Axial Load Research Articles (Page 1)

Accurate prediction of runway pavement conditions is critical for aviation safety and maintenance planning. This study presents a Hierarchical Bayesian Joint Model with latent variables to simultaneously forecast key performance metrics—the International Roughness Index (IRI) and Surface Macrotexture Depth (SMTD)—while explicitly accounting for measurement uncertainties. The proposed model incorporates nonlinear quadratic relationships among axial loads, SMTD, and IRI, effectively capturing both direct and indirect load effects. Model performance was rigorously evaluated through a stratified five-fold cross-validation, achieving mean absolute errors as low as 0.98 for IRI and 0.88 for SMTD, outperforming traditional methods by approximately 15%. Posterior diagnostics confirmed robust convergence and accurate uncertainty quantification. Overall, the hierarchical Bayesian model demonstrated superior predictive accuracy, highlighting its practical utility for data-driven pavement management decisions.

Intervertebral disc degeneration is a primary cause of chronic low back pain (LBP), which affects people worldwide and leads to disability. Intervertebral discs (IVDs) are a mechanically dynamic tissue where the annulus fibrosus (AF) absorbs axial load, supports spinal motions, and resists disc deformation and degeneration. Axial stress applied to the disc translates into interlamellar radial stress, potentially leading to AF tears and nucleus pulposus (NP) extrusion, especially in the lumbar region. We developed a hyaluronan-coated type-I collagen (Col-I HA) hydrogel scaffold to promote AF tissue repair and mechanically stabilize IVD. These scaffolds exhibit high tensile strength (∼5 MPa), comparable to that of the annulus fibrosus, which is attributed to the alignment of collagen fibrils with preserved secondary structures. The developed scaffolds demonstrated high cell viability and alignment of isolated primary AF cells and rat bone marrow stem cells (RBMSCs) along the collagen fibrils. Notably, primary AF cells and RBMSCs cultured on the Col-I HA hydrogel scaffold showed high expression of native ECM markers, such as collagen-I and aggrecan, reflecting the regenerative potential of the developed scaffold. Elevated levels of CD146 and Acta2 indicated a shift toward a contractile phenotype in both cell types. Ex vivo and in vivo studies using annulotomy-induced rat coccygeal disc model following Col-I HA implantation demonstrated mechanical restoration of IVD when investigated for uniaxial compressive strength. Histological and immunohistochemical analyses revealed significant collagen and glycosaminoglycan (GAG) deposition in Col-I HA-treated discs compared with the untreated AF-defective disc. Interestingly, fibrotic changes were observed in the Col-I HA-treated groups, as confirmed by the upregulation of profibrotic markers, including fibronectin, transforming growth factor, and α-smooth muscle actin, in the in vivo model. Thus, the Col-I HA hydrogel scaffold exhibited fibrotic changes in the AF and contributed to IVD stabilization.

Abstract It has been demonstrated that steel sucker rod strings are susceptible to failure during the process of oil production. Such failure can be attributed to two primary factors: corrosion and insufficient strength. Conversely, carbon fiber sucker rods have gained a notable presence in ultra-deep wells and corrosive wells, a testament to their exceptional strength and corrosion resistance. During operation, composite sucker rods composed of carbon fiber and steel are subject to viscoelastic fluid and axial movement excitation at the suspension point, in addition to pump-end loads. This combination of factors leads to the development of highly complex deformation and stress patterns.This paper introduces the concept of the local hydraulic damping coefficient and considers axial motion, viscoelastic fluid force, and non-uniform axial load. The microelement method is employed to derive the dynamic equation of the carbon fiber combined pumping rod. The establishment of a dynamic model of the carbon fiber combined pumping rod and column is predicated on two fundamental equations: the longitudinal vibration equation of the pumping machine's suspension point and the plunger liquid load law. The differential method was employed to solve the model and ascertain the load-change mechanism of the suspension point, the concentrated axial load at the pump end, and the axial distributed load of the combined pumping rod and column. The findings of the study indicate that altering the diameter of the sucker rod pump, the stroke times, and the stroke length of the pumping unit causes significant changes in the concentrated load at the pump end, making the sucker rod string prone to buckling. The axial load distribution along the carbon fiber composite sucker rod string fluctuates with time and rod length. Increased stroke rates result in greater axial load distribution along the rod string, thereby increasing the likelihood of uneven wear on the sucker rods.

3D printing is a cost-effective manufacturing approach that offers several advantages for health care delivery, including rapid prototyping, precise customization to patient anatomy and user specifications, and the capability to produce implants directly at the point of care. The purpose of this study was to test whether 3D-printed carbon fiber-reinforced polyetheretherketone (CF-PEEK) one-third tubular plates are statistically equivalent, within prespecified margins, to stainless steel plates in simulated early weightbearing and torsion. Carbon fiber-reinforced polyetheretherketone one-third tubular plates were designed and printed using Fused Deposition Modeling printers by study authors. These were compared to traditionally manufactured plates using 4-point bend tests. A cadaveric biomechanical comparison between fractures stabilized using 3D-printed plates and traditional manufactured plates was performed. Matched-pairs specimens underwent axial cyclic loading and torsional load to failure. Ten matched paired specimens underwent mechanical testing. All specimens survived 100 000 cycles loaded to 875 N. Torque at failure did not significantly differ between groups (P = .14). During torsional load to failure, all 10 specimens (100%) with the traditional plate failed because of screw pullout. Five specimens (50%) with the 3D plate failed because of screw pullout and 5 (50%) failed because of plate fracture. Fifteen plates (five 3D, five 3D post autoclave, 5 traditional) underwent 4-point bending test. Stiffness was significantly lower in the 3D plates (P < .0001). The coefficient of variation was 0.06 for the 3D-printed plates and 0.01 for the traditional manufactured plates, demonstrating high consistency within groups. In conclusion, this cadaveric study found that nonsterilized CF-PEEK plates demonstrated statistically equivalent displacement and torque at failure to stainless steel plates. However, they exhibited reduced stiffness and a higher incidence of plate fracture. Additionally, autoclave sterilization had a significant impact on the mechanical properties of the CF-PEEK plates. These findings underscore the need for additional biomechanical and clinical studies to assess the performance of 3D-printed implants and to refine sterilization protocols. These results suggest that constructs using 3D-printed CF-PEEK plates can perform statistically equivalently (within prespecified margins) to stainless steel constructs in simulated early weightbearing and torsion, despite different material properties. The impact of sterilization, however, must be considered, and alternatives to autoclaving are recommended.

The gyroscopic effect has significant impacts on the stability, dynamic behavior, and vibration characteristics of high-speed rotating systems. A floating offshore vertical axis wind turbine (FOVWT) exhibits gyroscope-like motions under combined wind–wave–current conditions; the attitude angles of the shaft connected to the platform change continuously in space, making the overall system’s gyroscopic effect more pronounced. From a geometric perspective, this study investigates a method to suppress the gyroscopic effect of floating offshore vertical axis wind turbines: replacing the conventional single-Φ rotor with a stagger-mounted double-layer double-Φ rotor. This configuration exploits the phase difference in circumferential (i.e., 360° around the rotor) aerodynamic loads experienced by the upper and lower rotors; the superposition of these loads ultimately reduces the platform’s pitch response. This study adopts computational fluid dynamics (CFD) for numerical simulations. First, using the NREL 5-MW OC4 floating horizontal axis wind turbine (FOHWT) platform as the research object, we computed the platform’s motion responses under different environmental conditions and verified the effectiveness of the numerical method through comparison with published literature data. Then, under the same marine environment, we compared the motion responses of the conventional single-Φ turbine and double-Φ turbines with different misalignment angles. The results show that modifying the Φ-type rotor configuration can effectively reduce the axial load on the rotor and enhance system stability. As the rotor misalignment angle increases from 15° to 90°, the pitch motion amplitude decreases from 20.6% to 11.8%, while the overall turbine power is only slightly reduced.

Compared to hot - rolled steel sections, cold - formed steel sections are more susceptible to instabilities. Under compressive loading, several global, distortional, and local buckling instability modes are expected to manifest. This paper summarizes results of an experimental program carried out at the National Center of Applied Research on Earthquake Engineering Laboratory (CGS) in ALGERIA to investigate the behavior up to failure of composite wood cold formed steel stud under cyclic axial loading, in which a wood core is incorporated inside the cold formed steel C stud subjected to axial cyclic loading which was compared with simple cold formed steel C stud. Six full scale columns with both ends fixed were tested, three cold formed steel C stud (600s200 - 68) and three with the same C sections reinforced with wood. Two monotonic axial concentric loading tests (one compression and one tension) and one cyclic axial loading test with different loading rate were performed on both cold - formed steel (CFS) columns and Wood CFS columns. The cyclic loading protocol was adapted from FEMA 461 with initial displacement obtained from the monotonic tests. The results showed that the local deformations (local buckling) were less noticeable for the wood CFS columns. It was also observed that, the degradation of resistance, rigidity and the total hysteretic energy dissipated were more important for composite columns.

The mechanical response and failure behavior of high-pressure frozen ice are essential to the technological progress in drilling thick polar ice sheets, but current research primarily focuses on non-pressure-frozen ice. In this paper, ice specimens with a cylindrical geometry were fabricated at −20 °C, applying freezing pressures across a range of 10 to 40 MPa with a 10 MPa interval. Their mechanical properties were investigated through triaxial compression tests under axial loading conditions and were compared with the results obtained at −10 °C. The results indicate that, with increasing freezing pressure, the samples transitioned from a failure state of interlaced cracking to a highly transparent state. The failure behavior observed in the specimens was characterized as ductile, as evidenced by the deviatoric stress–axial strain relationships. Moreover, the peak deviatoric stress exhibited a non-monotonic dependence on freezing pressure, with an initial rise from 9.59 MPa at 10 MPa to a peak of 14.37 MPa at 30 MPa and a subsequent decline to 10.12 MPa at 40 MPa. All specimens reached a relatively stable residual state at 5% axial strain, with residual deviatoric stresses ranging from 4.13 to 5.71 MPa. A reduction in freezing temperature from −10 °C to −20 °C can effectively enhance both the peak deviatoric stress and the residual stress of high-pressure frozen ice under triaxial shear conditions. All peak tangent modulus values, ranging from 1.61 to 2.93 GPa with an average of 2.2 GPa, were observed within 0.7% axial strain and exhibited mild fluctuations with increasing freezing pressure. These findings provide a more robust mechanical foundation for drilling research and operations in extremely thick polar ice caps.

This study presents a numerical investigation into the structural behavior of a pile-in-pile (PIP) slip joint utilizing square hollow section (SHS) members, with a comparative assessment against conventional circular hollow sections (CHSs). A comprehensive finite element model was developed and validated against published CHS experimental results to evaluate key performance indicators, including stress distribution, buckling behavior, and load-carrying capacity under pure bending, axial compression, and diagonal lateral loads. The analysis revealed that SHS joints demonstrated distinct stress concentration patterns and higher capacity under axial compression, whereas CHS joints provided superior performance under bending due to their geometric symmetry. However, SHS corners were more vulnerable under diagonal loading, exhibiting localized buckling at relatively lower loads. These structural weaknesses can be mitigated through design improvements, such as increased wall thickness or corner strengthening. The findings highlight that while SHSs introduce certain vulnerabilities compared to CHSs, they also offer advantages in axial load resistance, supporting their potential as a viable alternative for offshore wind foundation connections.

Uniaxial compression testing provides essential mechanical property characterization for intact rock specimens. The accuracy of specimen preparation critically affects compression test results through end-surface geometry deviations: parallelism, perpendicularity, and diameter tolerance. Specimen end-surface parallelism is affected by surface irregularities (e.g., protrusions, warping), whereas perpendicularity deviations indicate angular misalignment of the specimen with the loading axis. This study develops a 3D uniaxial compression model using RFPA3D, with rigid loading plates to simulate realistic boundary conditions. Three typical end-surface defects are modeled: protrusions (central/eccentric), grooves, and unilateral warping. Specimens with varying tilt angles are generated to evaluate perpendicularity deviations. Simulation results reveal that central end-surface protrusions induce: (1) localized stress concentration, which forms a dense core, and (2) pronounced wedging failure when protrusion height exceeds critical thresholds. Eccentric protrusions trigger characteristic shear failure modes, while unilateral warping causes localized failure through stress concentration at the deformed region. Importantly, end-surface grooves substantially alter stress distributions, generating bilateral stress concentration zones when groove width exceeds critical dimensions.

Abstract In the present study a metastable austenitic stainless steel X2CrMnNi16-7–4.5 was investigated. The alloy composition was adjusted by mixing steel powder X2CrMnNi16-7–9 and steel powder X2CrMnNi16-7–3, whereby the first steel exhibits a primary-austenitic and the latter one a primary-ferritic solidification of the melt, in order to achieve a fine-grained, predominantly austenitic microstructure. After mixing of the powder blend the material was subsequently processed by in situ alloying during powder bed fusion electron beam melting (PBF-EB/M), using two different build parameter sets. The study demonstrates how powder blending and in situ alloying can be used to tailor microstructural features like grain size, texture and phase composition in PBF-EB/M processing by changing the chemical composition of an alloy. The microstructure and phase composition of manufactured specimens were examined by different techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD) and measurements of ferromagnetic phase content. The steel was predominantly austenitic and exhibited a fine-grained microstructure for one of the build parameter sets, with a slight &lt; 011 &gt; texture in build direction (BD) after the PBF-EB/M process. Mechanical properties of alloy X2CrMnNi16-7–4.5 were characterized by tensile as well as low cycle fatigue (LCF) tests. In tensile tests the material possesses excellent mechanical properties due to the occurrence of the TRIP (TRansformation-Induced Plasticity) effect under loading, whereby the orientation of the loading axis (LA) relative to the build direction plays a detrimental role. Fatigue tests revealed that surface polishing did not show any improvement in fatigue lifetime compared to the as-built specimens with a natural surface, which was attributed to the presence of numerous inclusions and lack of fusion (LOF) defects.

Wire rope joints are critical components requiring detailed mechanical analysis. This study investigates the stress/strain characteristics at the joint root under axial impact and combined tension-bending loads. A mathematical model was derived from the rope’s spatial structure, enabling the construction of 3D simulation and finite element models. Explicit dynamic analysis revealed distinct stress evolution patterns. Under axial impact, the joint root wires experience instantaneous peak stress causing core, inner, and outer wire yielding, though stress rapidly decreases and stabilizes. During stable loading, maximum stress (67% of impact peak) occurs on the joint root’s secondary outer wire. Under combined tension-bending, maximum stress dynamically shifts to the tension-side secondary outer wire at the joint root. Critically, both loading conditions identify the joint root’s secondary outer wire as the primary danger zone, with combined tension-bending producing a maximum local stress 1.04 times higher than axial impact. These findings highlight consistent failure locations and quantify relative stress magnitudes under complex loading.

When drilling inclined and horizontal sections, a significant part of the drill string is in a compressed state which leads to a loss of stability and longitudinal bending. Modeling of the stress–strain state (SSS) of the drill string (DS), including prediction of its stability loss, is carried out using modern software packages; the basis of the software’s mathematical apparatus and algorithms is represented by deterministic statically defined formulae and equations. At the same time, a number of factors such as the friction of the drill string against the borehole wall, the presence of tool joints, drill string dynamic operating conditions, and the uncertainty of the position of the borehole in space cast doubt on the accuracy of the calculations and the reliability of the predictive models. This paper attempts to refine the actual behavior of the drill string in critical and post-critical conditions. To study the influence of dynamic conditions in the well on changes in the SSS of the DS due to its buckling, the following initial data were used: a drill pipe with an outer diameter of 88.9 mm and tool joints causing pipe deflection under gravitational acceleration of 9.81 m/s2 placed in a horizontal wellbore with a diameter of 152.4 mm; axial vibrations with an amplitude of variable force of 15–80 kN and a frequency of 1–35 Hz; lateral vibrations with an amplitude of variable impact of 0.5–1.5 g and a frequency of 1–35 Hz; and an increasing axial load of up to 500 kN. A series of experiments are conducted with or without friction of the drill string against the wellbore walls. The results of computational experiments indicate a stabilizing effect of friction forces. It should be noted that the distance between tool joints and their diametrical ratio to the borehole, taking into account gravitational acceleration, has a stabilizing effect due to the formation of additional contact force and bending stresses. It was established that drill string vibrations may either provide a stabilizing effect or lead to a loss of stability, depending on the combination of their frequency and vibration type, as well as the amplitude of variable loading. In the experiments without friction, the range of critical loads under vibration varied from 85 to &gt;500 kN, compared to 268 kN as obtained in the reference experiment without vibrations. In the presence of friction, the range was 150 to &gt;500 kN, while in the reference experiment without vibrations, no buckling was observed. Based on the results of this study, it is proposed to monitor the deformation rate of the string during loading as a criterion for identifying buckling in the DS stress–strain state monitoring system.

This research presents an experimental investigation on the compressive behavior of fiber reinforced polymer-confined concrete-filled steel tubes (FRP-CFSTs). The study evaluated 72 specimens, including CFST and FRP-CFST columns, with varying numbers of FRP layer (0–3), steel tube thickness (1.8 to 3.8 mm), and nominal concrete strength (20, 30, 40 MPa). Concrete mixes enhanced with polypropylene fibers and silica fume were used. Material properties for the infill concrete, steel tube yield strength (307 MPa), and CFRP tensile parameters (ultimate strain 2.1%, tensile strength 4900 MPa) were determined. The test specimens were wrapped with CFRP sheets using a wet lay-up process and subjected to axial compression through a 4000-kN capacity machine. The load–deformation behavior until failure, which typically occurred due to FRP rupture from lateral concrete expansion, was recorded. Results revealed that FRP confinement increased the ultimate axial load capacity of CFST columns and enhanced ductility with improvements correlating positively with the number of CFRP layers. Steel tube thickness contributed to an increase in stiffness and load capacity by roughly 15–25%. Concrete mixes incorporating polypropylene fibers and silica fume demonstrated superior performance compared to conventional mixes by reducing brittleness and improving tensile and flexural strengths. These quantitative findings demonstrate the significant influence of FRP confinement and concrete mix design on the enhancing strength, stiffness, and ductility of CFST columns, supported by rigorous experimental characterization and systematic analysis of their composite behavior.

In precast concrete shear wall structures, the joints formed during the vertical connection of precast units are referred to as the “horizontal joint”. Serving as vertical connection nodes in this structure system, the construction quality of theses horizontal joints significantly influences the structural integrity. To investigate the influence of horizontal joint quality defects on the mechanical behaviour of precast concrete shear walls, three precast concrete shear wall specimens with quality defects in different regions and three control specimens were designed. Quasi-static tests under a constant axial load were conducted to investigate the effects of defect area, location and other factors on the mechanical behaviour of the walls. Results demonstrate that the quality defects in horizontal joints significantly affect the mechanical behaviour of precast concrete shear walls. When the ratio of the quality defect area to the cross-sectional area of the boundary member reaches 100%, the yield load and peak load of the precast concrete shear wall decrease by 13% and 20%, respectively. Additionally, the structural stiffness exhibited a 13% degradation at a drift angle of 1/1000. Although the failure mode remains largely unchanged, yielding of longitudinal reinforcement in the boundary members is observed. Moreover, as the proportion of the quality defect area to the cross-sectional area decreases, its adverse effects on the mechanical behaviour of the precast concrete shear wall gradually diminish. The established numerical analysis model is shown to be reasonable and reliable. When the defective area of the horizontal joints is less than 25% of the total cross-sectional area, the quality defects essentially have no influence on the mechanical behaviour of the precast concrete shear walls.

Experimental and theoretical investigation of low-shrinkage alkali-activated materials permanent formwork reinforced concrete prisms under axial load

Influence of axial prestress and loading rate on dynamic fracture of pre-faulted granite

Experimental and numerical investigation on reinforced CFSST columns under axial compressive loading

Prediction of expected maximum moment strength for reinforced concrete columns with normal and high-strength materials under varying axial load ratios

Design and experimental demonstration of newly developed composite overwrapped pressure vessels with axial load members for fuel cell vehicles

Choosing the appropriate implants for reconstruction in revision TKA is essential for long-term fixation. While cones and augments are routinely utilized to address tibial defects, the effect of augment location and size on the biomechanical stability of revision TKA constructs and the indications for the use of metaphyseal cones are not known. Is the risk of cement-implant debonding of revision TKA constructs impacted by the thickness and location (medial versus bicompartmental) of tibial augments and the presence of metaphyseal cones during (1) a demanding daily activity like stair ascent and (2) torsional loads? Under institutional review board approval, we developed patient-specific finite-element models of revision TKA from four patients (three males and one female, ages 50 to 80 years, BMI 27 to 37 kg/m 2 ) who underwent two-stage revision and had a CT scan with no metal artifact after first-stage implant removal. For each patient, we created 5-mm, 10-mm, and 15-mm-thick medial and bicompartmental uncontained defects. We considered two situations for the metaphysis: using a metaphyseal cementless cone into which the implant was cemented or using only cement to fill the metaphyseal cavity. To answer our first question, we conducted finite-element simulations of the immediate postoperative loading scenario representative of stair ascent, while to answer our second research question, we considered an idealized torsional test consisting of 100 N of axial load and twice the axial moment experienced at the same instant of stair ascent. We calculated the risk of cement-implant debonding from an interfacial failure function (calculated as a function of the normal and shear stresses at the cement-implant interface) wherein values of interfacial failure ≥ 1 indicate debonding. Our primary outcome was the cement-implant interface area with ≥ 10% risk of debonding, which we considered to be the interface area with greater than minimal risk of debonding. During stair ascent, we computed a decrease of the cement-implant interface area with greater than minimal risk of debonding (that is, ≥ 10% risk of debonding) with medial uncontained defects (median [IQR] 2.6% [1.4% to 3.7%] with 15-mm augment) but not with bicompartmental defects (5.2% [3.7% to 5.3%]) compared with the scenario with no uncontained defect (5.2% [3.9% to 5.9%]). Compared with using a metaphyseal cone, using cement alone in the metaphysis increased the interfacial area with greater than minimal risk of debonding, reaching a median (IQR) of 13.8% (11.4% to 14.3%) with a 15-mm bicompartmental defect. Under the torsional load scenario, the increase in the area with greater than minimal risk of debonding was small for medial defects, from a median (IQR) of 4.3% (2.5% to 5.3%) to 4.9% (3.9% to 6.2%) when using a metaphyseal cone and from 7.0% (4.0% to 9.5%) to 7.2% (6.1% to 9.8%) when only using cement in the metaphysis. However, the area at risk of failure of bicompartmental defects under torsional loads reached 23% when using a metaphyseal cone and 52% when using only cement in the metaphysis. The size of bicompartmental uncontained defects treated with a bicompartmental augment (a full block) negatively affected the overall construct stability in our finite-element model. However, medial defects of the same size did not negatively influence the stability of the construct when addressed with an augment perfectly contacting the bone. In our computational finite-element model, using metaphyseal cones increased the stability of the revision TKA construct. Our finite-element results suggest that medial augments have little impact on the stability of revision TKA constructs, but clinicians may want to combine bicompartmental augments with cones for increased stability of revision TKA constructs.