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This paper presented the experimental results of the strength capacity of studs embedded centrally in concrete with red mud synthetic coarse aggregates, with the variation of the handcrafted headed stud thickness (3.17, 4.76, 6.35, and 7.9 mm) and no shank bond influence with concrete. The results regarding the compressive strength of concrete showed considerable strength gain with synthetic coarse aggregate, ranging from 27.00 to 43.50 MPa, while in concrete with natural coarse aggregate, the variation was 27.00 to 36.50 MPa. Also, it was observed that the cracking in the concrete matrix of the synthetic coarse aggregate occurred in the aggregate instead of the transition zone, as occurred with the natural coarse aggregate concrete. However, the solid morphological formation of synthetic coarse aggregate provided excellent chemical adhesion to the headed stud, providing a hardening failure behavior after reaching the yield strength value of the steel bar with higher displacements. This can enable the optimized consumption of materials in the dosage of low‐strength structural concrete and the anchoring application of studs with smaller‐headed thicknesses, up to 8% of head diameter, generating economy and sustainability. [ABSTRACT FROM AUTHOR]

A novel technique for evaluating roller expansion joint quality of ASTM A192 carbon steel tubes to SA 299 Gr.A tube sheet by correlation with its magnetic coercive force (MCF) has been presented. Roller expansion joint strength in respect of different percentages of apparent wall reduction (%WR) and temperature rise up to 600 °C was studied. The MCF, hardness values, pull-out strength, and microstructure of roller expanded joints were compared and analyzed concerning various %WR. It is observed that MCF and hardness values increase uniformly up to 12%WR with an increase in pull-out strength. A correlation between hardness and MCF was found. However, the development of severe plastic deformation at the inner tube surface above 12%WR gives a sharp rise in MCF values with decreased pull-out strength, which indicates over-expansion. Recovery and recrystallization of expansion joints during repair of neighboring tube reduce hardness, MCF, and pull-out strength with little change in microstructure. The MCF value after rolling has been critical to obtaining maximum strength. The study evaluated criteria for expansion joint quality using MCF within the recommended expansion range of 6-12%WR. It is inferred that MCF can effectively monitor expansion joint strength during initial rolling and after repair. [ABSTRACT FROM AUTHOR]

This study evaluated the uniaxial tensile strength and bond performance of natural hybrid reinforcement bars. Hybrid FRP combines multiple fibers and matrixes, resulting in a desirable performance. Two types of hybrid bars were tested: one with natural fibers surrounded by glass fiber, and the other with a steel core surrounded by natural fiber and then glass fiber. Thirteen samples were used to assess tensile behavior, with four groups including glass fiber, flax, sisal, and jute fibers. Pull-out behavior testing was conducted on twelve samples, divided into four groups of fiberglass, flax, sisal, and jute. Each group used three types of concrete: normal, high strength, and ultra-high-performance concrete (UHPC). The results refer to flax samples that had a higher tensile strength and elastic modulus of 143 MPa and 38 GPa, respectively, than samples made of sisal and jute fibres. The hybrid bars with a steel core exhibited a significant improvement in elastic modulus of 206 % in compared to samples made solely from glass, sisal, and jute fibers. On the other hand, the samples with UHPC showed the highest bond strength. The sample U-GFRP with ultra-high-performance concrete showed the highest bond strength 9.32 MPa, while the sample N-GFRP with normal concrete showed the lowest bond strength 5.87 MPa, respectively. However, this study suggests that hybridizing natural fibers can be a cost-effective and eco-friendly alternative to synthetic fibers.

Pull-out strength tests conducted on screw anchors in uncracked concrete substrates of the C25/30 class are presented in this article. The destructive force for anchor–concrete fasting was tested, and in the next step, the average pull-out strengths of screw anchors in concrete substrates with and without the addition of steel fiber were determined. Currently, the pull-out strengths of anchors in fiber-reinforced concrete substrates are defined as for unreinforced concrete substrates. Therefore, pull-out tests were performed for screw anchors in fiber-reinforced concrete substrates. Fiber contents of 10, 20, 30, and 50 kg/m3 were used. An increase in the load capacity of screw anchors in a fiber-reinforced concrete substrate was demonstrated in a pull-out test compared to base samples without fibers. The coefficient related to the actual fastening behavior of a screw anchor in the fiber-reinforced concrete substrate was determined. It was assumed that a coefficient of 13.10 should be adopted. This was the lowest value obtained for the load capacity in this study for screw anchors in a fiber-reinforced concrete substrate. [ABSTRACT FROM AUTHOR]

In this study, foam concretes (FCs) were developed, and their tension, shear, and bond properties were investigated for potential repair applications. Seven FC mixtures with varying combinations of ground granulated blast furnace slag (GGBS) and fly ash (FA) were prepared, along with one M25-grade conventional concrete mixture. The tension properties of both types of concrete were assessed through split tensile strength, flexural strength, and a pull-off test while the shear and bond strength (with reinforcing bars) were determined using the slant shear test and pull-out test, respectively. The results indicated that the compressive strength of the FC mixtures at 28 days ranged from 21.98 to 40.08 MPa, satisfying the requirements of IS 456: 2000 for M15 to M30-grade concrete. Furthermore, the split tensile strength of FC was in the range of 2.21 MPa to 2.83 MPa, while M25-grade concrete showed a strength of 2.24 MPa. Shear strength for FCs ranged between 6.67 MPa and 8.08 MPa while that of the M25-grade concrete was 5.49 MPa. Additionally, the tensile bond strength of FCs fell within the range of 0.67 MPa to 1.46 MPa while that of the M25-grade concrete was 1.12 MPa. The bond strength obtained from the pull-out test for FCs was observed to vary within the range of 11.87 MPa to 23.26 MPa while that of the M25-grade concrete was 14.14 MPa. FCs exhibited superior bond strength compared to M25-grade concrete with both the concrete substrate and reinforcing bars. It was also noted that the tension and bond strength of FC were linearly correlated with its compressive strength. Microstructure analysis indicated that macropores were isolated and discontinuous in all FC mixtures. The improvement in mechanical and bond properties was attributed to enhancements in the microstructure, and the ability of GGBS and FA particles to fill pores in the cementitious paste regions. In conclusion, FC developed using the GGBS and FA as substitutes for cement and sand, respectively showed promise as an alternative concrete repair material, with comparable or superior tensile and bonding properties compared to M25-grade concrete.

This study employs soft computing techniques, including artificial neural network (ANN) models and gene expression programming (GEP), to enhance the prediction of ultimate load in timber pull-out tests under varying environmental conditions. A comprehensive dataset of 202 samples in normal environmental conditions and 324 samples under harsh conditions was gathered. Distinct models were developed for each scenario, achieving commendable accuracies. The ANN performed at 0.91 under normal conditions and 0.99 under harsh conditions, while the GEP performed at 0.91 and 0.94, respectively. The study also predicted free end slip in timber pull-out tests using an ANN model with an accuracy of 0.97. The SHapley values technique was employed to assess the impact of features on the models, revealing specific influential features. In the prediction model for ultimate load under harsh conditions, the rod type was most influential, while under normal conditions, bonded length demonstrated the highest impact. Additionally, the duration of immersion feature had the most substantial effect on predicting free end slip. The final section compared predicted data with experimental values, showing a noteworthy correlation of over 60% between the predicted outputs and established models.

Objective To develop a novel semi‐cannulated lateral mass screw (SC‐LMS) for cervical posterior fixations and compare the fixation stability and safety of SC‐LMS with regular solid lateral mass screw (S‐LMS) in bone cement augmentation and pullout strength using fresh cadaveric cervical vertebrae. Methods The conventional multiaxial screw for cervical lateral mass fixation was modified to a cannulated screw with two lateral holes, used for bone cement injection in situ. Eight fresh human cervical vertebrae (C3, C4, and C5) were collected and used. μCT scan was performed to evaluate the bone quality of the lateral masses, including bone mineral density (BMD), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp). SCLMS or S‐LMS were randomly inserted into the paired cervical vertebrae and pulled out as a screw loosening model. These screws were reinserted in with bone cement augmentation, scanned by μCT to obtain the bone cement distribution along the screws, and pulled out to test the screw purchase strength. Results Fmax values exhibited strong positive correlations with the local BMD (𝑟 = 0.8640, p

AbstractA predictive finite element model was developed to investigate the best configuration of a fixation pins system consisting of two K-wires inserted in a synthetic model (Sawbones®) at different angles and secured to a connecting rod. Two key parameters were considered to determine the best configuration delivering the higher pull-out strength and lower pull-out length: the diameter and insertion angle. Results show that as the diameter and insertion angle increased, the pull-out force increased, while the pull-out length decreased. Results are successfully compared with available experimental data in literature. This model can be used as an alternative to experimental study. [ABSTRACT FROM AUTHOR]

Objective: To develop a novel semi‐cannulated lateral mass screw (SC‐LMS) for cervical posterior fixations and compare the fixation stability and safety of SC‐LMS with regular solid lateral mass screw (S‐LMS) in bone cement augmentation and pullout strength using fresh cadaveric cervical vertebrae. Methods: The conventional multiaxial screw for cervical lateral mass fixation was modified to a cannulated screw with two lateral holes, used for bone cement injection in situ. Eight fresh human cervical vertebrae (C3, C4, and C5) were collected and used. μCT scan was performed to evaluate the bone quality of the lateral masses, including bone mineral density (BMD), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp). SCLMS or S‐LMS were randomly inserted into the paired cervical vertebrae and pulled out as a screw loosening model. These screws were reinserted in with bone cement augmentation, scanned by μCT to obtain the bone cement distribution along the screws, and pulled out to test the screw purchase strength. Results: Fmax values exhibited strong positive correlations with the local BMD (푟 = 0.8640, p < 0.0001) and Tb.Th (푟 = 0.6795, p = 0.0038), whereas a negative correlation with Tb.Sp (푟 = −0.5567, p = 0.0251). A significant difference was observed between the Fmax before and after PMMA injection on the SC‐LMS side (p = 0.019). The SC‐LMS exhibited lower risk of cement leakage than S‐LMS after PMMA injection, and a positive correlation was observed between 퐹max and the distribution volumes on the SC‐LMS side. Conclusion: The novel SC‐LMS provides more robust fixation stability and is safer than the S‐LMS for PMMA augmentation, which may be related to the cement‐screw‐cement‐bone complex formation. [ABSTRACT FROM AUTHOR]

Clarifying the effect of each parameter of screw design on its fixation strength is critical in the development of any type of screw. The purpose of this study was to clarify the relationship between the thread depth and fixation strength of metal screws for cancellous bone. Nine types of custom-made screws with the only changed variable being the thread depth were manufactured. Other elements were fixed at a major diameter of 4.5 mm, a thread region length of 15 mm, a pitch of 1.6 mm, and a thread width of 0.20 mm. The pull-out strength and insertion torque of each screw were measured for each of two foam-block densities (10 or 20 pcf). The correlation between the thread depth of the screw and the mechanical findings were investigated with single regression analysis. Regardless of the foam-block density, the pull-out strength significantly increased as the thread depth increased from 0.1 mm to 0.4 mm; after that, the increase was more gradual (p < 0.01, respectively). The relationship between the thread depth and insertion torque was similar. In addition, the insertion torque tended to be more strongly affected by screw depth than the pull-out strength (2.6 times at 20 pcf and 1.4 times at 10 pcf). The pull-out strength of 4.5-mm-diameter metal screws in a cancellous bone model was found to be biphasic, although linearly correlated with the change in screw depth in both phases. The boundary of the correlation was 0.4 mm regardless of the density of the bone model, with the effect of screw depth on pull-out strength beyond that being small in comparison. [ABSTRACT FROM AUTHOR]

Due to the corrosion of fasteners by water-based preservatives, the preserved timber in outdoor environments can decrease the service life of the metal fasteners. In addition, the segregation of timber members and metal fasteners is also difficult during the demolition of timber structures. Wooden fasteners can be a promising alternative to metal fasteners because they have favorable resistance against corrosion and are more naturally harmonized with timber members. This paper studied the pull-out performance of dried densified wood (DW) dowels embedded into glued laminated timber (glulam) parallel to the grain with three different embedded lengths in two ambient environments with a temperature of 20°C and relative humidity (RH) of 65% and with a temperature of 20°C and relative humidity of 85%. The hygroscopic swelling of the dried DW dowels with a long embedded length can provide the favorable friction locking to transfer the axial load. [ABSTRACT FROM AUTHOR]

Monolateral pin-to-bar-clamp fixators are commonly used to stabilize acute extremity injuries. Certain rules regarding frame geometry have been established that affect construct stability. The influence of sagittal pin angulation on construct stiffness and strength has not been investigated. The purpose of this biomechanical study was to demonstrate the effect of a pin angulation in the monolateral fixator using a composite cylinder model. Three groups of composite cylinder models with a fracture gap were loaded with different mounting variants of monolateral pin-to-bar-clamp fixators. In the first group, the pins were set parallel to each other and perpendicular to the specimen. In the second group, both pins were set convergent each in an angle of 15° to the specimen. In the third group, the pins were set each 15° divergent. The strength of the constructions was tested using a mechanical testing machine. This was followed by a cyclic loading test to produce pin loosening. A pull-out test was then performed to evaluate the strength of each construct at the pin–bone interface. Initial stiffness analyses showed that the converging configuration was the stiffest, while the diverging configuration was the least stiff. The parallel mounting showed an intermediate stiffness. There was a significantly higher resistance to pull-out force in the diverging pin configuration compared to the converging pin configuration. There was no significant difference in the pull-out strength of the parallel pins compared to the angled pin pairs. Convergent mounting of pin pairs increases the stiffness of a monolateral fixator, whereas a divergent mounting weakens it. Regarding the strength of the pin–bone interface, the divergent pin configuration appears to provide greater resistance to pull-out force than the convergent one. The results of this pilot study should be important for the doctrine of fixator mounting as well as for fixator component design. [ABSTRACT FROM AUTHOR]

In this paper, cold-formed steel C-shaped connectors, as one of the most commonly used components in steel wall/framing systems, were investigated under the pull-out failure modes using a detailed numerical study. Finite element models were validated using the data obtained from an experimental program; and the results were compared with the current design equations. Finally, a new pull-out strength equation was proposed based on the critical parameters affecting the behaviour of C-shaped connectors. In addition, initial bending stiffness of C-shaped connectors was studied using a simplified analytical approach; and the results obtained from the proposed new stiffness equation were compared with the initial slope of experimental and numerical force-displacement curves. These comparisons confirm the accuracy of the new strength and stiffness equations in order to apply to the analytical methods such as component-based method in future works. [ABSTRACT FROM AUTHOR]

Rods glued into cross laminated timber – experiments, numerical simulation and load capacity prediction Timber construction is currently pushing new boundaries in terms of dimensions and architectural possibilities, as shown by the increasing number of high‐rise buildings. This is made possible by high‐performance connections, such as glued‐in rods (GiR, with rods made of steel and fibre reinforced polymers), and wood materials, such as cross‐laminated timber (CLT), which consists of several layers of boards glued flat and crosswise to each other, or glued‐laminated timber (GLT) where all layers are glued together in the same orientation. This paper highlights the current state of the art of GiR glued into CLT and gives an overview of recent experimental and numerical results. The similarities, but also the differences, between GiR glued into CLT and GLT, which result from the different orientation of the individual layers, are shown. Another focus is on the prediction of the connection load‐carrying capacity, for which only very few approaches are currently available. [ABSTRACT FROM AUTHOR]

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Objective : To analyze the effects of the number and shape of fenestrations on the mechanical strength of pedicle screws and the effects of bone cement augmentation (BCA) on the pull-out strength (POS) of screws used in conventional BCA. Methods : For the control group, a conventional screw was defined as C1, a screw with cannulated end-holes was defined as C2, a C2 screw with six pinholes was defined as C3, and the control group type was set. Among the experimental screws, T1 was designed using symmetrically placed thru-hole type fenestrations with an elliptical shape, while T2 was designed with half-moon (HM)-shaped asymmetrical fenestrations. T3 and T4 were designed with single HM-shaped fenestrations covering three pitches and five pitches, respectively. T5 and T6 were designed with 0.6-mm and 1-mm wider fenestrations than T3. BCA was performed by injecting 3 mL of commercial bone cement in the screw, and mechanical strength and POS tests were performed according to ASTM F1717 and ASTM F543 standards. Synthetic bone (model #1522-505) made of polyurethane foam was used as a model of osteoporotic bone, and radiographic examinations were performed using computed tomography and fluoroscopy. Results : In the fatigue test, at 75% ultimate load, fractures occurred 7781 and 9189 times; at 50%, they occurred 36122 and 82067 times; and at 25%, no fractures occurred. The mean ultimate load for each screw type was 219.1±52.39 N for T1, 234.74±15.9 N for T2, 220.70±59.23 N for T3, 216.45±32.4 N for T4, 181.55±54.78 N for T5, and 216.47±29.25 N for T6. In comparison with C1, T1, T2, T3, T4, and T6 showed significantly different ultimate load values (p<0.05). However, when the values for C2 and the fenestrated screws were evaluated with an unpaired t test, the ultimate load value of C2 significantly differed only from that of T2 (p=0.025). The ultimate load value of C3 differed significantly from those of T1 and T2 (C3 vs. T1 : p=0.048; C3 vs. T2 : p<0.001). Linear correlation analysis revealed a significant correlation between the fenestration area and the volume of bone cement (Pearson’s correlation coefficient r=0.288, p=0.036). The bone cement volume and ultimate load significantly correlated with each other in linear correlation analysis (r=0.403, p=0.003). Conclusion : Fenestration yielded a superior ultimate load in comparison with standard BCA using a conventional screw. In T2 screws with asymmetrical two-way fenestrations showed the maximal increase in ultimate load. The fenestrated screws can be expected to show a stable position for the formation of the cement mass. [ABSTRACT FROM AUTHOR]

Monolateral pin-to-bar-clamp fixators are commonly used to stabilize acute extremity injuries. Certain rules regarding frame geometry have been established that affect construct stability. The influence of sagittal pin angulation on construct stiffness and strength has not been investigated. The purpose of this biomechanical study was to demonstrate the effect of a pin angulation in the monolateral fixator using a composite cylinder model. Three groups of composite cylinder models with a fracture gap were loaded with different mounting variants of monolateral pin-to-bar-clamp fixators. In the first group, the pins were set parallel to each other and perpendicular to the specimen. In the second group, both pins were set convergent each in an angle of 15° to the specimen. In the third group, the pins were set each 15° divergent. The strength of the constructions was tested using a mechanical testing machine. This was followed by a cyclic loading test to produce pin loosening. A pull-out test was then performed to evaluate the strength of each construct at the pin–bone interface. Initial stiffness analyses showed that the converging configuration was the stiffest, while the diverging configuration was the least stiff. The parallel mounting showed an intermediate stiffness. There was a significantly higher resistance to pull-out force in the diverging pin configuration compared to the converging pin configuration. There was no significant difference in the pull-out strength of the parallel pins compared to the angled pin pairs. Convergent mounting of pin pairs increases the stiffness of a monolateral fixator, whereas a divergent mounting weakens it. Regarding the strength of the pin–bone interface, the divergent pin configuration appears to provide greater resistance to pull-out force than the convergent one. The results of this pilot study should be important for the doctrine of fixator mounting as well as for fixator component design.

Abstract Objective This research aimed to developing customized pedicle screw based on Indonesian vertebral anatomy and compare the insertion time, pull-out strength, and screw-media interface area of different screw design. We have developed 3 different types of pedicle screws (v-thread cylinder-core, square-thread cylinder-core and square-thread conical-core). The thread diameter was calculated from pedicle width of Indonesian population (6 mm). We used commercially available pedicle screw as control group (6.2 mm). Result The insertion time were significantly difference between v-thread cylinder-core pedicle screw (22.94 s) with commercially available pedicle screw (15.86 s) (p

Background Context: Therapeutic devices for spinal disorders, such as spinal fusion cages, must be able to facilitate the maintenance and rapid recovery of spinal function. Therefore, it would be advantageous that future spinal fusion cages facilitate rapid recovery of spinal function without secondary surgery to harvest autologous bone.Purpose: This study investigated a novel spinal cage configuration that achieves in vivo mechanical integrity as a devise/bone complex by inducing bone that mimicked the sound trabecular bone, hierarchically and anisotropically structured trabeculae strengthened with a preferentially oriented extracellular matrix.Study Design/settings: In vivo animal study.Methods: A cage possessing an anisotropic through-pore with a grooved substrate, that we termed "honeycomb tree structure," was designed for guiding bone matrix orientation; it was manufactured using a laser beam powder bed fusion method through an additive manufacturing processes. The newly designed cages were implanted into sheep vertebral bodies for 8 and 16 weeks. An autologous bone was not installed in the newly designed cage. A pull-out test was performed to evaluate the mechanical integrity of the cage/bone interface. Additionally, the preferential orientation of bone matrix consisting of collagen and apatite was determined.Results: The cage/host bone interface strength assessed by the maximum pull-out load for the novel cage without an autologous bone graft (3360±411 N) was significantly higher than that for the conventional cage using autologous bone (903±188 N) after only 8 weeks post-implantation.Conclusions: These results highlight the potential of this novel cage to achieve functional fusion between the cage and host bone. Our study provides insight into the design of highly functional spinal devices based on the anisotropic nature of bone.Clinical Significance: The sheep spine is similar to the human spine in its stress condition and trabecular bone architecture and is widely recognized as a useful model for the human spine. The present design may be useful as a new spinal device for humans. [ABSTRACT FROM AUTHOR]

Conventional insertion torque and pull-out tests are destructive and unsuitable for clinical bone screw fixation. This study evaluates screw stability using acoustic modal analysis (AMA) and Periotest compared to traditional methods in an ex vivo animal model. Titanium self-tapping screws (STS) and nonself-tapping screws (N-STS) were implanted in the proximal tibia of 12 rabbits. Four testing methods were used to assess screw stability: peak insertion torque (PIT) during implantation, AMA for natural frequency (NF), Periotest for Periotest value (PTV), and pull-out test for peak pullout force (PPF). Euthanization was performed at 0 (primary stability), 4, and 8 weeks (secondary stability). No significant difference in primary stability was found between STS and N-STS except for AMA (STS: NF 2434 ± 67 Hz, N-STS: NF 2572 ± 43 Hz; p = 0.62). Secondary stability increased significantly over time for both screw types (4-week: NF 3687 ± 36 vs. 3408 ± 45 Hz, PTV 1.4 ± 1.6 vs. -1.5 ± 1.8, PPF 236 ± 29 vs. 220 ± 34 N; 8-week: NF 3890 ± 39 vs. 3613 ± 31 Hz, PTV -3.2 ± 2.5 vs. -2 ± 4.3, PPF 248 ± 25 vs. 289 ± 28 N). Higher NF values for given PTV/PPF indicate potential clinical advantages. Significant differences between primary and secondary stabilities suggest osteointegration was mainly achieved in the 4-week group., (© 2024 The Author(s). Journal of Orthopaedic Research® published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society.)

Plate fixation has recently gained popularity among the various surgical methods used to treat Neer type II distal clavicle fractures. The use of a low‐profile distal clavicle locking plate is logically considered a better option when there is no significant difference in the fixation strength between insertions of 3.5‐ and 2.7‐mm diameter screws. Therefore, the purpose of this biomechanical study was to investigate any differences in fixation strength among varying sizes of screws that are used to treat distal clavicle fractures. The study was performed with 20 paired shoulder girdles from 10 fresh frozen cadavers. To create a type IIA fracture of Neer classification, osteotomy was performed perpendicularly to the longitudinal axis of the clavicle at the medial end point of the conoid ligament. Two custom‐made fixtures designed to be attached to both upper and lower sides of the Instron were fabricated for the evaluation. The mean maximum pull‐out strength for fixation using 3.5‐mm diameter screws was 241.9 ± 67.8 N, whereas the mean pull‐out strength in fixation with 2.7‐mm diameter screws was 228.1 ± 63.0 N. There was no statistically significant difference between the two groups. Distal fragment fixation with distal clavicle locking plates using two 2.7‐mm diameter screws showed comparable biomechanical pull‐out strength at the time‐zero setting to fixations with a hook plate using two 3.5‐mm diameter screws. Therefore, the fixation of the distal fragment with a low‐profile plate and 2.7‐mm screws may be preferred as an alternative option if the distal fragment of the fractured clavicle is not extremely small. [ABSTRACT FROM AUTHOR]

Purpose: Meniscal surgery is one of the most common orthopaedic surgical interventions. Total meniscus replacements have been proposed as a solution for patients with irreparable meniscal injuries. Reliable fixation is crucial for the success and functionality of such implants. The aim of this study was to characterise an interference screw fixation system developed for a novel fibre-matrix-reinforced synthetic total meniscus replacement in an ovine cadaveric model. Methods: Textile straps were tested in tension to failure (n = 15) and in cyclic tension (70–220 N) for 1000 cycles (n = 5). The textile strap-interference screw fixation system was tested in 4.5 mm-diameter single anterior and double posterior tunnels in North of England Mule ovine tibias aged > 2 years using titanium alloy (Ti6Al4Va) and polyether-ether-ketone (PEEK) screws (n ≥ 5). Straps were preconditioned, dynamically loaded for 1000 cycles in tension (70–220 N), the fixation slippage under cyclic loading was measured, and then pulled to failure. Results: Strap stiffness was at least 12 times that recorded for human meniscal roots. Strap creep strain at the maximum load (220 N) was 0.005 following 1000 cycles. For all tunnels, pull-out failure resulted from textile strap slippage or bone fracture rather than strap rupture, which demonstrated that the textile strap was comparatively stronger than the interference screw fixation system. Pull-out load (anterior 544 ± 119 N; posterior 889 ± 157 N) was comparable to human meniscal root strength. Fixation slippage was within the acceptable range for anterior cruciate ligament graft reconstruction (anterior 1.9 ± 0.7 mm; posterior 1.9 ± 0.5 mm). Conclusion: These findings show that the textile attachment-interference screw fixation system provides reliable fixation for a novel ovine meniscus implant, supporting progression to in vivo testing. This research provides a baseline for future development of novel human meniscus replacements, in relation to attachment design and fixation methods. The data suggest that surgical techniques familiar from ligament reconstruction may be used for the fixation of clinical meniscal prostheses. [ABSTRACT FROM AUTHOR]

Using barbed thread lifting for facial rejuvenation has become popular these days due to its minimally invasive procedures with reduced complications. However, only limited studies regarding its mechanical properties for face suspension were published. The aim of this study was to evaluate suture-holding ability regarding its facelift property, and different specimens were tested in order to establish an in vitro model. Fresh porcine tissue and the synthetic material polydimethylsiloxane (PDMS) were selected to simulate human skin for evaluating barbed suture pull-out strength by the universal material testing machine. The results showed that the pull-out strength of barbs between different porcine tissues varied without consistency. By contrast, PDMS (30:1) showed more consistent pull-out strength in each testing, and the average maximum load force was close to porcine tissue. Furthermore, after submerging barbed sutures in PBS for 0 days (T0), 7 days (T7) and 14 days (T14), a trend of decreased average maximum load force, displacement and force of 1.5 mm/2 mm/3 mm displacement could be detected by in vitro testing with PDMS (30:1). These results provide support for using PDMS (30:1) to evaluate suture pull-out strength and holding/lifting capacities in vitro to obtain consistent and objective information for evaluating substantial equivalence of devices. The established in vitro method could be used for the future development of barbed thread lifting technology. [ABSTRACT FROM AUTHOR]

To evaluate the effect of the placement angle, diameter, length and bone density on the mechanical stability of orthodontic mini-implants by measuring their pull-out strengths. A total of 120 mini-implants of four different dimensions made from titanium were used. They measured 1.3 × 6.0mm, 1.3 × 8.0 mm, 1.5 × 6.0 mm and 1.5 × 8.0 mm. Synthetic polyurethane bone blocks (Saw Bones, USA) in two different densities were used. Each size of mini-implant was inserted equidistantly into synthetic bone blocks of two different densities, in three different insertion angles of 30°, 60° and 90°. This resulted in 24 test groups with five mini-implants allocated to each group. The pull-out strength was measured using an Instron Universal Testing Machine exerting a vertical force parallel to the long axis of the mini-implant until removal or failure occurred. Peak load at failure of the mini-implant was recorded in kN. Showed that mini-implants placed at an insertion angle of 30° offered least resistance to pull-out. Mini-implants 6.0 mm in length showed less pull-out strength compared to the longer 8.0-mm mini-implants. Mini-implants 1.3 mm in diameter provided similar pull-out values as 1.5-mm mini-implants. Bone densities of 0.20 g/cc and 0.32 g/cc did not affect the pull-out strength of mini-implants. From the study, it was concluded that a logical choice of mini-implant dimension and prudent use of placement technique can help achieve the treatment goals with a reduced hazard of mini-implant failure. [ABSTRACT FROM AUTHOR]

Sheet-tube connection structures are widely applied in chemical, petroleum, medicine, and other industries. Its reliable connection and manufacturing are of great significance for the function of the corresponding equipment. To avoid the occurrence of too deep pits and easy warpage during the single-sided annular sheet squeezing process, an improved method to join sheets to tubes by double-sided annular sheet squeezing is proposed in this paper. The joining process is to squeeze the sheet through the top and bottom dies simultaneously, resulting in radial metal plastic flow, forming the interlock between the sheet and the tube. By experimental and numerical simulation, the joining process of Al6061-T6 sheet and tube under different process parameters using double- and single-sided annular sheet squeezing was conducted and compared. The pull-out test is used to evaluate the quality of sheet-tube joints. Results showed that using the double-sided annular sheet squeezing method can obtain a symmetrical interlocking structure rather than an asymmetric structure by single-sided squeezing, effectively reducing the pit depth on the sheet surface. In addition, the improved method can effectively reduce about 25% of the joining force, but the pull-out strength is about 1.5kN lower than that obtained by the single-sided squeezing method. The joining strength is comprehensively affected by the thickness of the die annulus, punch stroke, and squeezing type. The influence mechanism of process parameters on pull-out strength is discussed. This study provides a new and efficient joining way for the manufacture of sheet-tube connection structures. [ABSTRACT FROM AUTHOR]

The article presents a study on the pulling-out bearing capacity of the connection between a curtain wall system and an outer sheet of a wall sandwich panel with a mineral wool core realized through blind rivets. An experimental study was carried out on samples of sandwich panels with various parameters of fastening in order to assess the influence of the considered factors on the value of bearing capacity. Results obtained for the studied type of sandwich panel allowed us to determine the minimum permissible edge distance for a blind rivet in order to prevent delamination of the outer sheet as well as the influence of the end profile installation and cyclic load action on the bearing capacity of the joint. Experimental results showed that the edge distance of 75 mm or more does not affect the bearing capacity of the joint. The pulling-out bearing capacity of a blind rivet with a diameter of 4.8 mm was determined for both single and cyclic load actions. The presence of an additional stiffening element such as end face profile contributed to an increase of this value. Recommended scheme for the installation of the fastening elements was proposed based on dependencies obtained during the experimental investigation.

Objective: This research aimed to developing customized pedicle screw based on Indonesian vertebral anatomy and compare the insertion time, pull-out strength, and screw-media interface area of different screw design. We have developed 3 different types of pedicle screws (v-thread cylinder-core, square-thread cylinder-core and square-thread conical-core). The thread diameter was calculated from pedicle width of Indonesian population (6 mm). We used commercially available pedicle screw as control group (6.2 mm). Result: The insertion time were significantly difference between v-thread cylinder-core pedicle screw (22.94 s) with commercially available pedicle screw (15.86 s) (p < 0.05). The pull-out strength was significantly difference between commercially available pedicle screw (408.60 N) with square-thread conical pedicle screw (836.60 N) (p < 0.05). The square-thread conical-core group have the highest interface area (1486.21 mm2). The data comparison showed that the square-thread conical-core customized pedicle screw group has comparable insertion time and has better pull-out strength than commercially available pedicle screw. [ABSTRACT FROM AUTHOR]

Objective This study aimed to investigate the strength of a novel micro‐dynamic pedicle screw by comparing it to the traditional pedicle screw. Methods Forty‐five lumbar vertebrae received a traditional pedicle screw on one side and a micro‐dynamic pedicle screw on the other side as follows (traditional group vs micro‐dynamic group): 15 vertebrae underwent instant pull‐out testing; 15 vertebrae underwent 5000‐cyclic fatigue loading testing; and 15 vertebrae underwent 10,000‐cyclic fatigue loading testing and micro‐computed tomography (micro‐CT) scanning. The peek pull‐out force and normalized peek pull‐out force after instant pull‐out testing, 5000‐cyclic and 10,000‐cyclic fatigue loading testing were recorded to estimate the resistance of two types of screws. Bone mineral density was recorded to investigate the strength of the different screws in osteoporotic patients. And the semidiameter of the screw insertion area on micro‐CT images after fatigue were compared to describe the performance between screw and bone surface. Results The bone mineral density showed a weak correlation with peek pull‐out force (r = 0.252, P = 0.024). The peek pull‐out force of traditional pedicle screw after 10,000‐cyclic fatigue loading were smaller than that of instant pull‐out test in both osteoporotic (P = 0.017) and healthy group (P = 0.029), the peek pull‐out force of micro‐dynamic pedicle screw after 10,000‐cyclic fatigue loading was smaller than that in instant pull‐out test in osteoporotic group (P = 0.033), but no significant difference in healthy group (P = 0.853). The peek pull‐out force in traditional group and micro‐dynamic group underwent instant pull‐out testing (P = 0.485), and pull‐out testing after 5000‐cyclic fatigue loading testing (P = 0.184) did not show significant difference. However, the peek pull‐out force in micro‐dynamic group underwent pull‐test after 10,000‐cyclic fatigue loading testing was significantly greater than that measured in traditional group (P = 0.005). The normalized peek pull‐out force of traditional groups underwent instant pull‐out testing, pull‐out test after 5000‐cyclic and 10,000‐cyclic fatigue loading testing significantly decreased as the number of cycles increased (P

As an important method for connecting structural members, anchor bolts have been installed in many situations. Therefore, accurate evaluation of the pull-out strength of anchor bolts has always been an important issue, considering the complicated actual installation conditions and the problem of aging deterioration of the structural members. In general, the patterns of pull-out failure of anchor bolts can be classified into three types: adhesion failure, cone failure, and bolt break. However, it sometimes shows a mixed fracture pattern, and it is not always easy to predict the accurate pull-out strength. In this study, we attempted to evaluate the pull-out strength of anchor bolts under various installation conditions using SPH, which can analyze the crack growth process in the concrete. In particular, the anchor bolt-concrete interface model was introduced to SPH analysis in order to consider the bond failure, and it was confirmed that various failure patterns and the load capacity could be predicted by proposed SPH method. After that, the influence of several parameters, such as bond stress limit, anchor bolt diameter, and the anchor bolt embedment depth on the failure patterns and the load capacity, were investigated by numerical calculation. Furthermore, several useful suggestions on the pull-out strength of anchor bolts under improper installation conditions, such as the ends of members for the purpose of seismic retrofitting, are presented. [ABSTRACT FROM AUTHOR]

This study aims to examine the relation between pull-out strength and preload values of the cortical screw used in bone fracture fixation. The research question is that "Does the pull-out strength of the cortical screw used in the bone fracture fixation change with the preload values of the screw change?". To perform this purpose, the finite element method was selected due to its ease to evaluate and calculate the stresses on the whole model. Models of a cortical screw, partial plate, and bone were created using the SolidWorks program. The material properties of the bone were selected orthotropic material type. The bone fixed on the distal and proximal ends. The pull-out forces were applied at the bottom of the plate. The screw that has been loaded ranges from 100 N-700 N as preload. The pull-out forces were determined 200-400-600 N as in the literature. The results show that the pull-out strength of the screw was changed when the preloaded values higher than 400 N. However, it was seen that the pull-out strength does not substantially change when the preload values were lower than 400 N. When the preload values were applied =500 N, the maximum von Mises stresses on the screw exceeded the critical strength of the screw material. In conclusion, the critical preload value was determined as 500 N for the optimum pull-out strength. [ABSTRACT FROM AUTHOR]

In this research work, the bonding characteristics of plasma treated basalt fibres were analysed by employing the fibre pull-out test. 80 samples were prepared with two different spans of basalt fibres (such as 25 mm and 50 mm) and four levels of embedded length (10, 15, 20 and 25) inside standard M20 grade concrete. Debonding and bonding characteristics of the plasma treated fibres were compared with raw basalt fibres through the fibre pull-out test. The plasma treated and raw basalt fibres were characterised through Field emission scanning electron microscope (FESEM) and Fourier transform infrared (FTIR) analysis. It was observed that confirmation of the presence of hydroxyl groups on the basalt fibre surface was realised through the FTIR test and that there was higher adsorption of concrete particles by the plasma treated basalt fibres through FESEM. The de bonding and fibre pull-out energy of the plasma treated basalt fibres were improved by about 9% and 10% compared with 25 mm and 50 mm raw basalt fibres. From the observation above, it can be stated that the surface modification of basalt fibre may lead to a change in the debonding and pull-out energy level. [ABSTRACT FROM AUTHOR]

Pedicle bone screws are one of the most critical materials used in spinal orthopaedic operations. Screw loosening and pull-out (PO) are basic complications encountered during or after surgery. Pull-out Strength (POS) of the bone is one of the significant parameters to understand the mechanical behaviour of a screw fixed to poor quality or osteoporotic bone. This study investigates how the POS of a pedicle screw is affected by the factors of the screw diameter and the polyurethane (PU) foam density by experimental analysis. In the experiments, two different diameter (5.5 and 6.5 mm) of conical pedicle screws and five different density (0.08, 0.16, 0.24, 0.32 and 0.48 g·cm-3) PU foams were used. According to the force-displacement curves obtained from experimental results, the POS increased with the increases in screw diameter and PU foam density. [ABSTRACT FROM AUTHOR]

This paper investigated the potential applicability of the specification equation for the shear pull-out strength of a power-actuated fastener (PAF) connection to nail connections between steel sheets thinner than 2.9 mm. The tested G300, G450, and G550 specimens had thicknesses ranging from 0.6 to 2.4 mm, connected with 2.5- or 3.6-mm helically knurled nails. The pull-out strength is a function not only of the thickness of the member not in contact with the fastener head, but also of the other member's thickness. The member thicknesses have greater influence than the nail diameter on the pull-out strength, contrary to the design equation. Based on the test results of 93 shear nailed connections failing in pull-out, the paper proposes a design equation that is applicable to connections using helically knurled nails of steel sheets thinner than 2.9 mm. A group effect factor of 0.75 is suggested for serial nail connections based on the test results of 19 multiple nail connections. A resistance factor of 0.55 is recommended for use with the proposed equation for determining the pull-out strength of shear nailed connections in thin steel sheets. An additional finding is that the current design equation for the bearing and tilting strength of a PAF connection is applicable to connections in which the member not in contact with the fastener head is much thinner than the specification minimum of 3.2 mm, and in which the fastener diameter is smaller than the specification minimum of 3.7 mm. [ABSTRACT FROM AUTHOR]

Under the combined effects of heavy traffic loading and extreme environmental conditions, the failure issues of repaired potholes caused by insufficient interfacial bonding strength between the new and old pavement materials occur frequently, which severely impairs the durability of the repaired structure. This study aims to improve the interfacial bonding strength between the new and old pavement materials and prolong the service life of repair pothole materials. Firstly, the mechanical analysis was carried out using finite element simulation, and a technical measure was proposed to ensure improved interfacial bonding strength between new and old pavement materials. Secondly, emulsified asphalt (EA), light asphalt (LA), waterborne epoxy resin-modified emulsified asphalt (WER-EA) and silicone penetrant (SP) were selected to investigate the paving workability, viscosity changing and curing times of bonding materials at different temperatures. On this basis, the interlaminar shear and pull-out tests were performed under different paving mass, temperatures and humidity conditions, and the shear and pull-out strengths of four bonding materials were compared to optimize the type and paving mass of interface bonding material. The results show that an increase in bonding coefficient (BC) significantly reduces the values of pressure stress (σ y) and pressure strain (ε y), even the bucking depth of the pothole sides, thus decreasing the risk of pothole repair failure. Under normal or low-temperature conditions and field construction, SP has exceptional paving workability, and its shear and pull-out strengths are much higher than other bonding materials, with an optimum paving mass rate being 0.3 kg/m2 ∼ 0.4 kg/m2. The research results are of great significance in improving the pothole repairing level, standardizing the repair process and extending the service life of pavements. • Superior bonding strengthextends the service life of repair pothole materials. • Abaqus software is employed to analyze the mechanical response and suggest measures to avoid pothole repair failure. • An increase in BC reduces the values of σy and εy, even the bucking depth of the pothole sides. • Silicone penetrant has exceptional paving workability and bonding strengths. [ABSTRACT FROM AUTHOR]

Using barbed thread lifting for facial rejuvenation has become popular these days due to its minimally invasive procedures with reduced complications. However, only limited studies regarding its mechanical properties for face suspension were published. The aim of this study was to evaluate suture-holding ability regarding its facelift property, and different specimens were tested in order to establish an in vitro model. Fresh porcine tissue and the synthetic material polydimethylsiloxane (PDMS) were selected to simulate human skin for evaluating barbed suture pull-out strength by the universal material testing machine. The results showed that the pull-out strength of barbs between different porcine tissues varied without consistency. By contrast, PDMS (30:1) showed more consistent pull-out strength in each testing, and the average maximum load force was close to porcine tissue. Furthermore, after submerging barbed sutures in PBS for 0 days (T0), 7 days (T7) and 14 days (T14), a trend of decreased average maximum load force, displacement and force of 1.5 mm/2 mm/3 mm displacement could be detected by in vitro testing with PDMS (30:1). These results provide support for using PDMS (30:1) to evaluate suture pull-out strength and holding/lifting capacities in vitro to obtain consistent and objective information for evaluating substantial equivalence of devices. The established in vitro method could be used for the future development of barbed thread lifting technology.

The article presents the pull-out strength tests carried out on M10 expansion anchors in non-cracked and cracked concrete with a crack width cw = 0.30 mm. The breaking loads and the average pull-out strength of anchors in fibre-reinforced concrete substrates were determined. Fibre content ratios of 15, 30 and 50 kg/m3 were used. In addition, two different classes of concrete (C20/25 and C50/60) were tested. The addition of steel fibres caused a decrease in the pull-out strength by 5% for non-cracked concrete of C20/25 class and fibre content up to 30 kg/m3 and a further 7% for the remaining specified dosage. While for concrete of the C50/60 class, it a decrease in the pull-out strength of up to 20% was observed. For cracked concrete class C20/25 with crack initiation cw = 0.30 mm, the reduction was from 9% to 16% in relation to non-cracked concrete and a maximum of 18% for the fibre content of 50 kg/m3. The difference between the tensile load capacity of C50/60 class cracked and non-cracked concrete was lower than 5% and fell within the measurement error.

Background: We hypothesized that an entire pedicle screw tract cement augmentation has greater strength than traditional techniques. Method: Twenty-four fresh frozen calf lumbar spines were randomized into three study groups, each having eight vertebrae: (1) screw cemented after vertebroplasty; (2) fenestrated cemented screw; and (3) cementation of the entire pedicle screw tract. For the right side screws, two pedicle screws were inserted in each vertebra with the standard position in the sagittal plane, whereas the left side screws were placed at a 30° angle craniocaudal plane. From the recorded force–displacement curves, the maximum peak load (failure load) of each screw was determined. The mode of failure was screw stripping at all levels tested. Results: The pull-out strength for standard screw replacement at the sagittal plane was 1843.3 N, 1707.45 N, and 5365.1 N consecutively. The failure load value in the standard position in the sagittal plane in the cementation of the entire pedicle screw tract group was significantly higher than that in the fenestrated cemented screw group and screw cemented after vertebroplasty (p < 0.001 and p < 0.001, respectively). The standard pedicle screw position in the sagittal plane showed a significant pull-out strength than the others (p < 0.001). Conclusion: The pull-out strength of the cementation of the entire pedicle screw tract was 2.5 times higher than the others. The pull-out strength of the pedicle screws in malposition obtained the same strength to the standard positions after the augmentation procedure in our study. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate the strength of a novel micro‐dynamic pedicle screw by comparing it to the traditional pedicle screw. Methods: Forty‐five lumbar vertebrae received a traditional pedicle screw on one side and a micro‐dynamic pedicle screw on the other side as follows (traditional group vs micro‐dynamic group): 15 vertebrae underwent instant pull‐out testing; 15 vertebrae underwent 5000‐cyclic fatigue loading testing; and 15 vertebrae underwent 10,000‐cyclic fatigue loading testing and micro‐computed tomography (micro‐CT) scanning. The peek pull‐out force and normalized peek pull‐out force after instant pull‐out testing, 5000‐cyclic and 10,000‐cyclic fatigue loading testing were recorded to estimate the resistance of two types of screws. Bone mineral density was recorded to investigate the strength of the different screws in osteoporotic patients. And the semidiameter of the screw insertion area on micro‐CT images after fatigue were compared to describe the performance between screw and bone surface. Results: The bone mineral density showed a weak correlation with peek pull‐out force (r = 0.252, P = 0.024). The peek pull‐out force of traditional pedicle screw after 10,000‐cyclic fatigue loading were smaller than that of instant pull‐out test in both osteoporotic (P = 0.017) and healthy group (P = 0.029), the peek pull‐out force of micro‐dynamic pedicle screw after 10,000‐cyclic fatigue loading was smaller than that in instant pull‐out test in osteoporotic group (P = 0.033), but no significant difference in healthy group (P = 0.853). The peek pull‐out force in traditional group and micro‐dynamic group underwent instant pull‐out testing (P = 0.485), and pull‐out testing after 5000‐cyclic fatigue loading testing (P = 0.184) did not show significant difference. However, the peek pull‐out force in micro‐dynamic group underwent pull‐test after 10,000‐cyclic fatigue loading testing was significantly greater than that measured in traditional group (P = 0.005). The normalized peek pull‐out force of traditional groups underwent instant pull‐out testing, pull‐out test after 5000‐cyclic and 10,000‐cyclic fatigue loading testing significantly decreased as the number of cycles increased (P < 0.001); meanwhile, the normalized peek pull‐out force of micro‐dynamic groups remained consistent regardless of the number of cycles (P = 0.133). The semidiameter after the fatigue loading test of the traditional screw insertion area was significantly larger than that of the micro‐dynamic screw insertion area (P = 0.013). Conclusion: The novel micro‐dynamic pedicle screw provides stronger fixation stability in high‐cyclic fatigue loading and non‐osteoporotic patients versus the traditional pedicle screw, but similar resistance in low‐cycle fatigue testing and osteoporotic group vs the traditional pedicle screw. [ABSTRACT FROM AUTHOR]

As an effective energy-absorbing cable, constant resistance large deformation (CRLD) cables have been widely applied in rock engineering projects; however, to the best of our knowledge, its interaction mechanism with the surrounding rock has never been studied. According to previous practical projects, the CRLD cable–rock interaction differs from that of conventional cables because of the tubular expansion during the CRLD process, and it influences the performance of the cable reinforcement system. Therefore, an attempt was made to investigate the characteristics of the CRLD cable–rock interaction under static pull-out loading by using a coupled numerical method. The structure of the CRLD cable was modelled via the finite-difference method, and the surrounding rock was modelled via the discrete-element method. The micro-parameters of the surrounding rock were carefully calibrated, and the macro-parameters of the CRLD cable were verified by comparing them with a corresponding experimental test in the laboratory. The numerical results were carefully analysed. The constant resistance forces of a single CRLD cable and a CRLD cable reinforcement system were compared. The distribution of the normal and shearing stresses on the cable–rock interface was obtained, and the evolution mode of the pull-out strength was examined. In addition, the failure mode of the grouting material and surrounding rock was studied on a micro-scale. The findings describe the interaction of the CRLD cable against the surrounding rock, reveal its special anchorage mechanism, and can be used to predict and improve the performance of the CRLD cable reinforcement system. [ABSTRACT FROM AUTHOR]

Soil nailing as a construction practice has turned into a prime earth retention and slope stabilization technique. Present study undertakes potential parametric optimization in soil nailing by considering soil nail interaction and back analysis of the pull-out strength of nail using Finite Element Analysis using PLAXIS 2D. Results suggested pull-out strength as a function of depth, thereby providing a potential scope for optimization of soil nail length pattern. The observed trend of results has been further validated using Limit Equilibrium Analysis. Further, dynamic analysis was undertaken to ensure the seismic stability considering the reduced nail length pattern using FHWA guidelines and the numerical approaches like finite element and limit equilibrium methods. Results suggest that the observed trend with reduced nail length patterns caused mild increment in the serviceability conditions like horizontal deformation, but the results were observed to be within permissible limits in the ultimate limit state. Furtherance to the numerical analyses, a numerical regression analysis was undertaken to develop a correlation between the geotechnical parameters, nail length patterns and the limit conditions. [ABSTRACT FROM AUTHOR]

Featured Application: The study is to develop a surgical pedicle screw for the treatment of degenerative disc disease. With the recent increase in the elderly population, many people suffer from spinal diseases, and, accordingly, spinal fusion surgery using pedicle screws has been widely applied to treat them. However, most research on pedicle screw design has been focused on the test results rather than the behavior of the screws and vertebrae. In this study, a design platform with a series of biomechanical tests and analyses were presented for pedicle screw improvement and evaluation. The platform was then applied to an alternative hybrid screw design with quadruple and double threads. An experimental apparatus was developed to investigate the bending strength of the screw, and several tests were performed based on the ASTM F1717 standard. In the experiments, it was confirmed that the alternative pedicle screw has the highest bending strength. To examine the stress distribution of pedicle screws, finite element models were established, through which it was found that the proposed pedicle screw has sufficient mechanical safety to make it acceptable for spinal fusion treatment. Finally, we conclude that the platform has good potential for the design and evaluation of pedicle screws, and the alternative dual screw design is one of the best options for spinal fusion surgery. [ABSTRACT FROM AUTHOR]

• Screw contact area is in relation to pull-out strength. • Degree of bone compacting is in relation to insertion torque. • Thread design parameter d d can qualitatively predict pull-out strength. • Product of diameter and insertion torque can qualitatively predict pull-out strength. Pedicle screw loosening is still observed in clinical practice. Therefore, the understanding of the interaction between screw and bone is evermore subject of research. However, complex relationships between screw design and anchorage are rarely examined. For this reason, it is investigated whether screw fixation is predictable by a parameter that maps the thread. Two types of pedicle screws, 6.5 mm and 7.5 mm in major diameter, respectively, are pulled out from synthetic polyurethane foam. Representative design parameters were evaluated with regard to their influence on the insertion torque and pull-out strength. A correlation between the insertion torque and the degree of compacting of the bone was observed. In addition, the pull-out strength was found to be related to the contact area of the bone-screw interface, the bone volume displaced during screwing, and the displaced diameter. The relationship between insertion torque and pull-out strength was also linear. In addition, a relational equation was derived for the pull-out strength versus the insertion torque with the major diameter as scaling factor. Thus, the pull-out strength from cancellous bone is predictable by a representative design parameter. Furthermore, the derived relation equation opens a new perspective for the evaluation of screw fixation. [ABSTRACT FROM AUTHOR]

As an important method for connecting structural members, anchor bolts have been installed in many situations. Therefore, accurate evaluation of the pull-out strength of anchor bolts has always been an important issue, considering the complicated actual installation conditions and the problem of aging deterioration of the structural members. In general, the patterns of pull-out failure of anchor bolts can be classified into three types: adhesion failure, cone failure, and bolt break. However, it sometimes shows a mixed fracture pattern, and it is not always easy to predict the accurate pull-out strength. In this study, we attempted to evaluate the pull-out strength of anchor bolts under various installation conditions using SPH, which can analyze the crack growth process in the concrete. In particular, the anchor bolt-concrete interface model was introduced to SPH analysis in order to consider the bond failure, and it was confirmed that various failure patterns and the load capacity could be predicted by proposed SPH method. After that, the influence of several parameters, such as bond stress limit, anchor bolt diameter, and the anchor bolt embedment depth on the failure patterns and the load capacity, were investigated by numerical calculation. Furthermore, several useful suggestions on the pull-out strength of anchor bolts under improper installation conditions, such as the ends of members for the purpose of seismic retrofitting, are presented.

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The purpose of this study was to investigate the rate of pull-out strength gain of an etched titanium implant surface. Rabbit tibiae were used to compare machined titanium and proprietary dual-etched titanium implants. Two custom cylindric implants (3 mm in diameter and 4 mm in length) were placed in each right anteromedial tibia in 31 rabbits. At weeks 1, 2, 3, 4, 5, and 8, the implants in 5 rabbits were subjected to failure shear loading in a pull-out test. For shear failure testing, each tibial segment was mounted in a precision alignment jig, and an Instron pull-out test was performed on each implant. Beginning at week 3, there was a statistically significant difference (P < .01) between the dual-etched and the machined implants. There was a significant increase in strength for dual-etched implants between week 5 and week 8, while the machined implants did not show an increase during this time interval. The etched implants maintained a significantly greater pull-out strength for the remainder of the study, with a 3.2-fold greater mean strength at 8 weeks, equivalent to 6 months in humans. At 3 weeks, the etched implant's strength exceeded the strength that the machined implant had achieved at 8 weeks. In short-term healing in the rabbit tibia, the dual-etched surface demonstrated a more rapid rate of pull-out strength gain than the machined surface and remained significantly stronger throughout the 8 weeks of the study. [ABSTRACT FROM AUTHOR]

• Effect of seawater on pull-out behavior of glued-in rod timber joints is evaluated. • Strength degradation of joints built with steel rod is more than those with GFRP rod. • Dominant failure mode due to exposure to seawater is at the adhesive/wood interface. • Empirical models predicting the load-carrying capacity of joints are proposed. This paper experimentally investigates the effects of seawater on pull-out behavior of single rods glued in timber parallel to grain. Considering different rod diameters (6, 8, 10 mm), slenderness ratios (7.5, 10, 15), rebar materials (steel and GFRP), and immersion time in seawater (0, 10, 20, 30, 60, 90 days), 324 specimens were tested. Mean strength reduction about 39 and 55 percent was observed for 90-day immersed joints constructed with GFRP and steel rebars, respectively. Rebar diameter and slenderness ratio significantly influenced ultimate loads, and dominant failure mode was at adhesive/timber interface. Finally, two novel strength models were developed empirically. [ABSTRACT FROM AUTHOR]