Percentage Increase In Pressure Research Articles

Elastoplastic analysis in functionally graded thick-walled rotating transversely isotropic cylinder under a radial temperature gradient and uniform pressure

In this research paper, an analytical solution with numerical illustration is presented for elastoplastic analysis in a functionally graded thick-walled rotating transversely isotropic cylinder under a radial temperature gradient and uniform pressure using the transition theory of Seth and generalized strain measure theory. The theory of Seth requires no assumptions, such as infinitesimally small deformation or material incompressibility, or a yield criterion, and is important in determining elastoplastic transitional stresses and fully plastic stresses on the basis of Lebesgue strain measure. The combined impacts of an inhomogeneity parameter, uniform pressure, temperature, and angular speed are discussed numerically and shown graphically. It is concluded that a functionally graded thick-walled rotating cylinder made of steel subjected to a radial temperature gradient and uniform pressure is on safer than a cylinder made of titanium, owing to the percentage increase in pressure. This, in turn, brings to the concept of “stress saving,” which reduces the potential for thick-walled cylinder failure. The fully plastic circumferential stress with the application of thermal effects in a functionally graded cylinder is greater than that at room temperature on the inner surface, whereas fully plastic circumferential and radial stresses for a homogeneous cylinder are independent of thermal effects.

Pressure flow pattern of varicocele veins and its correlation with testicular blood flow and semen parameters.

The pressure pattern in varicocele veins of infertile patients and its correlation with semen quality and testicular blood flow was determined. Consecutive patients at andro-urology clinic of a teaching hospital undergoing microsurgical varicocelectomy were included. Their semen quality and testicular blood flow were determined. Peak systolic velocity (PSV) and resistive index (RI) of subcapsular and intraparenchymal branches of testicular artery were noted by colour Doppler ultrasonography. During surgery before ligation of varicocele veins, intravenous pressures of internal spermatic (ISV) and external spermatic (ESV) veins were determined at baseline and after Valsalva manoeuvre. Thirty patients, 20-45years old, were evaluated. Baseline pressure for maximum dilated ISV (A), less dilated ISV (B) and ESV was 15.93±6.34, 12.38±4.60 and 12.92±5.65mm. Hg, respectively, which increased after Valsalva by 104.4%, 116.2% and 38.22% respectively. Correlation (r=-.71; p<.05) was appreciated between percentage increase in pressure of ISV B with PSV of intraparenchymal testicular arteries and progressive motility (r=-.759; p<.05), nonprogressive motility (r=-.738; p<.05) and morphology (r=-.653; p=.07) of spermatozoa. In conclusion, ISV develops higher pressure on Valsalva as compared to ESV and has correlation with semen quality and testicular blood flow.

Collapse Pressure Analysis in Torsion of a Functionally Graded Thick-walled Circular Cylinder under External Pressure

Abstract A hollow thick-walled cylinder made of functionally graded material subjected to twist has been analyzed. The objective of this paper is to provide the guidance to design the torsion of thick-walled cylinder made of functionally graded material so that collapse of cylinder due to external pressure can be avoided. The concept of transition theory based on the concept of Lebesgue strain measure has been used to simplify the constitutive equations. Results have been analyzed theoretically and discussed numerically. From the discussion, we can conclude that highly non-homogeneous cylinder is on the safer side of the design as compared to lesser non-homogeneous cylinder. This is because of the reason that percentage increase in pressure required for initial yielding to become fully plastic is very high for non-homogeneous cylinder whose non-homogeneity increases radially as compared to lesser non-homogeneous cylinder. Also, non-homogeneous cylinder whose thickness is very high is on the safer side of the design as compared to less thick-walled cylinders because percentage increase in pressure required for initial yielding to become fully plastic is very high for highly thick-walled cylinders as compared to other cases.

English

Elastic-plastic stresses for a transversely isotropic thick-walled rotating cylinder under internal pressure have been obtained by using Seth’s transition theory. It has been observed that a thick-walled circular cylinder made of isotropic material yields at the internal surface at a high pressure as compared to cylinder made of transversely isotropic material. With the increase in angular speed, much less pressure is required for initial yielding at the internal surface for transversely isotropic material as compared to isotropic material. For fullyplastic state, circumferential stress is maximum at the external surface. Thick-walled circular cylinder made of transversely isotropic material requires high percentage increase in pressure to become fully plastic as compared to isotropic cylinder. Therefore, circular cylinder made of transversely isotropic material is on the safer side of the design as compared to cylinder made of isotropic material. Defence Science Journal, 2009, 59(3), pp.260-264 , DOI:http://dx.doi.org/10.14429/dsj.59.1519

Elastic-plastic transition stresses in a transversely isotropic thick-walled cylinder subjected to internal pressure and steady-state temperature

Elastic-plastic transitional stresses in a transversely isotropic thick-walled cylinder subjected to internal pressure and steady-state temperature have been derived by using Seth's transition theory. The combined effects of pressure and temperature has been presented graphically and discussed. It has been observed that at room temperature, thick-walled cylinder made of isotropic material yields at a high pressure at the internal surface as compared to cylinder made of transversely isotropic material. With the introduction of thermal effects isotropic/transversely isotropic cylinder yields at a lower pressure whereas cylinder made of isotropic material requires less percentage increase in pressure to become fully-plastic from its initial yielding as compared to cylinder made of transversely isotropic material.

Compression Therapy: Effects of Posture and Application Techniques on Initial Pressures Delivered by Bandages of Different Physical Properties

Objective To define the pressures and gradients achieved by different bandages when applied by alternative bandaging techniques. Methods An experienced bandager applied six bandages to the same leg of a volunteer using three application techniques. Pressure measurements were taken at the ankle, gaiter, calf and upper calf in three postures. Results All bandages gave consistent pressures with all standard deviations falling below 7 mmHg. The percentage increase in pressure from resting leg to standing was inversely related to bandage elasticity. Pressures were similar at the upper calf among the bandages for each application technique in each posture (differences <10 mmHg). Small differences in pressure among the bandages (4–15 mmHg) occurred at the ankle for the resting leg with a reduction in pressure between 6 and 63% at the upper calf compared to the ankle. These differences in ankle pressure were more marked on sitting (differences 15–18 mmHg) and standing (differences 15–27 mmHg), which resulted in substantial differences in gradients. Conclusions Striking variations in pressures and gradients were observed between bandages of different physical properties applied using alternative application techniques. In order to achieve clinical benefits without tissue damage, it is essential that the therapist appreciates how a bandage will react with a specific application technique.

Elastic-plastic Transition of a Non-homogeneous Thick-walled Circular Cylinder under Internal Pressure

Elastic-plastic stresses have been derived for a cylinder under internal pressure using Seth's transition theory. The effect of non-homogeneity has been discu ssed numerically and depicted graphically. It has been observed that a cylinder made of non-homogeneous material with nohomogeneity increasing radially requires a higher percentage increase in pressure to become fully plastic than to its initial yielding as compared to a homogeneous cylinder and is on the safer side of the design.