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Design and Finite Element Analysis of Vertical Pressure Vessels Subjected To Applied Forces

Design and Finite Element Analysis of Vertical Pressure Vessels Subjected To Applied Forces

Steel, by about 2.08% for Austenitic Stainless Steel and by about 1.1% for Alloy Steel when compared with by applying internal pressures.By observing modal analysis results, the frequencies are slightly increasing when internal + external pressures are applied than applying internal

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On a recursive formulation for solving inverse form finding problems in isotropic elastoplasticity

On a recursive formulation for solving inverse form finding problems in isotropic elastoplasticity

In this section, the previously presented method for solving inverse form finding problems in isotropic elastoplasticity is evaluated by three numerical examples. Since elastoplas- ticity is a path-dependent problem, the applied forces in the direct computation are decomposed in several load steps. After each load step the heterogeneous set of internal variables obtained at the equilibrium is used for the initialisation of the Newton–Raphson method in order to reach the equilibrium at the next load step. The inverse computation is performed with only one load step because the plastic strains are given and frozen, so that the problem remains elastic (Equation 10). The obtained final undeformed config- urations are plotted. The undeformed configurations are subsequently taken as an input for the direct mechanical formulation. The evolution of the obtained deformed configu- ration after the last iteration, on which the equivalent plastic strain is plotted, is shown. The equivalent plastic strain is obtained according to:
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Mechanical Behavior of Materials Course Notes, 2 nd Edition

Mechanical Behavior of Materials Course Notes, 2 nd Edition

These course notes deal with the mechanical response of materials to applied forces or loads. Mechanical properties are amongst the most structure sensitive properties. As such, it is critical that engineering students understand the role of microstructure in determining the final properties of materials.

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In this cha chapter pter 8A Force diagrams and the triangle of forces 8B Newton’s First Law of Motion 8C Momentum 8D Relative velocity 8E Using vectors in geometry

In this cha chapter pter 8A Force diagrams and the triangle of forces 8B Newton’s First Law of Motion 8C Momentum 8D Relative velocity 8E Using vectors in geometry

Applied forces are the pushes or pulls exerted on objects due to con- tact. They are forces with which we have daily experience. The normal contact force acting upwards on a book resting on a table or on us as we stand on the floor or sit on a chair are examples of applied forces. Other examples of applied forces include tensile forces in taut strings and cables (as in the cable used by a crane or rescue helicopter), and compressed forces acting on weight-bearing rods.

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Bulk elastic properties of chicken embryos during somitogenesis

Bulk elastic properties of chicken embryos during somitogenesis

Since studies of the biomechanics of development must begin with quantitative mea- surements of embryonic-tissue mechanical properties, numerous researchers have stud- ied tissue mechanics in specific cases. Forgacs and others [21] have used compression apparatus to measure the viscoelastic behavior of spherical cell aggregates reconstituted from embryonic tissues extracted from limb bud, liver, heart and retina. Moore and coworkers, also using a compression method, have measured how the elastic modulus changes in time for explants of the involuting marginal zone from Xenopus laevis [22]. Recently Wiebe and Brodland, using cantilever-applied forces, elongated tissues and measured the stress of extracted parts of embryonic epithelia from Axolotl [23]. Zamir and Tabler have applied a microindentation method to measure the elastic properties and residual stress in early embryonic chick heart [24]. Murayama and colleagues have also used indentation of the area pellucida of bovine ovum to measure its Young's modu- lus [25].
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Musculoskeletal modelling of muscle activation and applied external forces for the correction of scoliosis

Musculoskeletal modelling of muscle activation and applied external forces for the correction of scoliosis

was assumed to be negligible as the focus was the applica- tion of instantaneous corrective force to the model while in the prone position. The mechanical properties of the model were identical on the left and right sides in the nor- mal upright position. It has been demonstrated by that side dominance affects muscle properties with regards to activation levels and fatigability [32]. This would also need to be considered in practice. The same objective function was utilised in all models to allow comparison across the conditions simulated. The sum of the squares of the verte- bral distances was chosen, as it had been used in previous studies. Different objective functions such as combina- tions of individual vertebral rotations or curve areas could have also been used, and it is possible that tailoring different objective functions to each model would improve individual results. Kyphosis and lordosis, conditions often associated with scoliosis [6] were not examined in this study, as the main focus was the varying Cobb angle for the scoliotic curve. They could be accounted for by adjusting the objective function accordingly. Externally applied forces were not intended to represent any specific treatment directly but could be adjusted to be representa- tive of brace forces or other therapeutic treatments involv- ing external forces applied to the torso. Similarly, muscle activations elicited by the optimization were not necessar- ily representative of either electrical stimulation or phys- ical therapy, and further adjustment would be necessary to represent a more realistic in vivo treatment. The results of this study show the instantaneous correction achieved by the optimizer. This provides an insight into which muscles should be activated to correct specific curves to achieve the best initial result but does not necessarily reflect the results that would be achieved in a long term in vivo treatment. The long-term sustainability of such treatments in vivo is therefore beyond the scope of this modelling study.
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Shell clamping behaviour in the limpet Cellana tramoserica

Shell clamping behaviour in the limpet Cellana tramoserica

It is widely acknowledged that limpets ‘clamp’ or ‘hunker down’ when disturbed in an effort to prevent dislodgement (Cook et al., 1969; McAlister and Fisher, 1968). Until now, however, there has been no attempt to quantify the clamping response or to investigate its role in the limpet adherence mechanism. This lack of information regarding clamping has meant that models of limpet adhesion/shell shape have been unable to include clamping and, hence, treat limpets as mechanical structures rather than biological organisms that may be able to respond to applied forces (Denny, 2000). This arguably limits the accuracy of these models, particularly their ability to provide insight into the selection of limpet structural characteristics and the metabolic costs of adhesion (Santini et al., 1995).
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An Insight into the Ubiquity of Root Resorption in Orthodontics- A Review

An Insight into the Ubiquity of Root Resorption in Orthodontics- A Review

occurrence of root resorption. When heavy orthodontic forces are applied, a hyaline zone is formed around the tooth root because of the resulting imbalance between the process of bone resorption and deposition and thus, tooth movement stops. This hyaline zone is removed by mononucleus cells and multi-nuclei giant cells along with regeneration of periodontal ligament and the tooth starts to move again. While removal of the hyaline zone, an outer tooth root surface consisting of layer of cementoblasts may be damaged which leads to the loss of protective characteristics of cementum contributing to cementoclasts/osteoclasts resorbing the areas of root and thus exposing the underlying dense mineralized cementum. [10-12] Hence, it is possible that a force occurring during orthodontic treatment may damage outer root surface. The tooth root surface under the hyaline zone resorbs after a few days, when the repair process is already occurring in the periphery. In the literature data, it is stated that the resorption process is completed just after removal of the hyaline zone and when the orthodontic force decreases. [10, 13]
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Analytical solutions for tunnels of elliptical cross section in rheological rock accounting for sequential excavation

Analytical solutions for tunnels of elliptical cross section in rheological rock accounting for sequential excavation

Boundary tractions surface forces applied on the tunnel face to calculate the excavation induced displacements and stresses Number of adopted points in determination of coefficients of i[r]

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Ground forces applied by galloping dogs

Ground forces applied by galloping dogs

are 25% greater in the trailing forelimb of horses, whereas at higher galloping speeds (12·m·s –1 ) peak vertical forces are predicted to be only 19% greater for the trailing forelimb based on the maximum metacarpophalangeal joint angles (Merkens et al., 1993; McGuigan and Wilson, 2003). Horses galloping at high speed also have a longer stance period on the lead forelimb (Deuel and Lawrence, 1986). During slow cantering, horses apply four times greater peak accelerating forces with their trailing forelimbs than with their leading forelimbs (Merkens et al., 1993), which is also much greater than the 12% difference observed in dogs. Differences between dogs galloping at high speed and cantering horses could be due to interspecific differences in body morphology, or they could represent inherent differences between the two gaits. The canter is used by horses at moderate speeds and differs from the high-speed gallop in that the contact phases of the lead forelimb and trailing hindlimb overlap entirely (Merkens et al., 1993; Hildebrand, 1977). Even at high speeds, the transverse gallop of horses differs from the rotary gallop of dogs in that right and left hindlimb ground contacts occur in the same order as forelimb contact. Further, horses galloping at high speeds do not exhibit a flight phase between the stance phases of the lead hindlimb and trailing forelimb. Unfortunately, the ground forces for the transverse gallop of horses or for other animals galloping at high speeds have not been reported.
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Cliff edge seismic evaluation of stack structure using fragility analysis

Cliff edge seismic evaluation of stack structure using fragility analysis

Table 5-7 of FEMA 356 is used instead Table 9-7 of ASCI 41-13 because the specification for circular hollow tubes in the FEMA document can be directly applied for the above mentioned analogy to the stack section. FEMA 356 Table 5-7 differentiate the circular hollow tubes only based on the dimeter to thickness ratio that is compared with a parameter derived from the yielding strength. ASCI 41-13 Table 9- 7 use more complex equations to differentiate between slender and stocky pipe elements which include the stiffness K of the member and the length L. However, since the structural system of the stack is fundamentally different from that of a brace, using more complex equations to differentiate between slender and stocky element will not will not lead to any benefits. In addition, the selected values from FEMA 356 Table 5-7 are more conservative, which in this case is more suitable due to the unclear real failure behaviour. For consistency, the deformation capacities of the axial hinges described above are also based on FEMA 356 Table 5-7.
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UNDERSTANDING, PROSPECTS AND COSTRAINTS OF EMERGING NANOTECHNOLOGY

UNDERSTANDING, PROSPECTS AND COSTRAINTS OF EMERGING NANOTECHNOLOGY

In force measurement ,AFM,s can be used to measure the forces between the probe and the sample as a function. of their mutual separation ,This can be applied to perform force [r]

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A novel self-aligning mechanism to decouple force and torques for a planar exoskeleton joint

A novel self-aligning mechanism to decouple force and torques for a planar exoskeleton joint

Exoskeletons have been proposed to augment strength (Makinson, 1971; Zoss et al., 2006), enhance endurance (Lockheed Martin, 2012; Raytheon, 2012), and restore lost abilities (Berkeley Bionics, 2012; Jezernik et al., 2003; Stienen et al., 2007). These applications span military, (Zoss et al., 2006; Lockheed Martin, 2012; Raytheon, 2012), in- dustrial (Makinson, 1971), and medical (Argo, 2012; Berke- ley Bionics, 2012; Jezernik et al., 2003; Stienen et al., 2007) fields – each with their own challenges; but there exists a common subset of design challenges inherent to all exoskele- ton systems. One of these challenges is how to fit the ex- oskeleton system to the operator. This problem of fit is of par- ticular difficulty for anthropomorphic exoskeletons (Schiele and van der Helm, 2006; Stienen et al., 2009), as they are typically attached to each limb segment of the user. A mis- alignment between a joint in a rigid exoskeleton and the cor- responding biomechanical joint in the human operator pro- duces unexpected and potentially dangerous internal joint forces on the human as well as potential forces on the human- robot physical interface (Schiele and van der Helm, 2006) that couple the operator to the mechanism. Furthermore it has been shown that the attachment pressure has a large ef-
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Dynamic Behavior Characterization of the Milling Tool During the Cutting Process

Dynamic Behavior Characterization of the Milling Tool During the Cutting Process

imperfections or the defects of functioning in order to improve the stiffness, the damping or manufacturing precision, [3], [4], [5], [6]. The methods used in monitoring techniques may be classified into two groups, direct and indirect methods. The direct methods are to measure the sizes of tool wear surface such as using optical sensors. The indirect methods are to measure the characteristics closely related with the state of tool wear, such as the cutting power and acoustic emission, [7], [8], [9]. However, due to the complexity of the machining process and the uncertainty in the correlation between the process parameters and tool wear, it is hard to obtain a satisfactory solution in tool wear monitoring, [10]. A large variety of sensors are used for measuring vibrations; piezoelectric transduction is the most common type in vibration sensing in machining operation [3]. Current dynamic milling models deal with the determination of optimal cutting conditions by vibration analysis and by dynamic forces analysis for one direction, two directions and three directions. This approach is not enough for a real dynamic modeling because the cutting process generates both forces and torques (moments). For instant these moments are not taken into account. The main purpose of this research is to develop a dynamic analysis closer to reality, which can answer in terms of processing requirements in three-dimensional dynamic conditions. A model which by integrating the moments generated by the cutting process, moments expressed in the tooth of tool. This approach will bring the necessary information for transferability from a known material by a new material [11], [12], [13]. So is desired to obtain a complete dynamic model which contains the expression and determination of both forces, and the resulting moments. This research is a part of a larger project of developing a dynamic three- dimensional cutting model by integrating the moments generated by cutting process [14]. Important results were obtained by an advanced analysis of vibration, spectral envelope analysis based on a Hilbert transform [15], to identify mechanical defects and obtaining a better response on the milling process quality [16]. In order to reach this objective, an experimental device designed to obtain dynamic information provided by the dynamic system machine/tool/chip/workpiece and to emphasize both mechanical actions (forces and moments) and vibrations synchronized with speed. This paper takes into account the dynamic evolution of the action of milling tool during cutting process. For the correct determination of the dynamic behavior of the mill cutter during the cutting process was adopted a mill cutter with a single tooth. In this case the impact tooth can be monitored and its evolution on a complete rotation of the tool.
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Relationship between sagittal plane kinematics, foot morphology and vertical forces applied to three regions of the foot

Relationship between sagittal plane kinematics, foot morphology and vertical forces applied to three regions of the foot

The aim of this study was to determine if any correlations exist between intersegmental foot kinematics, foot mor- phology and the distribution of sub-segment foot loading. The inter-subject vertical forces acting under each sub-seg- ment of the foot were found to vary more greatly than those acting on the foot as a whole. This is in agreement with previous literature (Guiotto et al. 2013) and indicative that foot sub-segment loading is highly subject-specific. As such, an effective technique for their determination, either through modelling or direct measurement, is essential for the effective use of multi-segment foot models.
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Rapid acceleration in dogs: ground forces and body posture dynamics

Rapid acceleration in dogs: ground forces and body posture dynamics

Because the ability to accelerate rapidly is crucial to the survival and reproductive fitness of most terrestrial animals, it is important to understand how the biomechanics of rapid acceleration differs from that of steady-state locomotion. Here we compare rapid acceleration with high-speed galloping in dogs to investigate the ways in which body and limb posture and ground forces are altered to produce effective acceleration. Seven dogs were videotaped at 250 Hz as they performed ‘maximum effort’ accelerations, starting in a standing position on a force plate and one and two strides before it. These dogs began accelerations by rapidly flexing their ankles and knees as they dropped into a crouch. The crouched posture was maintained in the first accelerating stride such that the ankle and knee were significantly more flexed than during steady high-speed galloping. The hindlimb was also significantly more retracted over the first stance period than during high-speed galloping. Ground forces differed from steady-state locomotion in that rapidly accelerating dogs supported only 43% of their body weight with the forelimbs, compared with 56–64% in steady-state locomotion. The hindlimbs applied greater peak accelerating forces than the forelimbs, but the forelimbs contributed significantly to the dogs’ acceleration by producing 43% of the total propulsive impulse. Kinematically, rapid acceleration differs from steady-state galloping in that the limbs are more flexed and more retracted, while the back undergoes greater pitching movement. Ground reaction forces also differ significantly from steady-state galloping in that almost no decelerating forces are applied while propulsive force impulses are three to six times greater.
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Online Full Text

Online Full Text

An automated minimally invasive surgical instrument was introduced, the modelling and development issues were discussed, and experimental results were presented and analysed in this paper. The proposed surgery instrument has the capability of minimally invasively measuring normal tip interaction forces e.g. grasping and cutting. The instrument features non-invasive actuation of the tip and also the measurement of interaction forces without using any actuator and sensors at the jaws. The grasping direction in the proposed instrument can also be adjusted during the surgical procedure. The modularity feature of this force feedback- enabled minimally invasive instrument makes it interchangeable between various tool tips of all functionalities (e.g. cutter, grasper, and dissector) without loss of control and force measurement capability necessary to avoid tissue damage and to palpate and diagnose tissue and differentiate its stiffness during surgery. A high precision device for the measurement of young modulus of soft tissues were developed and utilised in this research. Experiments were conducted to evaluate capabilities of the proposed instrument in non-invasively measuring normal grasping forces. The result showed high accuracy and performance and verified the ability of the instrument in measuring normal grasping forces and in distinguishing between tissue samples even with slight differences in stiffness. The sterilizability of the instrument and especially the force sensing sleeve also needs improvements in future works before it can be used in surgery operating room.
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Surface-Controlled Properties of Myosin Studied by Electric Field Modulation

Surface-Controlled Properties of Myosin Studied by Electric Field Modulation

However, the similarity in the motility behavior on NC and TMCS in the absence of an electric field (Figure 3) suggests that any difference in the binding characteristics of the two surfaces is rather small, when external forces are not exerted on the actin filaments. Indeed, this is in agreement with previous findings showing that the adsorption of HMM and blocking protein prior to the actual motility assay result in a protein layer which decreases the difference between the overall rigidity of the NC and TMCS surfaces. 47 The coating of surfaces with NC 10, 12, 49 and the functionalization with TMCS 33, 43 have been used extensively as immobilizing
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Online Full Text

Online Full Text

Stable and unstable cutting experiments have been designed. As the magnitude and direction of the cutting force significantly influence the machining accuracy therefore their precise knowledge is required in precision finishing. There are process requirements concerning to the accuracy and quality that are continuously increasing [4], [10] - [13]. A genetic algorithm approach was applied to the simulation model to determine the parameter values of process that would result the simulated cutting forces in ball-milling.

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Models of pressure compaction and their application for wheat meal

Models of pressure compaction and their application for wheat meal

relate to modelling of metals, ceramic or pharmaceutical powders, or chemical materials (Chevanan et al., 2010; Feng et al., 2007; Haware et al., 2009; Paneli and Filho, 2001; Souriou et al., 2009). Equations have often been presented which set the dependencies between the load used (pressure) and the physical properties of powder, pressure vs. specific volume, and internal stress vs. material deforma- tion. Uniaxial confined compression has been applied to describe the elastic properties of food powders (Molenda and Stasiak, 2002; Molenda et al., 2006). The process was de- scribed using both elastic and plastic models, ie Drucker- Prager, Di Maggio-Sandler, and Cam-Clay. They are dis- cussed in numerous works (Chen et al., 2001; Cocks, 2001; Michrafy et al., 2002; Rolland et al., 2012; Sinka et al., 2003; Wu et al., 2005).
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