Additional Axial Load Research Articles

Nonlocal dynamic response of FGP sandwich microbeam with 2D PSH network incorporating adatoms-surface interactions energy under magnetic field

The present work models and studies the resonance frequency change due to adsorption phenomena in a simply-supported adatom-microbeam system under an axial magnetic environment. The microbeam structure is a functionally graded (FG) sandwich that includes a rectangular configuration and a ceramic perforated core with periodic square holes network and FG porous material faces. To evaluate the adsorption-induced energies produced by van der Waals interaction (vdW), the Morse and Lennard-Jones (6–12) potentials are included in conjunction with nonlocal material elasticity to adopt the small-scale impact. Moreover, the explicit formulas for the inertia moments and shear force are developed by the Timoshenko beam equations, considering the residual stress influence as an additional axial load. The Navier-type solution and the differential quadratic method (DQM) are implemented to compute the solution of the governing equations. It is established that the resonance frequency change for the O/Si (100) and H/Si (100) is dependent on the geometrical, perforation, and porosity parameters, adsorption density, mode number, and the magnetic field intensity as well. Therefore, these numerical results have been discussed in detail to properly examine dynamic vibration behavior and a suitable mass detection design of M/NEMS structures.

Effect of forced assembly on bearing performance of single-lap, countersunk composite bolted joints – Part Ⅱ: Numerical investigation

A progressive damage model with the combination of 3D Hashin criterion and exponential material degradation was developed and validated according to the experimental results of the Part Ⅰ. The effect of forced assembly on stress distribution and bearing damage of single-lap, countersunk composite bolted joints were revealed by utilizing the present model. It is found that the joints with forced assembly show higher contact stress levels. The stress distribution of the countersunk hole tends to be uniform, while that of the non-countersunk hole is more uneven, and the maximum contact stress occurs at the non-countersunk hole. Furthermore, the forced assembly made a bolt sustain additional axial tensile load, introducing high failure risks to the bolts. With forced assembly, the fiber compressive damage and in-plane matrix compressive damage are more serious, and the most serious damage is transferred from the countersunk hole to the non-countersunk hole.

Influence of Axial Load and a 45-Degree Flexion Head Position on Cervical Spinal Stiffness in Healthy Young Adults

Background: Neck pain is a major cause of disability worldwide. Poor neck posture such as using a smartphone or work-related additional cervical axial load, such headgear of aviators, can cause neck pain. This study aimed at investigating the role of head posture or additional axial load on spinal stiffness, a proxy measure to assess cervical motor control.Methods: The posterior-to-anterior cervical spinal stiffness of 49 young healthy male military employees [mean (SD) age 20 ± 1 years] was measured in two head positions: neutral and 45-degree flexed head position and two loading conditions: with and without additional 3 kg axial load. Each test condition comprised three trials. Measurements were taken at three cervical locations, i.e., spinous processes C2 and C7 and mid-cervical (MC).Results: Cervical spinal stiffness measurements showed good reliability in all test conditions. There was a significant three-way interaction between location × head position × load [F(2, 576) = 9.305, p < 0.001]. Significant two-way interactions were found between measurement locations × loading [F(2, 576) = 15.688, p < 0.001] and measurement locations × head position [F(2, 576) = 9.263, p < 0.001]. There was no significant interaction between loading × head position [F(1, 576) = 0.692, p = 0.406]. Post hoc analysis showed reduction of stiffness in all three measurement locations in flexion position. There was a decrease in stiffness in C2 with loading, increase in stiffness in C7 and no change in MC.Discussion: A flexed head posture leading to decreased stiffness of the cervical spine might contribute to neck pain, especially if the posture is prolonged and static, such as is the case with smartphone users. Regarding the additional load, stiffness decreased high cervical and increased low cervical. There was no change mid cervical. The lower spinal stiffness at the high cervical spine might be caused by capsular ligament laxity due to the buckling effect. At the lower cervical spine, the buckling effect seems to be less dominant, because the proximity to the ribs and sternum provide additional stiffness.

Improved design criterion for frictionally engaged contacts in overrunning clutches

Overrunning clutches, also known as freewheel clutches, are frictionally engaged, directional clutches; they transmit torque depending on the Freewheel clutch rings’ rotation directions. The torque causes a tangential force in the Hertzian contact area. The hitherto “state-of-the-art design criterion” bases on this load situation. In practice, axial loads additionally act on the frictionally engaged Hertzian contact area. This additional axial load can cause the loss of the friction connection and so the freewheel clutch slips. This publication presents an improved design criterion for frictionally engaged contacts in freewheel clutches. It allows to consider tangential as well as axial loads during the design process. Additionally, it offers the possibility to estimate the probability of frictional engagement loss and gross slip based on the freewheel clutch’s application scenario. This publication points out how to use the improved design criterion to design freewheel clutches that are more robust against a loss of function.

Fatigue Life of Sn3.0Ag0.5Cu Solder Alloy Under Combined Cyclic Shear and Constant Tensile/Compressive Loads

Abstract Solder joints in electronic assemblies experience damage due to cyclic thermomechanical loading that eventually leads to fatigue fracture and electrical failure. While solder joints in smaller, die-sized area-array packages largely experience shear fatigue due to thermal expansion mismatch between the component and the substrate, larger area-array packages experience a combination of cyclic shear and axial tensile/compressive loads due to flexure of the substrate. Additionally, on larger processor packages, the attachment of heatsinks further exacerbates the imposed axial loads, as does package warpage. With the increase in size of packages due to 2.5D heterogeneous integration, the above additional axial loads can be significant. Thus, there exists a critical need to understand the impact on fatigue life of solder joints with superposed compressive/tensile loads on the cyclic shear loads. In this paper, we describe a carefully constructed multi-axial microprecision mechanical tester as well as fatigue test results on Sn3.0Ag0.5Cu (SAC305) solder joints subjected to controlled cyclic shear and constant compressive/tensile loads. The tester design allows one to apply cyclic shear loads up to 200 N while maintaining a constant axial load of up to 38 N in tension or compression. The tester is capable of maintaining the axial load to within a tolerance of ±0.5 N during the entirety of fatigue experiment. Carefully constructed test specimens of Sn3.0Ag0.5Cu solder joints were isothermally fatigued under systematically increased compressive and tensile loads imposed on the test specimen subject to repeated loading (R = 0) under lap-shear. In general, the imposition of the superposed compressive load increases the fatigue life of the solder joint compared to application of pure cyclic shear, while the imposition of the superposed tensile load decreases the fatigue life. At larger compressive loads, friction between fractured surfaces is responsible for significant energy dissipation during the cyclic load–unload cycles.

Anomalous inflation of a nematic balloon

Inflation of an elastomer balloon is one of the most classical and important problems in the field of nonlinear elasticity. Many intriguing phenomena associated with the inflation of elastomer balloons such as snap-through instability and bulge propagation have been often observed and intensively studied. In this article, we report a new phenomenon during the inflation of a cylindrical balloon made from nematic elastomer. We found in the experiment that with a small increment of inflating pressure, the balloon contracts significantly along its axial direction while expands in its radial direction. With further increase of the pressure, the balloon expands mainly in the radial direction while maintains its length almost unchanged. Finally, the balloon expands both in the radial and axial directions abruptly with a tiny increase of inflating pressure, often leading to rupture of the balloon. The inflation behavior of the nematic balloon can be changed when it is subjected to an additional axial load. To quantitatively understand the experiments, we adopt a quasi-convex free energy function of nematic elastomer to derive the relationship between the inflating pressure and its deformation state. We have shown that the anomalous inflation of the nematic balloon is closely associated with the soft elasticity of the nematic elastomer. Our theoretical predictions agree with experimental measurements well with only two material parameters separately determined by uniaxial tension test of nematic elastomer.

The effect of weld residual stress on fracture toughness at the intersection of two welding lines of offshore tubular structure

Due to the spatial complexity and fabrication characteristics of offshore platforms, it is inevitable to encounter overlaps or proximity of weld lines in tubular joints. Several international standards such as American Petroleum Institute (API), American Welding Society (AWS), and American Institute of Steel Construction (AISC) regulate the minimum distance between primary weld beads; however, any logical and detailed background of this limitation has not been presented. For a non-compliant weld joint where the regulation is not met, fracture toughness calculation is a typical index to verify the structural integrity.This research consists of two parts. First, weld residual stress distributions are calculated by a 3D thermo-mechanical nonlinear Finite Element Analysis. Two crossing welds, a T-weld crossing on a butt weld, are simulated in one model. A separate tee and a butt welding simulations are also performed for a comparative purpose. Second, SIFs and J-integral values are calculated at the surface and deepest crack tip locations for four different types of semi-elliptical surface cracks. Four cracks are embedded into the weld model and the residual stress distribution from the 3D thermo-mechanical FEA are mapped to a 3D FE crack model as initial conditions. An additional axial tensile load is also imposed. SIF values are compared with those using the weighting function method for the butt weld model subject to three load cases, i.e., tensile stress only, weld residual stress only, and both of them. From the simulation, a tubular joint containing a chord girth weld intersected with weld beads of brace is found to show lower the SIF values than that having only a girth weld on chord.

Influence of body position and axial load on spinal stiffness in healthy young adults.

This study aimed at investigating the effects of different body positions and axial loads on spinal stiffness to better understand spinal stabilisation mechanisms. The posterior-to-anterior lumbar and thoracic spinal stiffness of 100 young healthy adults (mean age 23years; 50 females) were measured in three test situations: prone, standing and standing while carrying a load equal to 50% of the subject's body weight. Each test situation comprised three trials. Spinal stiffness in all test situations showed good reliability. Repeated measures analysis of covariance showed significantly higher spinal stiffness in standing than in the prone position [F(1/1694) = 433.630, p < 0.001]. However, spinal stiffness was significantly lower when standing while carrying a load of 50% of the body weight than when standing without additional load [F(1/1494) = 754.358, p < 0.001]. This study showed that spinal lumbar and thoracic stiffness increases when body position is changed from prone to standing. Additional axial load of 50% of the subject's body weight results in reduced spinal stiffness during standing. These slides can be retrieved under Electronic Supplementary Material.

Slope-reducing tibial osteotomy decreases ACL-graft forces and anterior tibial translation under axial load.

Posterior tibial slope (PTS) represents an important risk factor for anterior cruciate ligament (ACL) graft failure, as seen in clinical studies. An anterior closing wedge osteotomy for slope reduction was performed to investigate the effect on ACL-graft forces and femoro-tibial kinematics in an ACL-deficient and ACL-reconstructed knee in a biomechanical setup. Ten cadaveric knees with a relatively high native slope (mean ± SD): (slope 10°±1.4°, age 48.2years ± 5.8) were selected based on prior CT measurements. A 10° anterior closing-wedge osteotomy was fixed with an external fixator in the ACL-deficient and ACL-reconstructed knee (quadruple Semi-T/Gracilis-allograft). Each condition was randomly tested with both the native tibial slope and the post-osteotomy reduced slope. Axial loads (200N, 400N), anterior tibial draw (134N), and combined loads were applied to the tibia while mounted on a free moving and rotating X-Y table. Throughout testing, 3D motion tracking captured anterior tibial translation (ATT) and internal tibial rotation (ITR). Change of forces on the reconstructed ACL-graft (via an attached load-cell) were recorded, as well. ATT was significantly decreased after slope reduction in the ACL-deficient knee by 4.3mm ± 3.6 (p < 0.001) at 200N and 6.2mm ± 4.3 (p < 0.001) at 400N of axial load. An increase of ITR of 2.3° ±2.8 (p < 0.001) at 200N and by 4.0° ±4.1 (p < 0.001) at 400N was observed after the osteotomy. In the ACL-reconstructed knee, ACL-graft forces decreased after slope reduction osteotomy by a mean of 14.7N ± 9.8 (p < 0.001) at 200N and 33.8N ± 16.3 (p < 0.001) at 400N axial load, which equaled a relative decrease by a mean of 17.0% (SD ± 9.8%), and 33.1% (SD ± 18.1%), respectively. ATT and ITR were not significantly changed in the ACL-reconstructed knee. Testing of a tibial anterior drawing force in the ACL-deficient knee led to a significantly increased ATT by 2.7mm ± 3.6 (p < 0.001) after the osteotomy. The ACL-reconstructed knee did not show a significant change (n.s.) in ATT after the osteotomy. However, ACL-graft forces detected a significant increase by 13.0N ± 8.3 (p < 0.001) after the osteotomy with a tibial anterior drawer force, whereas the additional axial loading reduced this difference due to the osteotomy (5.3N ± 12.6 (n.s.)). Slope-reducing osteotomy decreased anterior tibial translation in the ACL-deficient and ACL-reconstructed knee under axial load, while internal rotation of the tibia increased in the ACL-deficient status after osteotomy. Especially in ACL revision surgery, the osteotomy protects the reconstructed ACL with significantly lower forces on the graft under axial load.

Optimization of height-wise damper distributions considering practical design issues

This paper discusses the optimal height-wise distribution of supplemental viscous dampers in multistorey building structures. Seismic excitation is modeled as stochastic stationary process and response statistics for linear structural systems are obtained through state-space analysis. For nonlinear damper applications statistical linearization is employed to accommodate a similar, state-space formulation. Emphasis is placed on three practical design issues: (i) realistic quantification of damper upfront cost based on damper force capacity rather than on the damping coefficient; (ii) investigation of bracing configuration schemes anchored at non-consecutive floor levels; and (iii) consideration of the cost of column strengthening required to accommodate the additional axial loads due to the supplemental damping system. Five different cost-based objective functions are defined to address these issues and the impact of each of them on the optimal damper distribution is examined in detail. Adjustments for estimation of peak responses when statistical linearization is used are also discussed. The optimal design problem considers the structural performance as a constraint, requiring that a target vibration suppression be achieved through the damper addition. An extension to a multi-objective design optimization is also discussed, incorporating the vibration suppression level as additional objective. The proposed approach is illustrated considering an actual Chilean 26-storey building subjected to an excitation compatible with the Chilean seismic hazard. Results show that damper distributions optimized considering realistic cost assessments are more efficient (with respect to cost-based design objectives) than distributions optimized considering simplified criteria. It is also demonstrated that consideration of practical issues such as column strengthening and feasible damper force capacity have a considerable influence on the optimal distribution. Finally, results also show that further cost reductions can be achieved with braces anchored at non-consecutive floor levels, and that such reductions are consistent with predictions given by approximate analytical expressions.

Dynamic Analysis of Helical Planetary Gear Sets under Combined Force and Moment Loading

The dynamic behavior of a single-stage planetary gear set with helical gears of multishaft automotive automatic transmissions has been studied, in which one component of the planetary gear set is imposed by additional external vertical and axial loading from countershaft gear pair in addition to the moment. Under these combined loading conditions, the contributions of the deflections of the ring gear and the carrier cannot be neglected. A three-dimensional nonlinear time-variant dynamic model considering not only the transverse, torsional, axial, and rotational motions of the gears but also the elasticity of the mounted shafts has been developed by combining the lumped parameter method with finite element method. The natural modes and the forced vibration responses due to static transmission errors have been obtained. The proposed dynamic model is employed to describe the effects of the combined external loading condition and positioning on the dynamic behavior of a four-planet system.

Understanding of elastic anisotropy of shale under triaxial loading: Porosity-deformation approach

Theoretical models for the description of stress dependencies for anisotropic rocks are important for building velocity models and the interpretation of seismic data with respect to stress, lithology, and pore content. Especially important is the accurate description of the change of anisotropy due to applied anisotropic stress by means of a quantitative model to aid the interpretation. The porosity-deformation approach (PDA; originally introduced as the piezosensitivity theory) describes stress-induced changes of elastic properties without any knowledge about the geometry and orientation of the microcracks. We have developed a formulation of the theory for a transverse isotropic rock, which was loaded parallel to the bedding plane, and we found that it can be described theoretically as an orthorhombic rock. We also found out how properties that described the velocity change due to hydrostatic loading can be used to predict elastic anisotropy under additional axial loading. The number of free parameters are reduced by using the PDA compared with phenomenological fitting of data. We have used literature data of ultrasonic-wave velocity obtained during the geomechanical multistage measurements on a water-saturated Norwegian Sea shale sample to test the adapted theory. In a first step, we found that the PDA well-described the hydrostatic velocity-stress dependency. The obtained stress sensitivity and compliant porosity values give reasonable results compared with the microstructure of shales. In a second step, the obtained parameters were used for predicting the obtained shear compliances under triaxial stress conditions. Our results help to give an interpretation of the components of the stress sensitivity that describes the S-wave velocities.

The ratchet–shakedown diagram for a thin pressurised pipe subject to additional axial load and cyclic secondary global bending

The ratchet and shakedown boundaries are derived analytically for a thin cylinder composed of elastic-perfectly plastic Tresca material subject to constant internal pressure with capped ends, plus an additional constant axial load, F, and a cycling secondary global bending load. The analytic solution is in good agreement with solutions found using the linear matching method. When F is tensile, ratcheting can occur for sufficiently large cyclic bending loads in which the pipe gets longer and thinner but its diameter remains the same. When F is compressive, ratcheting can occur in which the pipe diameter increases and the pipe gets shorter, but its wall thickness remains the same. When subject to internal pressure and cyclic bending alone (F = 0), no ratcheting is possible, even for arbitrarily large bending loads, despite the presence of the axial pressure load. The reason is that the case with a primary axial membrane stress exactly equal to half the primary hoop membrane stress is equipoised between tensile and compressive axial ratcheting, and hence does not ratchet at all. This remarkable result appears to have escaped previous attention.

3차원 수치해석을 이용한 기계진동을 받는 단말뚝의 허용 연직지지력 산정방법 검토

본 연구에서는 국내에서 통상적으로 적용하고 있는 플랜트 진동기기초의 연직지지력 산정 방법의 타당성을 검토하고자 하였다. 이를 위하여 현재 작동중인 진동기계를 지지하고 있는 군말뚝 기초 중 단일 말뚝을 대상으로, 경험적 지지력 산정식을 이용하여 말뚝-지반의 상호작용을 고려할 수 있는 3차원 단말뚝 하중-변위 거동 수치모형을 구성하였다. 구성된 수치모형에 대하여 허용하중까지 축방향 정하중을 재하한 후, 추가로 단말뚝 두부에 기계 진동을 가하는 3차원 동적해석을 수행하여, 기계진동에 의해 추가적으로 말뚝 두부에 발생할 수 있는 연직하중을 산정하였다. 해석결과, 기계진동에 의해 발생하는 추가적인 동적하중은 정적 허용하중의 약 13% 정도로 나타나, 모든 진동 및 지반조건에 대하여 동적하중이 정적 사용하중의 100%로 증가된다고 간주하고 설계하는 국내 설계 관행은 지극히 보수적이며 과다설계로 이어질 수 있음을 보여주었다. In this study, the applicability of the method for evaluating the axial bearing capacity of a single pile subjected to machine vibration, which is generally applied in Korea, is examined. Firstly, the 3D model for the load-displacement behavior of a single pile, which is one of the group pile supporting a rotating machine, was constituted. In the constituted numerical model, the soil-pile interaction was considered by using the empirical formulae for evaluating axial bearing capacity and conducting the repeated numerical analyses. After the model was statically loaded to the allowable bearing load in static numerical analysis, the axial vibration due to machine vibration was added to the pile top in dynamic numerical analysis. From these procedures, the additional axial dynamic load caused by machine vibration was computed. From the analysis results, it was found that the additional dynamic load caused by machine vibration was about 13% of the allowable static load and it was thought that the domestic design concept, assuming that the additional dynamic load due to machine vibration equals to the allowable static load, is excessively conservative.

The effects of scoop sampling on the creep behaviour of power plant straight pipes

Small specimen testing techniques are potentially highly useful procedures which could be used to determine many fundamental material properties from relatively small amounts of sample material. Small specimens can be manufactured from scoop samples taken from the surface of a component, allowing for continued operation after sampling. In the past, it has been assumed that, provided the wall thickness dimension around the specimen sample site is greater than the minimum design requirement, the action of scoop sampling will not greatly compromise the future operation of the component. Little study has been completed, however, to verify this assumption or to evaluate the likely reduction in remnant life due to scoop sampling. In the present study, a finite element investigation is made into the effects of scoop sampling on the stress states and failure lives of power plant straight pipes under steady-state creep conditions. Loading conditions considered include an internal pressure load only (assuming closed-end conditions), as well as system loading (in the form of additional axial and in-plane bending moment loading). Typically, the application of system loading increases the likelihood of failure being controlled by the stress states in the vicinity of a scoop excavation. This leads to potentially significant reductions (up to approximately 90%) in creep life of straight piping components. Parametric equations (valid for a range of pipe geometries and scoop cut depths) have been proposed, which can estimate the stress riser effect in the vicinity of an excavation sample under closed-end and additional axial loading conditions.

Non-standard stabilization of the post-buckling path for elastic cylindrical shells under combined state of loadings

The post-buckling path for cylindrical shells under external pressure and twisting moment is unstable. The effect of stabilization in most cases is obtained by changing geometry of the structure. In this paper an alternative concept is applied, namely stabilization of the unstable post-buckling path is achieved by application of additional axial loads imposed to the ends of the structure without changing its shape and sizes. Three types of stabilizing forces were investigated: active forces applied to the structure or passive ones or combinations of both. Calculations were performed using ANSYS 11.0 code for elastic shells under different combinations of loadings.

Coupled-Consolidation Modeling of a Pile in Consolidating Ground

When a pile is embedded in a consolidating ground (e.g., newly reclaimed land), soil may settle more than the pile, thus generating negative skin friction along the pile shaft. This negative friction induces additional axial load to the pile (dragload) and pulls the pile further downward (downdrag). In this paper, the problem is investigated numerically with the finite-element package ABAQUS. It was found that the package defaults an interface model that models the mobilized interface strength in a way that the effect of water pressure was overlooked. Therefore, a modified numerical algorithm is proposed in this study. It amends the model by correctly bringing pore water pressure into the calculation steps. which properly simulates the effective stress-dependent nature of the shear strength at the soil-pile interface. The algorithm is then verified by a self-contained simple to understand simulation. A case history of two piles (one of them coated with bitumen) embedded in a consolidating soft ground is then back analyzed with the proposed algorithm. Fully coupled consolidation and geometric nonlinearity are also considered in the analyses. The transient response of the problem is investigated, including the development of dragload, downdrag, and neutral plane with time. The simulation generally fits well with the field measurements. Parametric studies of the effects of pile head loading reveal that the position of the neutral plane depends not only on the magnitude of the applied pile head loading, but is also affected when the load is applied with respect to the consolidation process. DOI: 10.1061/(ASCE)GT.1943-5606.0000651. © 2012 American Society of Civil Engineers.

Transverse Vibration Analysis of Single-Walled Carbon Nanotubes Embedded in an Elastic Medium Using Bernoulli-Fourier Method

Based on the Timoshenko beam theory and Bernoulli-Fourier method, a single-elastic beam model is developed for transverse vibrations of single-walled carbon nanotubes under additional axial load, which includes the effects of the elastic medium around them. Explicit expressions are derived for the natural frequencies and transversal responses of simply supported single-walled carbon nanotubes. The influence of addition axial load and the properties of elastic medium on the vibrations are discussed. The results showed that the effects of addition axial load on the lower natural frequencies of single-walled carbon nanotubes are sensitive to the lower vibration modes and the stiff elastic medium. The lower natural frequencies depend on the axial load; they become smaller with increasing axial load and vary with the vibration modes. In addition, except for the first mode, the effects of the axial load on the stiff elastic medium are considerably greater than those on the flexible one. However, the constants of the elastic medium have little effect on the first mode. The critical axial buckling stress and strain for simply-supported single-walled carbon nanotubes are also obtained.

Precision Influence of Sickle-Like Curve of Hot Rolled Strip on Rotary Shear's Cutting

Push-pull pickling line of a branch of WISCO frequently comes up the faults that rotary shear axial locking is unreliable and the cutting precision is low. To solve this problem, two kinds of sickle-like curve have been analyzed, the graphic method and the finite element method were used. The research come to the conclusion that frequent appearance sickle-like curve would produce additional axial impact load on rotary shear's shear blade and also calculated value of axial static load. These are the main reason why the faults appear. After took the proposed solutions accordingly to improve the locking force, the down time were greatly reduced and the cutting precision were improved significantly.

Axial Loading Cross Screw Fixation for the Austin Bunionectomy

The Austin procedure has become a common method of osteotomy for the correction of hallux abductovalgus when indicated. The V-type configuration is intrinsically stable but not without complications. One complication encountered is rotation and/or displacement of the capital fragment. We present the use of an axial loading screw in conjunction with a dorsally placed compression screw. The benefit to this technique lies in the orientation of the axial loading screw, because it is directed to resist the ground reactive forces while also providing a second point of fixation in a crossing screw design. In a head-to-head biomechanical comparison, we tested single dorsal screw fixation versus double screw fixation, including both the dorsal and the axial loading screws in 10 metatarsal Sawbones ® (Pacific Research Laboratories Inc, Vashon, WA). Five metatarsals received single dorsal screw fixation and five received the dorsal screw and the additional axial loading screw. The metatarsals were analyzed on an Instron compression device for comparison; 100% of the single screw fixation osteotomies failed with compression at an average peak load of 205 N. Four of five axial loading double screw fixation osteotomies did not fail. This finding suggests that the addition of an axial loading screw providing cross screw orientation significantly increases the stability of the Austin osteotomy, ultimately decreasing the likelihood of displacement encountered in the surgical repair of hallux abductovalgus.