Squeeze Force Research Articles

Effect of air film squeeze force and surface force on the vibration characteristics of AFM cantilever

Effect of air film squeeze force and surface force on the vibration characteristics of AFM cantilever

Liquid volume and squeeze force effects on nasal irrigation using Volume of Fluid modelling

For various sinonasal conditions, including chronic rhinosinusitis, saline irrigation is an accepted standard-of-care treatment. This study was aimed at determining the effect of increased irrigation volumes and greater squeeze force on mucosal irrigation. A sinonasal cavity computational model was reconstructed from high-resolution CT scans of a healthy, unoperated 25-year old female. Seven combinations of irrigation volumes (70, 150, 200, and 400 mL) and squeeze forces (ramp time 0.1, 0.5, and 1.0 s) at a fixed head tilt of 0 degrees to the horizontal (Frankfort position) were performed. Velocity, pressure, and wall shear stress, together with mapping of surface coverage and residual volumes at specific locations and time were demonstrated. Higher volume irrigation (400 mL) and greater squeeze force (ramp time 0.1 s) improved irrigation coverage on the ipsilateral and contralateral sinonasal surfaces and increased shear force (approximately 140 Pa). An increase in irrigation volume from 70 to 150 mL approximately doubled sinus surface coverage and from 70 to 200 mL tripled sinus surface coverage. A faster squeeze also contributed to increased sinus surface coverage but its effect was less influential. We infer that the greater irrigation volume and squeeze force improve therapeutic benefit in terms of lavage and distribution of topical medications.

Design and Evaluation of a Parallel Cable-Driven Shoulder Mechanism With Series Springs

Abstract Upper limb paralysis and movement disorders resulting from neurologic injuries can be treated with an upper limb exoskeleton robot that assists with movement retraining. Cable-driven exoskeletons have been widely studied because of their lightness, compact structure, and low cost. However, the problems of shoulder squeeze force and system stability have not been solved. In this article, we present a prototype parallel cable-driven shoulder mechanism with series springs. The theoretical analysis suggests that the stability of the mechanism is improved compared with that of the previous mechanism, and the effects of stiffness, upper limb weight, and mechanism parameters on the shoulder joint extrusion pressure are analyzed by simulation and experimental results. The results show that this mechanism plays an important role in reducing or eliminating the shoulder squeeze pressure and improving the stability of the mechanism. Moreover, the mechanism has good portability and can be combined with other exoskeletons to facilitate various robot-assisted upper limb rehabilitation training.

Effect of hole perpendicularity error and squeeze force on the mechanical behaviors of riveted joints.

In the automatic drilling and riveting process, the perpendicular error of the hole is inevitable, which has a great influence on the assembly quality. In the current research, the shear and pull-out behaviors of riveted joints under different perpendicularity errors and squeeze forces were investigated and compared by the quasi-static tests. The fracture of the failed samples was characterized by a scanning electron microscope and the formation process of fracture was discussed. The failure mechanisms of riveted joints were analyzed in detail to guide engineering applications. The test results demonstrated that the shear load and pull-out load of riveted joints increased slightly with the increase of the tilt angle from 0° to 4°. The perpendicularity error did not affect the shear and pull-out failure modes of the riveted joints. However, the squeeze force had a significant effect on the failure modes of the pull-out samples. Fracture analysis showed that the failure of all shear samples occurred at the rivet shaft. Besides, when the squeeze force increased from 15 kN to 23 kN, the failure modes of the pull-out samples changed from the sheet to the rivet itself.

Study on shear behavior of riveted lap joints of aircraft fuselage with different hole diameters and squeeze forces

Riveting is the most important method to connect metal sheets and is widely used in the joining of aircraft components. In the present research, the effect of different hole diameters and squeeze forces on the shear behavior of riveted lap joints is investigated. The variation of shear load with hole diameter under different squeeze forces was obtained by shear tests. Besides, the fracture mode and microstructure of the rivet shank were characterized by SEM, and the formation process of brittleness and plastic fracture was discussed. A 2D axisymmetric finite element model was established with the help of ABAQUS commercial finite element software and the validity of the finite element models was verified by experiments. To investigate the influence of interference distribution on the mechanical behavior of riveted lap joints, the interference distribution and material flow characteristics during the riveting process were analyzed in detail by the finite element methods. The results showed that all the specimens presented a mixed fracture mode of brittleness and plasticity at rivet shank. The area of the brittle fracture region was much smaller than the plastic fracture region. Also, the shear load was enhanced when the hole diameter increased from 4.82 mm to 5.10 mm. The maximum shear load increased by 17.77% and 17.24% under 15 kN and 23 kN squeeze forces respectively. In addition, compared with the squeeze force, increasing the hole diameter could effectively raise the shear load of the riveted lap joints.

Rheo-morphological investigation of static and dynamic stability of self-consolidating concrete: A biphasic approach

Stability and compressive strength of 30 self-consolidating concrete (SCC) mixtures proportioned with normal and low binder contents were investigated as biphasic suspensions of fine mortars (<1.25 mm) and coarse aggregate (>1.25 mm). Static and dynamic stability of the investigated SCC mixtures were evaluated using the penetrometer and T-Box set-ups, respectively. Moreover, the morphological characteristics of different size subclasses of coarse aggregate were assessed using 3D image processing. The investigated fine mortars were characterized in terms of the visco-elastoplastic properties and compressive strength. A new lattice factor was proposed to evaluate the particles’ lattice effect on stability of SCC. On the other hand, new empirical models were proposed to evaluate the inter-particle squeeze force and drag coefficient of the irregularly-shaped coarse aggregate.According to the established correlations, among the morphological characteristics of coarse aggregate, the mean diameter and 3D surface area of coarse aggregate exhibited the most dominant effect on stability (static and dynamic) and compressive strength of SCC, respectively. From rheological point of view, the yield stress and plastic viscosity of fine mortar were found as the main viscoplastic parameters which significantly control the stability of SCC.

Study on maceral liberation characteristics of ball grinding and rod grinding for low-rank coal

ABSTRACT The liberation characteristics of long flame coal from the Chinese Shenhua were studied by comparison of ball grinding and rod grinding. First, the effects of grinding time on maceral liberation under the different particle size range, including vitrinite content (VC), vitrinite liberation degree (VLD) and vitrinite monomer content (VMC) were researched. Then, the influence of different grinding methods on maceral liberation were compared under same grinding fineness. Test results showed that the vitrinite in rod mill grinding is more concentrated in coarser particles compared with ball mill grinding, which provides favorable conditions for subsequent maceral beneficiation. In addition, in the range of +0.125 mm, all indexes with rod grinding are better than that of ball grinding. Especially, in the range of −0.045 mm, the vitrinite yield obtained by rod mill is always higher than that obtained by ball mill when ash content in each particle size range is almost the same. Analysis results show that the stress area of particles is small for ball grinding to result in random cracks. But rod mill crushes particles by slowly increasing squeeze force greater than stress intensity of particles, the force area of particles is larger to protect particle size decrease to a extent.

Characteristic analysis and squeezing force mathematical model for magnetorheological fluid in squeeze mode

Magnetorheological fluid is a kind of intelligent material with a controllable state. It has three working modes: valve mode, shear, and squeeze. The squeeze mode can produce greater response under the external excitation conditions, with significant application potential and advantages. In this paper, a magnetorheological fluid squeeze performance test device was designed, and the squeeze experiments under different magnetic field strengths and loading speed conditions were implemented, and then the MRF squeeze flow theory model was established, which is the key factor affecting the squeeze force are revealed. The experimental results show that the squeeze force change trend presents three stages, of which the first stage represents the state before yielding; the loading speed has a significant effect on the change of the squeeze force curves, especially around 1 mm/s, the squeeze force curves show different development trends. Through theoretical analysis, it is concluded that loading speed, magnetic field change gradient, and magnetorheological fluid dynamic yield strength are the key factors affecting the squeeze force, which provide basic theoretical support for the evaluation and research application of the extrusion performance of magnetic material.

Short and long lever adductor squeeze strength values in 100 elite youth soccer players: Does age and previous groin pain matter?

ObjectiveTo examine adductor squeeze strength in elite youth soccer players by investigating the relationship of age and previous one-year groin pain on adductor squeeze force outputs, and to provide reference values for youth players. DesignCross-sectional study. ParticipantsElite youth soccer players (n = 100; age 14.5 ± 1.9 years; height 168.0 ± 10.7 cm; mass 60.7 ± 13.0 kg) participated. Main outcome measuresAdductor squeeze tests were captured in short and long lever positions, and groin pain assessed via subjective retrospective questionnaire. Multiple linear regressions were computed to compare the effects of age and previous one-year groin pain on adductor squeeze strength. ResultsRaw adductor squeeze force values (N) had a moderate positive relationship with age (short r = 0.517, p < 0.001; long r = 0.457, p < 0.001), but not when force is normalized to body mass (N/kg; short r = 0.014, p = 0.444; long r = −0.173, p = 0.043). Previous groin pain did not have an effect on short or long lever squeeze strength. Reference values for long lever adductor squeeze strength (3.59 ± 0.77 Nm/kg) are provided. ConclusionAge and previous groin pain do not have an effect on adductor squeeze strength values in elite youth soccer players, so comparing values to the present adolescent cohort can be quickly interpreted without adjustment for age or previous injury.

Design variables influencing the fatigue of Al 2024-T3 in riveted aircraft lap joints: Squeeze force and initial fit tolerance

This study experimentally analyzed the influence of squeeze force and initial fit tolerance on the fatigue property of a riveted aircraft lap joint. All specimens were prepared under load control and tested under six levels of fatigue loads. The results showed that an initially oversized rivet might be detrimental to fatigue-life improvement. Increasing the squeeze force within an allowable range could extend the fatigue life generally. A relative decrease was also observed at a higher range of squeeze force. A higher fatigue load was likely to weaken the effect of the interference fit. The reduced fatigue life at higher squeeze forces could be clearly explained in terms of the fretting characteristics on the faying surface as a result of different squeeze forces and load levels. This study suggests that, to fully extend the fatigue life of riveted lap joints, the influence of working fatigue loads must be considered in the structure design.

The singular hydrodynamic interactions between two spheres in Stokes flow

We study exact solutions for the slow viscous flow of an infinite liquid caused by two rigid spheres approaching each either along or parallel to their line of centers, valid at all separations. This goes beyond the applicable range of existing solutions for singular hydrodynamic interactions (HIs), which, for practical applications, are limited to the near-contact or far field region of the flow. For the normal component of the HI, by the use of a bipolar coordinate system, we derive the stream function for the flow as the Reynolds number (Re) tends to zero and a formula for the singular (squeeze) force between the spheres as an infinite series. We also obtain the asymptotic behavior of the forces as the nondimensional separation between the spheres goes to zero and infinity, rigorously confirming and improving upon the known results relevant to a widely accepted lubrication theory. Additionally, we recover the force on a sphere moving perpendicularly to a plane as a special case. For the tangential component, again by using a bipolar coordinate system, we obtain the corresponding infinite series expression of the (shear) singular force between the spheres. All results hold for retreating spheres, consistent with the reversibility of Stokes flow. We demonstrate substantial differences in numerical simulations of colloidal fluids when using the present theory compared with the existing multipole methods. Furthermore, we show that the present theory preserves positive definiteness of the resistance matrix R in a number of situations in which positivity is destroyed for multipole/perturbative methods.

A Novel Dual-Probe-Based Micrograsping System Allowing Dexterous 3-D Orientation Adjustment

This article proposes a two-finger-based micrograsping system with high compliant borosilicate 3.3 glass probes and the corresponding sensing and control algorithms, which enables the orientation manipulation of microparts in three-dimensional (3-D) space. Compared with the existing research, the novelty of this article relies on three aspects: 1) the end-effector of the microgripper is designed to be with high compliance so that the squeeze force exerted on microparts can be more accurately regulated and the proposed microgripper is capable of manipulating fragile microparts; 2) the micrograsping system is endowed the capability to fully manipulate microparts’ orientation without recurring to auxiliary probes or rotary stages; and 3) the vibration characteristic of the grasping arm is investigated as cantilever beam for gasping stability analysis and squeeze force maintaining. In specific, taking spherical microparts with dimensions in the range from tens to hundreds of micrometers as target, the grasping system configuration, and the contact model between the probe and the microparts are first presented. Afterward, kinematics-based motion control strategy for position adjustment and orientation manipulation of microparts is clarified. Then, squeeze force regulation strategy is proposed, including adhesive force evaluation, vision-based squeeze force estimation, and the micropart releasing method. Finally, the vibration characteristic of the grasping arm is investigated as cantilever beam for gasping stability analysis and the squeeze force maintaining. The reliability and availability of the proposed micrograsping system is validated by well-designed experiments. Note to Practitioners —This article is motivated to develop a micrograsping system which enables dexterous rotating manipulation of microparts. The core of the proposed system is the utility of two fistulous tampered borosilicate 3.3 glass probes, which show high compliance in the microdomain. The manifested compliance enables the stably grasping of spherical objects during dexterous rotating manipulation and the vision-based contact force evaluation and regulation. The proposed system can rotate objects about two independent axes so that the orientation of a micropart can be adjusted to the desired one. This is critically important for many practical applications, such as the assembly of microballon and microneedle and the beamed cell penetration.

Numerical investigation of a non-Newtonian fluid squeezed between two parallel disks

The transient, axisymmetric squeeze flow of the non-Newtonian shear thinning material between finite disks is studied numerically. The fluid between disks is assumed to follow the Carreau-Bird model. Two disks approach each other at a constant velocity while no-slip boundary condition is assumed. The time dependent simulation shows the effect of fluid nonlinearity, flow parameters and geometric aspect ratio on the flow dynamic and evolution of squeeze force. Also, some physical phenomena are shown and are explained at the edge of the disks and out of them. The conservation and momentum equations containing inertia effects are solved using moving mesh scheme and finite volume method. The SIMPLE algorithm is used to solve the pressure-velocity coupling.

VibeRo: Vibrotactile Stiffness Perception Interface for Virtual Reality

Haptic interfaces allow a more realistic experience with Virtual Reality (VR). They are used to manipulate virtual objects. These objects can be rigid and soft. In this letter, we have designed and evaluated a vibrotactile hand-held device (VibeRo) to achieve haptic cues of different soft objects. The proposed method is based on combining the vision-driven displacement produced by the pseudo-haptics effect with the haptic illusion of a limb displacement obtained from force-driven synthesis of vibration of a contact surface. VibeRo features a voice-coil actuator and force-sensitive resistors for generating squeeze forces at fingertips. We present an evaluation of VibeRo's pseudo-haptic and haptic illusion effects to render soft virtual objects. The efficacy of the approach was validated in experiments with human subjects.

Generic selection criteria for safety and patient benefit [IX]: Evaluation of "feeling of use" of sodium hyaluronate eye drops using the Haptic Skill Logger (HapLog®) wearable sensor for evaluating haptic behaviors

We compared the pharmaceutical properties, such as surface tension, drop volume, nozzle inner diameter, and force to push the drug product out of the container (squeeze force), of purified sodium hyaluronate eye drops preparations of one brand-name (Hyalein) and 11 generic drugs used for treatment of keratoconjunctiva epithelial disorders, and examined product selection based on the needs of the patient. The surface tension of Nissin (51.0 dyn/cm) and Nitten (52.3 dyn/cm) was significantly lower than that of Hyalein (62.8 dyn/cm), whereas Nitten PF (69.5 dyn/cm) was significantly higher than Hyalein. The drop volume of Tearbalance (42.4 mg), Nissin (43.7 mg), and Nitten (42.7 mg) was significantly lower than that of Hyalein (50.4 mg). We compared the squeeze force using a wearable touch sensor (Haptic Skill Logger: HapLog®) and digital force gauge (DF). The squeeze force of HapLog® showed values of about 1.7- to 3.5-fold higher than that of DF. Moreover, the squeeze force of Eyecare (34.0 N), Kyorin (35.4 N), and Nitten PF (44.3 N) by HapLog® was significantly higher than that of Hyalein (10.5 N). In contrast, the squeeze force of Kyorin (20.8 N) and Nitten PF (25.0 N) by DF was significantly higher than that of Hyalein (12.2 N). Two questionnaire surveys on the feeling of instillation of eye drops revealed a strong negative correlation between feeling of use and squeeze force.

Measurement of squeeze force in narrow gap by AFM probe equipped with a gap control system

Measurement of squeeze force in narrow gap by AFM probe equipped with a gap control system

Dynamic characteristics of magnetorheological fluid squeeze flow considering wall slip and inertia

Magnetorheological fluid has been investigated intensively nowadays, and magnetorheological fluid shows large force capabilities in squeeze mode with wide application potential such as control valve, engine mounts, and impact dampers. In these applications, magnetorheological fluid is flowing in a dynamic environment due to the transient nature of inputs and system characteristics. Hence, this article undertakes a comprehensive study of magnetorheological fluid squeeze flow dynamics behaviors with wall slip, yield, and inertia. First, the dynamic model with the bi-viscous constitutive of magnetorheological fluid squeeze flow including wall slip and inertial force is presented. Then, the mathematical model is validated, matching magnetorheological fluid squeeze dynamic test results very well. Finally, the dynamics behavior and mechanism of magnetorheological fluid squeeze flow with inertia, yield, and wall slip are explored. Results show that (1) increasing yield stress and decreasing initial gap will increase the magnetorheological fluid vertical force greatly; (2) the wall slip affects the yield surface of magnetorheological fluids in the squeeze zone and affects the squeeze force; (3) the inertial force is increasing tremendously as the increased excitation frequency and yield stress and should be included with high-frequency excitation or yield stress.

Modeling the Amplitude Mode of Piezoelectric Microcantilever AFM in Contrast to the Surface of the Sample in a Liquid Medium

This paper deals with the modeling and simulation of the vibration behavior of piezoelectric microcantilever based on the Timoshenko theory and using multi-scale method in the liquid environment, considering the interaction forces in the liquid medium. The effect of viscosity and density is investigated on first four bending modes. The results of topographic simulation for rectangular roughness in the liquid medium and the amplitude mode indicate a reduction in the latency of the first mode from 1.54 to 0.48 and in the second mode from 0.49 to 0.18 compared to the air environment. According to the results of simulation in different working environments, with the increase in the radius of the probe tip, the squeeze force of the liquid will also increase; this increase in the force reduces the amplitude of the vibration motion and the natural frequency. According to the results of the simulation, solution based on the theory of string of spheres with 0.1% error has less accuracy than on multi-scale method with 0.031% error. Regarding the multi-scale method, the Rankl model with a percentage error of 13.47 and the string of sphere model with a percentage error of 0.10 have had a higher accuracy than the similar model of FEM with 14.64% error; the accuracy of the Hosaka model with a percentage error of 18.62 is less than the Rankl model; therefore, the Rankl model has the least error for multi-scale method solving in Timoshenko beam theory.

Experimental and numerical studies of stress/strain characteristics in riveted aircraft lap joints

The fatigue property of riveted lap joint is greatly related to the riveting-induced residual stress, especially the stress distribution on the faying surface. However, an accurate study of the residual stress characteristics in the riveted sheet could be very difficult. In this paper, both numerical and experimental investigations were carried out on the stress/strain characteristics in riveted aircraft lap joints. A special specimen was designed for the test of strain variations on the faying surface of the sheet by microstrain gages. For the numerical simulation, the rivet squeezing process was analyzed using the explicit dynamic finite element (FE) method, whilst a general static FE analysis was employed for the elastic springback after the squeeze force was removed. A comparison of the strain variations between the experimental results and FE simulations shows a general good agreement, although there may be some difference for points measured near the hole surface. The FE analysis reveals that both compressive and tensile residual stresses could be introduced in the riveted sheet. Massive compressive residual stress can be created in the near-surface layer of the hole. However, the stress level is not always increased with increasing the squeeze force, and so is the improvement of fatigue life observed. Further study is still necessary to account for the fatigue life decreasing effect caused by a high squeeze force.

Measurement Properties of an Adductor Strength-Assessment System in Professional Australian Footballers.

To examine the measurement properties of an adductor strength-assessment system in professional Australian footballers. Observational, longitudinal design. Test-retest reliability data were collected from 18 professional Australian footballers from 1 club on the same day during the 2017 Australian Football League season. Week-to-week variation data were collected on 45 professional Australian footballers from 1 club during the same season at 48, 72, and 120 h postmatch (rounds 1-23). Players lay beneath a GroinBar hip-strength testing system in supine position with their knee joints at an angle of 60°. Force (in newtons) was extracted for the left and right limbs of each player and a pain score from 0 to 10 (0 = no pain, 10 = maximum pain) was provided. Coefficient of variation (CV) and smallest worthwhile change were calculated on test-retest data. Signal-to-noise ratio was calculated for each major time point. Mean difference between force scores in a subgroup of players with and without groin pain (n = 18) was collected as evidence of construct validity for the system. Test CV was 6.3% (4.9-9.0%). CV exceeded the smallest worthwhile change on both limbs. Intraclass correlation coefficient was .94. Signal-to-noise ratio ranged from 1.6 to 2.6 on average for 48, 72, and 120 h postmatch. Groin pain had a very likely moderate negative effect on adductor strength (effect size: 0.41). The system possesses greater measurement precision than dynamometry and sphygmomanometer adductor strength-assessment methods in professional Australian footballers. Increased groin pain reduced groin squeeze force production. Practitioners may interpret changes exceeding 6.3% in adductor strength as real.