Multidirectional Loading Research Articles

A multi-axial bounding surface p-y model with application in analyzing pile responses under multi-directional lateral cycling

Multi-directional cyclic loads, as often experienced by piles supporting offshore wind turbines (OWTs), could reduce global soil-pile stiffness, and jeopardize the serviceability of OWTs. Most of the existing p-y models focus on uni-directional soil-pile interaction, with a few multi-directional models developed at the cost of additional parameters that require unusual tests for multi-directional cycling. This study presents a multi-directional bounding-surface based cyclic model for lateral soil-pile interaction in both sand and clay. It can model multi-directional cyclic hysteresis and shakedown using only six parameters, without requiring extra parameters and tests for multi-directional cycling. This is achieved by introducing several uni-directionally loaded springs around the pile at each depth. The cyclic p-y relation for multi-directional loading is derived from that for uni-directional loading, by solving equations on equality of work required for the two models under a given displacement increment. The proposed model is validated against experimental results on piles under uni- and multi-directional cycling with various load- and displacement-controlled paths. It is found that following change of loading direction, the pile displacement accumulation is not only limited to the new loading direction, but includes transverse cycling towards the direction of least soil stiffness softened by the recent loading directions. The transverse cycling causes an additional reduction in the global soil-pile stiffness, facilitating the accumulation of lateral pile displacement.

Multidirectional Vibroseis Shaking and Controlled Blasting to Determine the Dynamic In Situ Response of a Low-Plasticity Silt Deposit

In this paper, efforts to characterize and compare the full-scale in situ three-dimensional (3D) dynamic response of a low-plasticity silt deposit to multidirectional loading from two different sources, a vibroseis shaker named T-Rex and controlled blasting, are presented. Horizontal vibroseis shaking at a frequency, f, of 10 Hz, produced dynamic responses in the silt that ranged from linear-elastic to nonlinear-inelastic, inducing maximum equivalent direct simple shear (DSS) shear strains, γDSS,max, up to 0.15% and residual excess pore pressure ratios, ru,r, of 14.1%. Blast-induced shear waves with predominant frequencies ranging from 9.6 to 14.6 Hz excited nonlinear-elastic and nonlinear-inelastic responses in the silt deposit, with γDSS,max of 1.14% and maximum ru,r of 61%. Importantly, these responses were observed to be minimally influenced by high frequency compression waves. Multidirectional loading, and excess pore pressure, ue, migration and impedance were identified as the predominant factors for achieving the large ru,r in the silt deposit from these two in situ testing techniques. The cyclic threshold shear strain, γtp, to trigger ru,r observed from the T-Rex shaking equaled 0.007% to 0.011% and varied with the initial soil stiffness. The two testing techniques demonstrated that the in-situ shear modulus, G, reduced to 90% of the maximum shear modulus, Gmax, at γDSS,max≈γtp, whereas by γDSS,max≈1%, G further reduced to 10 to 30% of Gmax corresponding to ru,r of ∼60%. Changes in soil fabric were quantified using small-strain shear-wave velocity measurements performed before and/or upon initiation and after each stage of dynamic testing, and were linked to the observed increase and decrease in γtp for the shallower and deeper 3D elements, respectively, following T-Rex shaking. The side-by-side comparison of the dynamic responses and soil properties derived from these two distinctly different field-testing techniques validate the use of controlled blasting for quantifying in situ dynamic soil properties and responses.

Fracture mechanism and model of AA7075 multi-cavity component formed under complex stress states

During the multi-directional loading forming process of AA7075 aluminum alloy multi-cavity component, the stress states of material are complex and cracking defects are easy to occur, which seriously restricts the smooth process implementation and the improvement of forming quality. In this paper, based on the characteristic structure of AA7075 multi-cavity component, the material flow and stress states were studied. A trapezoidal groove shape specimen and test device were ingeniously designed. Then the fracture morphology, microstructure and mechanism of AA7075 alloy under different stress states are revealed. The results show that when the stress state changes from tensile-shear to pure shear and compression-shear, the fracture is easy to occur at the second phase particles, inclusions, the interface of elongated and equiaxed grains. The fracture modes are the mixture of surface shear fracture and core tensile fracture, but the proportion of shear plane is increasing. The grain morphology at the fracture surface is long grain with slightly increased axial diameter ratio, equiaxial grain with sufficient dynamic recrystallization, and slender shear band with large angle deflection, respectively. Further, a thermoforming fracture model under complex stress states in the process of multi-directional loading forming of multi-cavity components is established.

Design Rules of Bidirectional Smart Sensor Coating for Condition Monitoring of Bearings

This paper reports a novel monitoring technique of bearings' bidirectional load (axial and radial) based on a smart sensor coating, which is screen printed onto the surface of a cross-shaped steel substrate. To ensure the accuracy and stability of measurement as well as the durability of the printed coating, the developed prototype is built according to design rules commonly used in electronic circuits. The finite element model (FEM) is used to predict the mechanical property of the tested substrate under either unidirectional or bidirectional loads. Regarding the output voltage of the piezoelectric sensor, experimental results are revealed to be well-corelated to the numerical simulation. It is pointed out that the output signal generated from the sensor (electrode) could be particularly affected due to the capacitive parasite coming from the conductive tracks (CTs). Such a phenomenon might be reduced by printing them on the dielectric layer rather than on the piezocomposite layer. The study also investigates a highly anisotropic shape of electrodes (rectangular instead of circle), indicating that the orientation of such electrodes (axial or radial) does affect the output measurement. To sum up, the high performance of a sensor network coating depends not only on the ultimate characteristics of its own materials, but also on its structural design. Such an issue has been rarely reported on in the literature, but is nonetheless crucial to achieving reliable condition monitoring of bearings, especially for multidirectional loads-a key signature of early failure detection.

Effect of the Combination of Torsional and Tensile Stress on Corrosion Behaviors of Biodegradable WE43 Alloy in Simulated Body Fluid.

The real physiological environment of the human body is complicated, with different degrees and forms of loads applied to biomedical implants caused by the daily life of the patients, which will definitely influence the degradation behaviors of Mg-based biodegradable implants. In the present study, the degradation behaviors of modified WE43 alloys under the combination of torsional and tensile stress were systematically investigated. Slow strain rate tensile tests revealed that the simulated body fluid (SBF) solution could deteriorate the ultimate tensile stress of WE43 alloy from 210.1 MPa to 169.2 MPa. In the meantime, the fracture surface of the specimens tested in the SBF showed an intergranular corrosion morphology in the marginal region, while the central area appeared not to have been affected by the corrosive media. The bio-degradation performances under the combination of torsional and tensile stressed conditions were much more severe than those under unstressed conditions or single tensile stressed situations. The combination of 40 MPa tensile and 40 MPa torsional stress resulted in a degradation rate over 20 mm/y, which was much higher than those under 80 MPa single tensile stress (4.5 mm/y) or 80 MPa single torsional stress (13.1 mm/y). The dynamic formation and destruction mechanism of the protective corrosion products film on the modified WE43 alloy could attribute to the exacerbated degradation performance and the unique corrosion morphology. The dynamic environment and multi-directional loading could severely accelerate the degradation process of modified WE43 alloy. Therefore, the SCC susceptibility derived from a single directional test may be not suitable for practical purposes. Complex external stress was necessary to simulate the in vivo environment for the development of biodegradable Mg-based implants for clinical applications.

Nonlinear dynamics of an enhanced piezoelectric energy harvester composited of bi-directional functional graded materials

Given the energy harvesters in the engineering are often confronted with the possibility of catastrophic failure due to the multi-directional loads induced by the seismical or wind actions, a novel piezoelectric energy harvester made of bi-directional (2D) functional graded materials (FGMs) undergoing the large deformation is presented to resist the 2D loads so that the reliability of harvesting the vibration energy in the environment is enhanced. Taking the material properties continuously and smoothly varying across the axial and thickness directions of the substrate into account, Hamilton’s principle is used to establish the electromechanical model of distributed parameters based on the geometric nonlinearity. The Galerkin truncation and the harmonic balance method combined with the arc-length tracking continuation are applied to trace the frequency responses, which are compared with numerical solutions and the excellent agreements are obtained. The stability and bifurcation behaviors on the condition of resonance response interaction are predicted by Floquet’s theory. Numerical examples are disclosed that the effects of the excitation amplitude, damping coefficient, load resistance, axial and thickness FGMs indexes on the vibration displacement, output voltage, and power. Notably, the bifurcation behaviors of the proposed energy harvester may be tailored/tuned by multi-directional FGMs to achieve a wider frequency bandwidth and a higher harvesting power.

Mechanical properties of three-dimensional functionally graded triply periodic minimum surface structures

Lattice structures based on triply periodic minimum surfaces (TPMS) have received extensive attention due to their superior light-weighting and energy absorption properties. To generate a more competent design to accommodate multi-directional loading conditions in real-life applications, a three-dimensional functionally graded (FG-3D) TPMS structure was proposed in this study. Selective laser melting (SLM) was utilized to fabricate the designed TPMS lattice structures with Ti-6Al-4 V powder. They were investigated experimentally and numerically in terms of mechanical properties under different loading directions. The results indicated that the FG-3D Primitive (P) and Gyroid (G) structures can absorb 45.3% and 12% more energy than the uniform counterparts, respectively, and exhibit excellent energy absorption capacity under different loading directions. In contrast, the mechanical properties of both one- and two-dimensional FG structures might be inferior in some loading directions. Meanwhile, the parametric study of FG-3D structures was conducted and found that a large volume fraction and proper range of gradient variation are preferable for improving the energy absorption capability. These findings can provide guidelines on gradient design strategies, which can promote the application of energy-absorbing structures in real-life engineering.

Load distribution and radial deformations for planetary roller screw mechanism with axial load, radial load and turning torque

Obtaining the load distribution and radial deformations of planetary roller screw mechanism (PRSM) for the load carrying capacity design under complex loading conditions (multi-directional loads) is beneficial to decelerate fatigue and wear of threads. However, the combined effects of axial load, radial load and turning torque (overturning moment) were ignored in previous studies due to the complicated structure of PRSM. This paper presents a multi-roller beam-bar-spring (MR-BBS) model that incorporate radial load, turning torque and thread modification. The proposed model extended the theoretic method for calculating bending behavior of screw and rollers, which can more precisely describe the locus of the threads and roller axis. The load distribution of threads and load sharing among rollers of a PRSM under different external loads and cycling process are analyzed. The results show that the load distribution is more sensitive to turning torque of screw but relatively insensitive to the radial load. Moreover, the load distribution moderately changes with the variation of modification factor. Based on thread modification, the variable lead PRSM is proposed so that the uniformity of load sharing with complex load can be optimized. Highlights A multi-roller beam-bar-spring (MR-BBS) model is developed that incorporate axial load, radial load, turning torque and thread modification. The load distribution of threads and load sharing among rollers of a PRSM under different external loads and cycling process are analyzed. The load distribution is more sensitive to turning torque of screw but relatively insensitive to the radial load. The variable lead PRSM is proposed so that the uniformity of load sharing with complex load can be optimized.

Effect of stress rotation angles on dynamic responses of soft clay under multi-directional loading

Offshore wind turbines are subjected to significant combination environmental loads from wind and wave action. Under such conditions, the directions of these environmental loads vary over the structure's service life, and the stress directions of subsoil rotates during the wind turbine operating process. Tests were conducted on saturated soft clay using multi-directional cyclic simple apparatus to investigate the influence of stress rotation angle. All test results implied that both the stress rotation angles and cyclic stress ratios influence the dynamic responses of the reconstituted clay greatly and regularly: shear strain and pore pressure decrease as θ values vary from 0° to 90° and increase as θ changes between 120° and 180°. Shear strain accumulative ratio for θ = 0°, 30°, 150°, and 180° is more incredible than that of 60°, 120°, and 90°. Increasing the cyclic shear stress ratio will enhance the effect of θ on the cyclic strain and excess pore water pressure.

Multi-directional T-EMSD-based p-y model for recent loading history effects on lateral response of short pile and caisson in undrained clays

Rigid foundations supporting offshore wind turbines (OWT) like short piles and caissons can sustain multi-directional lateral loading. Moreover, the monotonic and cyclic response of these foundations can be affected by recent loading history aligned along directions different from the present one. To represent such recent loading history effects, a multi-directional p-y model is proposed for rigid foundations in undrained clays. The model is constructed by extending the uni-directional p-y model previously proposed by the authors based on Total-displacement-loading Extended Mobilisable Strength Design (T-EMSD) approach, and thus considering site-specific soil stress-strain relations and foundation geometries. The crux of the extension is to combine bounding surface plasticity and radial mapping with a moving projection center. The former effectively couples p-y response along orthogonal directions, while the latter is crucial for representing the influences of loading direction reversal and recent loading history effects. The proposed p-y model is evaluated against existing centrifuge tests and finite element analysis (FEA) of this work. Lastly, the proposed p-y model and FEA are used in parallel to highlight the effects of loading path rotation on monotonic and cyclic accumulative foundation response. These comparative analyses indicate that the proposed p-y model can reasonably represent recent loading history effects.

A Soft Robot With Variable Stiffness Multidirectional Grasping Based on a Folded Plate Mechanism and Particle Jamming

Despite good performance in grasping irregular fragile objects, soft grippers exhibiting low stiffness, and carrying capacity lack multidirectional grasping ability in the case of inclination. To address this problem, we propose a novel rigid and soft coupling variable stiffness module that employs a folded plate mechanism (FPM) to provide rigid multidirectional loading and combines it with particle jamming to achieve local variable stiffness with the characteristics of a finger grasping structure. Hence, a variable stiffness multidirectional soft grasping robot is developed to realize soft grasping and multidirectional rigid loading. The bending and stiffness control of the variable stiffness soft gripper is realized by a double-layer pneumatic driving structure with the advantages of simple control and corresponding speed. Moreover, good self-recovery is achieved with the soft outer layer since the particles can quickly return to the initial state due to partitioning of the FPM. Finally, prototype experiments verify its strong adaptability and stable multidirectional grasping ability, and experimental results show that the maximum grasping weight in each direction can be increased by more than three times with the variable stiffness.

Discrete-Element Simulation of Dense Sand under Uni- and Bidirectional Cyclic Simple Shear Considering Initial Static Shear Effect

Huge and critical structures, such as fuel storage tanks and nuclear power plants, are often built on dense sandy grounds, which may cause excessive plastic deformations under multidirectional cyclic shearing conditions caused by earthquakes. The lack of investigation of sand behavior under multidirectional loading may lead to unsafe designs, and thus significantly increase the maintenance cost for infrastructures during their long operational time, which might be longer than 100 years. This study presents a numerical investigation on the liquefaction behavior of dense sand under bidirectional cyclic simple shear using the discrete element method. The bidirectional cyclic simple shear tests with varying stress trajectories on the deviatoric stress plane, including figure-8, circular, and straight lines, were conducted. Additionally, a series of unidirectional loading tests was conducted in the simulation scheme for comparison purposes. The effect of the initial static shear on the cyclic behavior and liquefaction resistance of granular materials was examined. Four loading categories, including full reversal, partial reversal, intermediate reversal, and no reversal, were implemented in the numerical simulations. Although the presence of the initial static shear may enhance the cyclic resistance of granular samples under unidirectional loading, it mitigates the liquefaction resistance and promotes the failure of specimens under bidirectional shearing conditions. The microscopic analysis was performed to reveal the relationship between the fabric evolution and external loading, which can provide profound insights into the underlying mechanism of the cyclic behavior and liquefaction susceptibility of granular material when both the bidirectional shearing and initial static shear effects are considered.

Application of the generalized differential quadrature method to study vibration and dynamic stability of tri-directional functionally graded beam under magneto-electro-elastic fields

Given some engineering structures such as high-speed rail and aerospace structures are often affected by multidirectional thermal loads, we propose tri-directional functionally graded materials (3D FGMs) to fabricate a magneto-electro-elastic (MEE) Timoshenko beam placed on the Pasternak foundation to investigate the free vibration and dynamic stability. Unlike traditional bi-directional (2D) and unidirectional (1D) FGMs, we suppose the physical properties continuously and smoothly vary along the longitudinal, thickness, and width orientations, which satisfy the requirements of tri- directional function graded design. Considering the coupling between the MEE fields and 3D FGMs, as well as the Timoshenko beam theory, one leads to the equation of motion with variable coefficients of the structures by virtue of Hamilton's principle. Given the closed-form solution of free vibration of the antisymmetric composites such as tri-directional FGMs structures is difficult to find, a powerful methodology named the generalized differential quadrature method (GDQM) is applied to numerically solve the governing equation for predicting the dynamic behaviors. Numerical simulations are carried out to study the influences of 3D FMGs indexes, magneto-electro-mechanical loading, and foundation parameters on the natural frequency and stable boundary in detail. It is found that the interaction between hinged-hinged and 3D FMGs abnormally affects the fundamental frequency and dynamic stability, and the beams with higher magneto-electro-elastic parameters or larger foundation parameters or a lower length‐thickness ratio are more susceptible to destabilizing for all end supports. The results emanate that the 3D FGMs indexes can provide much wider space in tuning/tailing mechanical behaviors, which is different from the dynamic and stability of 1D and 2D FGMs structures.

Vertical response of unbonded fiber reinforced elastomeric isolators (U-FREIs) under bidirectional shear loading

Fiber Reinforced Elastomeric Isolators (FREIs) were generally studied in unbonded configuration. Due to combined axial and shear loads, the contact area between the bearing and horizontal supports reduces with the horizontal displacement. As a result, both the vertical and the horizontal stiffnesses decrease with the horizontal deformation while also the vertical deformation increases. This paper presents the results of a large set of full-scale 3D Finite Element Analyses on unbonded fiber reinforced bearings with different geometries, subjected to combined axial and multi-directional shear loads. The main vertical response parameters were studied, namely the vertical displacement, the vertical stiffness, and the effective compressive modulus, thus highlighting the influence of both geometry and horizontal loading direction on the vertical response of the FREIs. Conclusion of this study demonstrate to what extent the combined influence of geometric properties and loading conditions affects the vertical response of elastomeric bearings with flexible reinforcements.

Biaxial mechanical properties of the bronchial tree: Characterization of elasticity, extensibility, and energetics, including the effect of strain rate and preconditioning

Distal airways commonly obstruct in lung disease and despite their importance, their mechanical properties are vastly underexplored. The lack of bronchial experiments restricts current airway models to either assume rigid structures, or extrapolate the material properties of the trachea to represent the small airways. Furthermore, past works are exclusively limited to uniaxial testing; investigating the multidirectional tensile loads of both the proximal and distal pulmonary airways is long overdue. Here we present comprehensive mechanical and viscoelastic properties of the porcine airway tree, including the trachea, trachealis muscle, large bronchi, and small bronchi, via measures of elasticity, extensibility, and energetics to explore regional and directional dependencies, cross-examining strain rate and preconditioning effects using planar equibiaxial tensile tests for the first time. We find bronchial regions are notably heterogeneous, where the trachea exhibits greater stiffness, energy loss, and preconditioning sensitivity than the smaller airways. Interestingly, the trachealis muscle is similar to the distal bronchi, despite being anatomically located adjacent to the proximal ring. Tissues are anisotropic and axially stiffer under initial loading, losing more energy with greater stress relaxation circumferentially. Strain rate dependency is also noted, where tissues are more energetically efficient at the faster strain rate, likely attributable to the microstructure. Findings highlight assumptions of homogeneity and isotropy are inadequate, and enable the improvement of aerosol flow and dynamic airway deformation computational predictive models. These results provide much needed fundamental material properties for future explorations contrasting healthy versus diseased pulmonary airway mechanics to better understand the relationship between structure and lung function. Statement of significanceWe present comprehensive multiaxial mechanical tensile experiments of the proximal and distal airways via measures of maximum stress, initial and ultimate moduli, strain and stress transitions, hysteresis, energy loss, and stress relaxation, and further assess preconditioning and strain rate dependencies to examine the relationship between lung function and structure. The mechanical response of the bronchial tree demonstrates significant anisotropy and heterogeneity, even within the tracheal ring, and emphasizes that contrary to past studies, the behavior of the proximal airways cannot be extended to distal bronchial tree analyses. Establishing these material properties is critical to advancing our understanding of airway function and in developing accurate computational simulations to help diagnose and monitor pulmonary diseases.

Accumulated displacement and unloading stiffness variations of modified suction caisson in sand under multidirectional lateral cyclic loading

The modified suction caisson (MSC) is an innovative foundation for offshore wind turbines. Model tests were conducted to study the bearing behavior of the regular suction caisson (RSC) and the MSC in sand under multidirectional lateral cyclic loads. Each test includes two stages: (a) the load was applied in the initial loading direction, and (b) the load was applied in the direction which rotate through a deflection angle from the initial loading direction. Results show that in the first stage, the translational motion direction of suction caisson in plane view coincides with the loading direction. In the second stage, the motion direction of the suction caisson doesn't coincide with the loading direction. This phenomenon becomes more obvious under low loading amplitude. When the deflection angle is less than 90°, total accumulated displacement increases with increasing the load cycles. The maximum normalized total displacements for the RSC (ζb = 0.833) and the MSC (ζb = 0.649, 0.833) were obtained when the deflection angles equal 45°, 45° and 30°. When the deflection angle value is higher than 90°, the total displacement decreases with increasing the deflection angle. Changing the loading direction has little effect on the unloading stiffness values for both the RSC and the MSC.

Numerical Study on Seismic Response of Offshore Wind Turbine Monopile in Multi-Layered Soil Profile of Arabian Sea

The seismic performance of monopiled offshore wind turbine (OWT) structures was evaluated numerically. The aim was to analyze offshore wind farm sites on complicated layered seabed with high seismicity. Following pile soil analysis (PISA) model, three-dimensional (3D) numerical evaluations were undertaken for two separate locations under two independent seismic events. The effects of pile diameter, depth, site impact owing to transverse soil layering, uni-directional and multi-directional seismic loading and seismic acceleration magnitude are presented. Dynamic impedance depth variation and site response analysis via lateral displacement, lateral soil response and Fourier response amplitude are explored in frequency and time domain. In a seismic zone with stratified soil, pile diameter has a greater influence. Variations in soil profile affect wind turbine performance and seismic sensitivity. This research will give a strong platform for later studies to recommend a safe wind farm site based on simulation results.

Taking a stab at modelling canine tooth biomechanics in mammalian carnivores with beam theory and finite-element analysis.

Canine teeth are vital to carnivore feeding ecology, facilitating behaviours related to prey capture and consumption. Forms vary with specific feeding ecologies; however, the biomechanics that drive these relationships have not been comprehensively investigated. Using a combination of beam theory analysis (BTA) and finite-element analysis (FEA) we assessed how aspects of canine shape impact tooth stress, relating this to feeding ecology. The degree of tooth lateral compression influenced tolerance of multidirectional loads, whereby canines with more circular cross-sections experienced similar maximum stresses under pulling and shaking loads, while more ellipsoid canines experienced higher stresses under shaking loads. Robusticity impacted a tooth's ability to tolerate stress and appears to be related to prey materials. Robust canines experience lower stresses and are found in carnivores regularly encountering hard foods. Slender canines experience higher stresses and are associated with carnivores biting into muscle and flesh. Curvature did not correlate with tooth stress; however, it did impact bending during biting. Our simulations help identify scenarios where canine forms are likely to break and pinpoint areas where this breakage may occur. These patterns demonstrate how canine shape relates to tolerating the stresses experienced when killing and feeding, revealing some of the form–function relationships that underpin mammalian carnivore ecologies.

A 3D metamaterial with negative stiffness for six-directional energy absorption and cushioning

To attenuate the impact acceleration under multidirectional loads, a mechanical metamaterial with six-directional cushioning and energy-absorbing properties is urgently needed. The study proposes a 3D negative stiffness (NS) metamaterial (NS-MM), which exhibits a bidirectional NS effect and cushion capacity under compressive and tensile loading in three principal directions. The unit cell of NS-MMs contains three pairs of parallel cross-curved beams mounted in a cubical frame, and the NS effect is obtained by controlled elastic buckling of the cross-curved beams. The mechanical analysis of one unit cell is conducted toward predicting the static response. The static performance of the NS-MMs composed of 1×1×1 and 2×2×2 unit cells in three principal directions is investigated by numerical calculations and experiments with quasi-static tension–compression conditions. Comprehensive results indicate the proposed structure has the characteristics of shape recovery, bidirectional NS property, and good energy absorption under tension and compressive loads in one principal direction and has the same mechanical properties in three principal directions. Transient dynamic analysis is exploited to investigate the cushioning performance. The obtained response acceleration (RA) is effectively attenuated in both directions and limited to a certain threshold.

Ultrasound-Guided Anterior Talofibular Ligament Repair With Augmentation Can Restore Ankle Kinematics: A Cadaveric Biomechanical Study.

Background:Anterior talofibular ligament (ATFL) repair of the ankle is a common surgical procedure. Ultrasound (US)-guided anchor placement for ATFL repair can be performed anatomically and accurately. However, to our knowledge, no study has investigated ankle kinematics after US-guided ATFL repair.Hypothesis:US-guided ATFL repair with and without inferior extensor retinaculum (IER) augmentation will restore ankle kinematics.Study Design:Controlled laboratory study; Level of evidence, 4.Methods:A 6 degrees of freedom robotic testing system was used to apply multidirectional loads to fresh-frozen cadaveric ankles (N = 9). The following ankle states were evaluated: ATFL intact, ATFL deficient, combined ATFL repair and IER augmentation, and isolated US-guided ATFL repair. Three loading conditions (internal-external rotation torque, anterior-posterior load, and inversion-eversion torque) were applied at 4 ankle positions: 30° of plantarflexion, 15° of plantarflexion, 0° of plantarflexion, and 15° of dorsiflexion. The resulting kinematics were recorded and compared using a 1-way repeated-measures analysis of variance with the Benjamini-Hochberg test.Results:Anterior translation in response to an internal rotation torque significantly increased in the ATFL-deficient state compared with the ATFL-intact state at 30° and 15° of plantarflexion (P = .022 and .03, respectively). After the combined US-guided ATFL repair and augmentation, anterior translation was reduced significantly compared with the ATFL-deficient state at 30° and 15° of plantarflexion (P = .0012 and .005, respectively). Anterior translation was not significantly different for the isolated ATFL-repair state compared with the ATFL-deficient or ATFL-intact states at 30° and 15° of plantarflexion.Conclusion:Combined US-guided ATFL repair with augmentation of the IER reduced lateral ankle laxity due to ATFL deficiency. Isolated US-guided ATFL repair did not reduce laxity due to ATFL deficiency, nor did it increase instability compared with the intact ankle.Clinical Relevance:US-guided ATFL repair with IER augmentation is a minimally-invasive technique to reduce lateral ankle laxity due to ATFL deficiency. Isolated US-guided ATFL repair may be a viable option if accompanied by a period of immobilization.