strength for all tested groups in comparison to the titanium rod configuration was evaluated, with the exception of titanium rod with axial connector. ConclusionBiomechanically, using rod connectors is a secure way for the extension of a construct and is mechanically equal to a conventional screw rod construct. However, in clinical use, attention should be paid regarding placement of the connectors at high loaded areas.

Mechanical Analysis and Validation of the Prototype of Nb3Sn Superconducting Magnet Structure With Dummy Coils for FECR Ion Source

The Fourth-generation Electron Cyclotron Resonance (ECR) ion source (FECR) Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconducting magnet is being developed by Institute of Modern Physics (IMP), Chinese Academy of Sciences. In order to reduce the risk of development and address key technical challenges, a half-length prototype is designed. The prototype consists of six sextupole coils and two solenoid coils. To validate the assembly and loading procedures, the structure was assembled with dummy sextupole coils (Al 6061 cylinder) and dummy solenoid coils (extend solenoid stainless-steel formers) that replaced the brittle Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn coils, then cooled-down to 77 K with liquid nitrogen and warmed up. The dummy coils are different from Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn coils, the mechanical behavior of the structure in each step is analyzed with finite element software ANSYS. The numerical analysis model must be cross-checked with the tests and validate it. The evolution of the mechanical behavior was monitored via strain gauges located on different components of the structure (Al shell, dummy sextupole coils, and axial rods). We focus on the expected stresses within the structure after assembly and pre-loading, cool down, warm up and thermal cycle. The expected stresses were determined from the 3D finite element model (FEM) of the structure. Some low-temperature strain gauges, were used to monitor strain of the structure during the pre-load control performance and thermal cycle process. A comparison of the 3D model strain/stress predictions with the strain gauge data measurements is made. The coherence between the predicted contact pressure/strain/stresses with Fuji paper and the experimental gauge measurements will validate the FEM model of the structure. Once robust finite element analysis (FEA) numerical results are available, we can estimate and improve the final results of the real assembly with Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn coils. So as to realize the stress management of the magnet.

Double restabilization and design of force–displacement response of the extensible elastica with movable constraints

A highly deformable rod, modelled as the extensible elastica, is connected to a movable clamp at one end and to a pin sliding along a frictionless curved profile at the other. Bifurcation analysis shows that axial compliance provides a stabilizing effect in compression, but unstabilizing in tension. Moreover, with varying the contraint’s curvature at the origin and the axial vs bending rod’s stiffness, in addition to possible buckling in tension, the structure displays none, two, or even four bifurcation loads, the last two associated only to the first buckling mode in compression. Therefore, the straight configuration may lose and recover stability one or two times, thus evidencing single and double restabilization, a feature never observed before. By means of the closed-form solution for the extensible elastica, the quasi-static behaviour of the structure is analytically described under large rotations and axial strain. The presented solution is exploited, together with an ad hoc developed optimization algorithm, to design the shape of the constraint’s profile necessary to obtain a desired force–displacement curve, so to realize a force-limiter or a mechanical device capable of delivering a complex force response upon application of a continuous displacement in both positive and negative direction.

Trace-level detection and classifications of pentaerythritol tetranitrate via geometrically optimized film-based Au/ZnO SERS sensors

This work has explored the scalable, multi-batch fabrication process of the Au-decorated ZnO nanorod (NR) SERS sensors with five designed geometries (A to E), based on the hydrothermally synthesized ZnO NR templates prepared at different reaction time (3.0, 4.5, 6.0, 8.0, and 10.0 h). Each sample geometry was fabricated for three batches. The physical morphologies of the templates and the SERS substrates were examined by various techniques, whose results demonstrated the variations in their physical dimensions. The aggregations of the nanorods into several clusters at the tips were clearly observed. The material compositions were verified with ZnO as the inner axial rod, and the Au element enveloping the nanorod tip. The finite element method (FEM) simulations predicted the generated E-field at 3.32 V/m obtained from the sample geometry B (4.5 h). The SERS performance were thoroughly investigated with the pentaerythritol tetranitrate (PETN) substance obtained from three different sources, each with serial dilution from 100 mg/ml to 0.1 µg/ml. The analyte solution was drop-casted on the SERS sensors, on which the hyperspectral Raman-mapping measurements were performed. With principal component analysis (PCA) and linear discriminant analysis (LDA), the results showed that the most optimal SERS sensors yielded distinguishable clusters of the different PETN sources, with the classification accuracy at 73.47 ± 0.64%. The proposed SERS sensors exhibited the optimal performance at 10−4 g/ml, the limit of detection (LOD) at 10−7 g/ml with the enhancement factor (EF) of 3.01 × 106, which therefore allowed potential implementation towards the trace detection and classifications of the PETN substance.

Novel size-dependent finite element formulation for modal analysis of cracked nanorods

It is a remarkable engineering problem how possible structural damages in nano/micro scaled mechanical elements affect the working performance and mechanical behavior of nano/micro-electro-mechanical system (NEMS/MEMS) organizations. There are various nano/micro-scale mechanical elements that can be modelled as one-dimensional and continuous systems in NEMS/MEMS organizations. With this motivation, the free vibration analysis of nano scaled axial rods with a single crack is examined by employing the nonlocal finite element formulation for the first time in the literature in this study. Firstly, the differential equation of nonlocal vibration of nanorods is presented for a single crack. Next, a nonlocal finite element formulation developed for the case of crack is proposed. The local and nonlocal nondimensional frequency parameters of cracked nanorods are compared with some studies in the literature. Additionally, nondimensional frequencies of nanorods are presented with several tables and graphics according to different parameters such as nonlocal parameter, mode number, crack intensity and crack location. Detailed discussions of the numerical results are given, and the conclusions deduced from these discussions are summarized.

Air plasma ablation/erosion test for 4D C/C composites used in the throat of solid rocket motor

A small-scale plasma ablation facility was employed to test the four-directional carbon/carbon (4D C/C) composites under high enthalpy multi-phase jet condition for ablation/erosion performance evaluation with the ablation flow field studied via computational fluid dynamics (CFD). The various ablation rates, ablation behavior and microstructure of the C/C specimens were investigated. The overall mass ablation rate was 0.05715 g·s−1 with 0.05550 mm·s−1and 0.01794 mm·s−1 axial linear ablation rate of inner and outer walls. In the radial direction, the linear ablation rates were 0.07794 and 0.00517 mm·s−1 for the inner and external diameter respectively. Ablation changes the inner wall of the annular specimen into an inverted horn shape, while the edge near the jet becomes rounded corners after the plasma procedure. The interface between the axial carbon rod and the matrix has visible ring fractures. Alumina particles are lodged in cracks and holes as a result of multiphase flow scouring. The regression rate of the composites can be considerably accelerated by particle erosion and the existence of inherent defects. The specimen ablation of top surface and inner wall is attributed to the coupling of the heterogeneous reaction and multiphase erosion. On the back wall of specimen, the regression is mainly caused by thermochemical ablation.

Experimental and numerical study of a split cathode fed relativistic magnetron

The relativistic magnetron is one of the most efficient high power microwave (HPM) sources but pulse shortening, the result of explosive cathode plasma's radial expansion toward the anode, makes it impractical because the HPM pulse terminates much earlier than the applied voltage. We present experimental results of the operation of a relativistic magnetron fed by a split cathode. A split cathode [Leopold et al., Phys. Plasmas 27, 103102 (2020)] consists of a cathode placed upstream and outside the anode, connected by an axial rod to a reflector (a transverse conducting circular plate) placed downstream from the anode. The electron charge, emitted by an annular explosive cathode emitter, accumulates in the space between the cathode and the reflector and at the same time, screens the rod from explosive plasma formation. This accumulated space charge serves as the electron source for the magnetron. The explosive plasma developing on the emitter remains outside the magnetron and does not propagate into the anode while it operates. We compare the performance of the magnetron operating with a standard explosive emitting solid carbon cathode to that with a split cathode. The experiments demonstrate that whereas for the solid cathode, the microwave pulse developing in the magnetron suffers from pulse shortening, with a split cathode, the pulse survives as long as the amplitude of the applied voltage is sufficient for the magnetron's operation. We support the experiment by particle-in-cell simulations.

Analysis and Improvement of Oblique Shear Phenomenon of Direct Shear Apparatus

Direct shear test is an important method to test the shear strength of soil. But the phenomenon of “oblique shear” often appears in the process of test, the soil sample subjected to eccentric pressure and uneven stress distribution, which affect the stability and accuracy of the test. This paper, starts from the construction of the direct shear apparatus, found that the relative displacement between the upper shear box and the axial pressure rod, is one important cause of “oblique shear”. Set the steel ring between the lower shear box and the push rod, dose not affect the shear force measurement and can completely fix the upper shear box. There is no relative displacement between the upper shear box and the rod used to apply axial pressure after improvement, and no the phenomenon of “oblique shear”. The experimental results are more stable and the coefficient of variation is smaller. The improvement scheme of the direct shear apparatus is simple, the improvement effect is obvious, and the stability and accuracy of the direct shear test are improved.

Study on Mechanical Properties and Failure Mechanism of Axial Braided C/C Composite

In order to study the mechanical properties and failure mechanism of the axial braided C/C composites, the microscopic and macroscopic mechanical properties of the composite were investigated. In view of the size effect of the samples, the properties of the samples with different thickness were tested. The strain during loading was measured by optical method, and the failure morphology was observed by SEM. The changing characteristics of stress-strain curve were analyzed, and the failure characteristics of materials and failure mechanism under various loads were obtained. It was found that brittle fracture was observed during the tensile process of axial braided C/C composites, and the main failure forms were fiber rod pulling and partial fiber rod breaking in the axial direction. Radial failure was mainly in the form of fiber bundle fracture and crack stratification propagation. When compressed, the material exhibited pseudoplastic characteristics. The radial compression sample was cut along a 45-degree bevel. The axial compression curve was in the form of double fold, the axial fiber rod was unstable, and the transverse fiber bundle was cut. During in-plane shearing, the axial fracture was brittle and the fiber rod was cut. The radial direction showed the fracture and pulling of the fiber bundle, and the material had the characteristics of pseudoplasticity. The research methods and results in this paper could provide important references for the optimization and rational application of C/C composite materials.