Force Deformation Research Articles

Anatomy of the Flexor Hallucis Longus and Its Relationship With Hallux Valgus: A Cadaveric Study.

Hallux valgus (HV) is a complex deformity, with many associated risk factors. The flexor hallucis longus (FHL) tendon is a dynamic and potentially deforming force as it bowstrings laterally with HV. We hypothesized that FHL is more laterally inserted in the distal phalanx in cadavers with HV; therefore, it might be also a primary destabilizing force. We aim to compare the FHL distal insertion morphology and its relationship with osseous structures in cadavers with and without HV. Sixteen cadaver specimens, 8 with HV and 8 without (N-HV) were dissected. We evaluated FHL distal morphology in terms of its insertional footprint location and FHL long-axis position in relation to osseous anatomy. Both the HV and N-HV groups displayed a laterally inserted footprint at the distal phalanx, with the HV group exhibiting median lateral translation of the footprint 6% greater than the N-HV group (P < .01). Both groups also demonstrated a laterally displaced position for the FHL long axis. The median FHL long axis for HV vs N-HV specimens 1 cm proximal to the IP joint was 9% more laterally displaced from the midaxis (P < .01), and at 1 cm proximal to the MTP joint was measured to be 15% more laterally displaced from the midaxis (P < .01). FHL demonstrated an eccentric position in terms of insertion and trajectory in both the HV and N-HV groups, with greater lateralization in specimens exhibiting HV deformity. This eccentricity potentially creates a greater deforming force vector contributing to the development of HV. The etiology and progression of HV deformity may include a lateralized insertion of the FHL tendon. Treatment implications remain unknown at this time.

Model tests and numerical simulations of deformation repair effect for operating shield tunnels under horizontal lateral grouting

To address the large deformation problem of operating straight-joint assembled shield tunnels in soft soil, horizontal lateral grouting is often used. Using an independently designed and developed lateral grouting test device, a horizontal lateral grouting model test was conducted to study the tunnel force state and deformation repair law under the action of lateral grouting. The mechanical responses of tunnel under single-hole grouting (SHG) and two double-holes grouting (DHG) cases were comparatively analyzed, and the test results were further validated via numerical simulations. The results indicate that several key indicators of tunnel behavior, including additional pressure, bending moment, radial displacement, convergence deformation, and ellipticity, exhibit a positive correlation with the grouting volume and a negative correlation with the distance to the grouting point when implementing SHG. Expect for radial displacement, all of these metrics caused by DHG were greater than those caused by SHG. The horizontal radial displacement increases under same-side DHG but decreases under different-side DHG. Interestingly, same-side DHG is more favorable for reducing internal force and repairing tunnel deformation, and effectively improves tunnel differentiated deformation state along the longitudinal direction. However, different-side DHG can provide a better effect for transverse convergence deformation repair under the premise of minimizing tunnel overall displacement.

An Assessment of Some Mechanical Properties of Harvested Potato Tubers cv. Spunta

Mechanical properties of vegetables or crop materials play a noteworthy part in designing new related implements. These properties can be extracted from force–deformation curves. Several factors, such as soil preparation, irrigation, and pre- and post-harvest treatments influence them. The core objective of this investigation work was to analyze force–deformation curves obtained from compression, penetration, and shear tests of potatoes (Spunta cv.) produced with three tillage implements. The potatoes cv. Spunta were cultivated in loamy sand soil under the center-pivot irrigation system. The tillage implements used were a disc harrow plow, chisel plow, and moldboard plow. The trials were performed at a constant planting depth (15 cm) below the soil and a single plowing speed of 5.4 km/h. All data were expressed as an average of five replicates ± standard deviation. The force–deformation curves analysis showed that the modulus of elasticity for potatoes cv. Spunta ranged from 4.32 to 5.8 N/mm, the bioyield force ranged from 84.25 to 114.12 N, and rupture forces ranged from 100.90 to 139.78 N. Furthermore, the results showed that the average values of the elastic and plastic ranges were 3.0 and 2.1 mm, respectively. The mean value of hardness was 1671.53 N·mm. No significant differences were observed with respect to the two planting seasons, but tillage implements had a significant impact on the characteristics extracted from the compression tests. The mean of the maximum forces required to penetrate the potato during the penetration stage were 41.24 N, 44.86 N, and 47.16 N for potatoes produced with the disc harrow plow, chisel plow, and moldboard plow, respectively. Similarly, the means of the maximum forces required to cut the potato in the shear stage were 724.38 N, 761 N, and 773.43 N for the disc harrow plow, chisel plow, and moldboard plow, respectively. The force–deformation curves showed that additional information might be required to obtain a complete description of the potato quality necessary to harvest potatoes cv. Spunta using harvesting and handling equipment with reduced economic loss. An extensive study of the soil characteristics and the above-mentioned properties is also recommended. The results obtained about the mechanical characteristics of potatoes cv. Spunta can be useful in providing information that aids in designing potato harvesting machines and in potato products factories.

Numerical method for the form finding and force analysis of non-prestressed cable-membrane structures with mechanism displacement

The non-prestressed cable-membrane structures exhibit significant nonlinear characteristics such as mechanism displacement and large deformation under external loads. Analyzing such structural behaviors using traditional finite element analysis methods is challenging due to the singularity of the stiffness matrix and the non-convergence of the iterations. In this study, a numerical method based on the vector form intrinsic finite element (VFIFE) method for form finding and force analysis of non-prestressed cable-membrane structures with mechanism displacement is introduced. First, the basic principle and calculation process for analyzing the deformation and internal force of cable-membrane structures are introduced. Second, the applicability of the present method is demonstrated by four numerical examples, including static analysis of the double parabolic inflated membrane and the hemispherical inflated cable-membrane, mechanism motion simulation of the cloth, and large deformation calculation for the flexible curtain. Finally, a spatial non-prestressed cable-membrane model experiment is performed. The effectiveness of VFIFE method is further validated by comparing the measured displacement and internal force to the numerical results. It is shown that the numerical method proposed in this study can effectively simulate the morphological evolution and internal force distribution for the flexible cable-membrane structures with large mechanism displacement, providing a reference for analyzing such practical engineering problems involving strongly nonlinear characteristics.

Tunable deformation behavior of 4D printed shape memory polymers with embedded pre-stretched elastomers

Four-dimensional (4D) printing has attracted considerable attention for its diverse capabilities. However, there has been limited discussion regarding the direct programming of a 3D shape during the 4D printing process to enable active deformation under external stimuli. Therefore, we have developed a novel 4D printing method that imparts active deformation capabilities to shape memory polymers (SMPs) by embedding pre-stretched elastomers using UV-curing bonding. Comprehensive studies have been conducted on elastomer modifications, the bonding performance between pre-stretched elastomers with SMPs, as well as the thermally and electrically responsive deformation behaviors of active deformation SMPs samples. The bending curvature of thermally responsive active deformation SMPs samples exhibited a clear linear relationship with the stretch ratio and the offset position of the pre-stretched elastomers. By adjusting the inclination angle and embedding position of pre-stretched elastomers, the SMPs samples successfully achieved various forms of active deformation, including torsional, segmented, and wave-shaped deformations. Moreover, the integration of an embedded silver nanowire (AgNW) electrothermal layer (ETL) in SMPs samples facilitated electrically responsive deformations. The deformation speed and force of SMPs samples can be regulated by controlling the applied current. Thermally responsive flowers, electrically responsive cross-shaped grippers, as well as reverse deformation grippers were designed and printed. These application examples effectively exemplified the immense potential of active deformation SMPs in the fields of soft robotics, flexible electronic devices, and aerospace equipment.

Correlation Analysis of Tunnel Deformation and Internal Force in the Earthquake Based on Tunnel Inclination

An increasing number of studies have shown that the seismic response of shield tunnels differs from that of aboveground structures. While the seismic response of aboveground structures is mainly influenced by the peak acceleration and frequency of the earthquake, the seismic response of shield tunnels is more influenced by the ground displacement due to the surrounding soil layers. In this study, it is not appropriate to follow the seismic concept of aboveground structures. Dynamic time-history analysis is a powerful and effective method to study the seismic response of tunnels in the typical subway in this paper. The analysis results show that the overall levelling of the tunnel will not affect the tunnel too much, and the seismic response of the tunnel is mainly related to the relative displacement of the ground around the tunnel. The analysis results show that the internal force of the tunnel and the tunnel inclination have a good linear relationship, and the tunnel inclination can be used to measure the magnitude of the seismic response of the tunnel. In the seismic design of shield tunnels, the inclination of the tunnel can be taken into account to evaluate the change in the internal forces of the tunnel during earthquakes, which avoids the need for complex dynamic time-history analysis and greatly improves the efficiency of the seismic design of shield tunnels.

Toe Box Shape of Running Shoes Affects In-Shoe Foot Displacement and Deformation: A Randomized Crossover Study.

Long-distance running is popular but associated with a high risk of injuries, particularly toe-related injuries. Limited research has focused on preventive measures, prompting exploration into the efficacy of raised toe box running shoes. This study aimed to investigate the effect of running shoes with raised toe boxes on preventing toe injuries caused by distance running. A randomized crossover design involved 25 male marathon runners (height: 1.70 ± 0.02 m, weight: 62.6 + 4.5 kg) wearing both raised toe box (extended by 8 mm along the vertical axis and 3 mm along the sagittal axis) and regular toe box running shoes. Ground reaction force (GRF), in-shoe displacement, and degree of toe deformation (based on the distance change between the toe and the metatarsal head) were collected. Wearing raised toe box shoes resulted in a significant reduction in vertical (p = 0.001) and antero-posterior (p = 0.015) ground reaction forces during the loading phase, with a notable increase in vertical ground reaction force during the toe-off phase (p < 0.001). In-shoe displacement showed significant decreased movement in the forefoot medial (p < 0.001) and rearfoot (medial: p < 0.001, lateral: p < 0.001) and significant increased displacement in the midfoot (medial: p = 0.002, lateral: p < 0.001). Impact severity on the hallux significantly decreased (p < 0.001), while impact on the small toes showed no significant reduction (p = 0.067). Raised toe box running shoes offer an effective means of reducing toe injuries caused by long-distance running.

Experimental and theoretical investigation on the impact dynamic response of CFDST-K joints under different structure-related parameters

K-joints have been commonly used in steel structures benefiting from excellent connection performance. In this study, a combined experimental and nonlinear analysis was performed on CFDST-K joints to investigate the displacement, strain evolution, bearing capacity degradation, impact force, and energy absorption capacity in detail with different structure-related parameters such as hollow rate and steel tube thickness. The finite element model was developed and validated by experimental results. Results indicated that the CFDST-K joint can effectively enhance impact resistance with a more reasonable energy distribution. To improve the anti-impact property, the optimal hollow rate is 0.63 and the diameter-to-thickness ratio of the outer tube should be less than 30. Meanwhile, the inner tube thickness had little effect on impact resistance under low-impact energy. Finally, simplified calculation methods for the deformation and impact force were derived based on a parametric study on the dynamic response by discussing the influence of the impact energy, hollow rate, diameter-to-thickness ratio, and axial compression ratio. The findings can serve as a foundation for the development of more reliable CFDST-K joints for steel structures.

Strain rate and temperature rate behavior of ultra-high-strength 1770 steel: Base for transverse impact analysis

The investigation was motivated by the widespread use of ultra-high-strength steels in cable-stayed bridges and armor steel plates. These structures are exposed to elevated risks from extreme loads, including vehicle impacts and blast loadings. The study aimed to investigate the mechanical properties of 1770 steel for applications in extreme conditions. The strain rates and temperatures ranged from 0.00095 s−1 to 1303 s−1 and 20 °C–900 °C, respectively. Tensile tests were conducted at various strain rates using a Split Hopkinson Tension Bar for dynamic testing and a universal testing machine for quasi-static testing at room temperature (20 °C). Quasi-static tension at elevated temperatures was carried out using an electromechanical testing machine coupled with a heating device. A uniform temperature distribution inside the specimens was ensured by a 30-min holding time. The results of the tensile test indicate that the 1770 steel displays notable thermal softening effects and strain rate hardening that differ from mild steel. The standard Johnson-Cook (J-C) model was found to be inadequate in accurately predicting the strain rate effects of this specimen. To address this issue, the strain rate parameter C in the standard model was adjusted to create the modified J-C model, which demonstrated good agreement with the experimental results. To further demonstrate the modified model and the identified parameters, drop hammer impact tests and corresponding numerical simulations were conducted. The impact test and numerical simulation results showed good agreement in terms of deformation and contact force. The mechanical properties and the constitutive models can serve as a design reference for the ultra-high-strength 1770 steel in extreme envirnments, as well as a theoretical basis for fitting material models of similar ultra-high-strength steels.

Longitudinal structural behavior of shield tunnel with large diameter and small curvature

The structural mechanism of a large-diameter curved tunnel is introduced in detail because no relevant calculation method is available. A longitudinal discontinuous contact model is established based on the newly built North Highway Tunnel in Shanghai, China. First, the load-spreading mechanism of circumferential joints was considered. Second, the distribution laws of the longitudinal internal force, settlement, and joint deformation of curved and straight tunnels under the same load were analyzed and compared. Finally, a model test is conducted to verify the effectiveness of the discontinuous contact model. The results indicated that with an increase in the radius of curvature, the maximum internal force and deformation decreased. The internal forces and deformations of straight and curved tunnels are quite different; therefore, the design method for a straight tunnel cannot be used in the design of curved tunnels. The overall and local deformations of the curved tunnel were affected by end displacement.

Calculation model of bending deformation force of magnesium alloy integral panel

The mechanical characteristics of bending forming for magnesium alloy panel is analyzed, and mechanical model is established, stress and strain state is analyzed. A calculation model of the bending force of magnesium alloy panels is proposed firstly, which considers panel thickness, die width, and bending deformation coefficient of the panel. The theoretical calculation results of bending force for magnesium alloy panels are consistent with experimental results, in which the maximum relative error is 4.96%. The bending force is related to the curvature radius and forming temperature of the panel. As the reduction height increases, the curvature radius of the panel decreases, and the bending force increases. As the deformation temperature increases, the bending force decreases.

Experimental Study on Compression Failure of Type II Ballastless Track Slab Based on Optical Fiber Sensing

Ballastless track structures are widely employed in high-speed rail networks because of their superior safety and durability. Among the various types of ballastless track, the Type II slab is currently one of the most extensively used and mature technologies in practice. Over the course of its service life, the damage within the ballastless track structure gradually accumulates in response to increased external loads. Therefore, it is crucial to continuously monitor the health condition of the track structure. In this study, a quasi-distributed fiber optic sensing system is adopted to monitor the deformation capacity and force performance of a Type II ballastless track slab under vertical load. The investigation aims to analyze the damage mechanism of the track structure under vertical pressure by assessing the deformation differences among its different components. The findings reveal that the incorporation of vertical reinforcement can enhance the pressure bearing capacity of the cement asphalt mortar layer to a certain extent, subsequently affecting the stress dilation. The stress performance of the ballastless track slab can be effectively monitored using the quasi-distributed fiber optic sensing technology under pressure. The outcomes of this research offer valuable insights for controlling displacement and analyzing damage in ballastless railway systems subjected to compression.

Contact stiffness of the multi-indenter contact interface

Mechanical contact plays a pivotal role in both industrial and daily life applications. Contact stiffness of a multi-indenter contact interface fundamentally determines force–deformation relations. However, the understanding of the overall contact stiffness from the historical perspective is limited owing to inherent difficulties in precisely characterizing the interaction in multi-indenter contacts. In this study, the mechanical strong interaction among indenters is pinpointed. A theoretical model for accurately determining the contact stiffness of multi-indenter contact interface is developed. The physical mechanism of the contact stiffness of multi-indenter contact interface is revealed. The theoretical model is solidly validated by experiment and simulation. More importantly, the present theoretical model can predict the contact stiffness of contact interfaces with complex and irregular configurations, which may be filled up with indenters of hierarchical structures. The critical load is determined to guarantee the finished product rate during transfer printing. This is experimentally evidenced by the transfer printing of silicon wafers with complexly customized patterns. The present study provides a profound guidance for various engineering applications such as fabrication and integration of micro- and nano-electronic chips as well as electronic devices.

Sweet Cherry Fruit Firmness Evaluation Using Compression Distance Methods

Flesh firmness in sweet cherries is determined using the measurement of normalized deformation force, i.e., determining the required force for a distance equal to 5 or 10% of the diameter of the cherries per millimeter. However, a firmness method involving a defined distance is quite simple and suitable for easy applications. Hence, our study focuses on the impact of fruit physiology under various and fixed distances. To assess the firmness evaluation, two sweet cherry cultivars (Canada Giant and Regina) were selected and subjected to three different levels of compression distance equal to 1%, 5%, 10% of the fruit’s small thickness dimension along with a consistent compression distance of 0.16 mm. There was a strong correlation between panelists’ preferences and the fruit that had been subjected to both a 1% deformation force and a fixed distance of 0.16 mm within each cultivar. Physiological traits, membrane integrity, and the metabolome of the fruit in these categories were mostly unaffected by the control (0%), or 1%, deformation force, as shown by clustering and PCA analysis. The control and 1% deformation force groups showed similar patterns, contrary to those of the 5% and 10% deformation force groups. Given these considerations, a fixed distance of 0.16 mm and a minimal 1% deformation force possess the potential to be employed and implemented for monitoring the firmness of sweet cherries during postharvest preservation.

Effect of cross wall on the strut forces for braced excavations in clays

This study evaluates and estimates the effect of cross walls on the strut force for braced excavation in clays by using three-dimensional finite element analysis. A well-documented case history of a braced excavation with cross walls was utilized to validate the numerical analysis. Furthermore, a series of parametric studies were conducted to evaluate the distribution of strut force by considering different schematics of cross walls. The results revealed that implementing cross walls inside the excavation could significantly reduce the wall deformation and strut force along the wall section, particularly for the location near cross walls. In addition, a new empirical method was proposed to estimate the maximum strut force based on the apparent earth pressure for braced excavation with cross walls, which was verified through case histories. Finally, this study concluded that the existence of cross walls in braced excavations could ensure a safer bracing system and excavation design.

Deformation and retentive forces variations of the additively manufactured cobalt-chromium and titanium alloys dental clasps

This in vitro study aimed to evaluate the additive manufacturing (AM) of cobalt chromium Co-Cr and titanium Ti alloy clasps for clinical use. After scanning the Ni-Cr die of the first molar, Akers' clasps were designed using computer-aided design/ computer-aided manufacturing (CAD/CAM). The clasps were manufactured from Co-Cr-W dental alloy and Ti-6Al-4V alloy powder using AM machines. Then, they were divided into two groups. The initial retentive force of the clasps was measured using a universal testing machine. Cyclic loading of the clasps was carried out by a specially designed insertion-removal testing apparatus in wet condition up to 5000 cycles. Retentive force was measured at 1000, 2000, 3000, 4000, and 5000 cycles. Moreover, the intaglio surface of each clasp was scanned using the scanner; and superimposition between the pre- and post-cycling clasp files was performed to evaluate deformation after cyclic loading. The fitting surfaces of retentive clasp tips were examined with a scanning electron microscope (SEM). Finally, it has been found that the initial retentive force for the Co-Cr group was 10.81 ± 0.37 N, and for the Ti group was 5.41 ± 0.18 N. Additionally, during the testing periods, both Co-Cr and Ti clasps continued to lose retentive force within the cycles of placement and removal. This effect was more prominent in the Co-Cr than in the Ti clasps. The distances between pre- and post-cycling in the retentive arm were −0.290 ± 0.11 mm and −0.004 ± 0.01 mm in Co-Cr and Ti alloys, respectively, and in the reciprocal arm were −0.072 ± 0.04 mm and −0.032 ± 0.04 mm in Co-Cr and Ti alloys, respectively. The retentive force required to remove the Ti clasps was found to be significantly lower than those required to dislodge the Co-Cr clasps. Co-Cr and Ti clasps lost significant amounts of retentive force from the initial use to the 3.5-year periods of simulated clinical use.

Improving the lateral load resistance capacity of cellular lightweight concrete (CLC) block masonry walls through ferrocement overlay

Cellular lightweight concrete (CLC) block masonry is an eco-friendly building material gaining popularity in both developed and developing countries. Despite its increasing use, the material's behavior under seismic loading remains insufficiently understood. This research involved quasi-static testing of two full-scale CLC blocks masonry walls strengthened with ferrocement overlay. One of the strengthened walls was subjected to confinement, while the other was unconfined. The aim was to assess their seismic performance by comparing force deformation curves, damping, stiffness degradation, and structural performance levels with non-strengthened walls. The findings indicate that the strengthened masonry outperformed the unreinforced version, suggesting that CLC block masonry exhibits potential for effective performance in low to moderate seismic zones.

Study of the properties of a composite material Fe78Si9B13 / GNP in an epoxy matrix

This study investigates the properties of a composite material obtained by mixing Fe78Si9B13 metallic powders (at %) with graphene nanoplates (GNP) in an epoxy matrix. Four composite types were created with GNP weight proportions of 0%, 0.5%, 1.0%, and 1.5%. The composites were embedded in transparent epoxy with weight proportions of 10%, 15%, and 20%, and then filled into 7 x 20 mm cylindrical probes. Twelve samples were prepared, and another 12 samples were subjected to a longitudinal magnetic field of 1 kG. All samples were tested with a Universal Testing Machine (Model WDW 10E) up to a maximum force of 20 kN. The experiment recorded deformation (ΔH) vs. charge force. Most samples showed a maximum compression resistance of 390 MPa, except for a few that did not exceed 100 MPa. The magnetically oriented samples showed a greater elastic limit in the range of 200 to 270 MPa. Optical microscopy was used to observe the ordering of the particles after the application of the magnetic field. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction were used to characterize the structure of the composite components. A vibrating sample magnetometer (VSM) was used to characterize the magnetic behavior of the metallic powders in the composite.

Principles of Minimally Invasive Reduction and Nail Fixation for Subtrochanteric Femur Fractures.

Subtrochanteric femur fractures have a reputation as difficult orthopaedic injuries to treat. Strong deforming forces, including the hip musculature and high physiologic forces, must be counteracted to obtain and maintain reduction. Adding to the complexity is a wide variety of fracture morphologies that must be recognized to execute an appropriate surgical plan. The challenging nature of this injury is demonstrated by nonunion rates of 4% to 5%, but some series have reports of up to 15% and malunion rates of 10% to 15%. Improved outcomes have been shown to be dependent on appropriate reduction and stable fixation, which can be achieved with less surgical insult. The treating surgeon must have a thorough understanding of the injury characteristics and reduction techniques to appropriately execute minimally invasive techniques for these difficult fractures.

Stretchable stiffness-tuning of liquid metal elastomer triggered by homocrystal seeds

The hybrid structure of liquid metal units and organic elastomer has huge potential in achieving stretchable and reversible stiffness regulation, while such tuning is often restrained by high energy consumption for liquid metal solidification. Here, we conceive to solve the above challenge through introducing the fully leveraging interaction between supercooled liquid metal and homocrystal seeds within silicone elastomer. It is disclosed that the supercooled liquid metal-elastomer can maintain an extremely stable soft state until the supercooling is eliminated by modulating the mechanical force and elastomer deformation. This circumvents the utilization of intricate refrigeration equipment and offers a highly efficient and concise strategy for stiffness regulation. Moreover, conceptual experiments were performed to demonstrate the practical values of this technology through designing and testing the new shape memory materials, temperature-sensitive switches, and controlled circuits. The solidification mechanisms of supercooled Ga triggered by homocrystal seeds were interpreted. Overall, the present finding has generalized purposes and holds promise to significantly extend the theoretical and technological categories of classical stiffness tunable materials.