Influence Of Fillet Radius Research Articles

Stress Loss of Pre-Tensed CFRP Strips Strengthening Square RС Column

Pre-tensing the CFRP strip strengthening RC column can improve the strain lag of the confined concrete and avoid unloading of column in advance. The pre-stress of strip has an important influence of strengthen. Stress loss of the strip pre-tensed by using the device proposed were investigated by using an experimental test. Firstly, the reasons for the stress loss of strip were analyzed according to the working principle of the device and the strengthening procedure. Then the primary causes of the stress loss, such as friction, relaxation and removing device, were experimentally tested. The influence of the pretension, detail and sectional geometric dimension on the stress loss of the strip were studied. The results show that all three types of pre-stress losses increase significantly with the initial stress. Increasing the cross-sectional size would reduce the relaxation and unwinding losses, but it has little effect on friction losses. The influence of fillet radius on the pre-stress loss was negligible, but in order to avoid premature tearing of local CFRP caused by stress concentration, the chamfer should be made as large as possible within the thickness of concrete protective cover. The test also found that friction was the main cause of stress loss, and friction loss accounts for more than 90% of the total loss.

Analytical Solution of Stiffness for a Corner-Fillet Leaf-Spring Type Flexure Hinge with a Long Fatigue Life

Flexure hinges as the displacement guiding and amplifying mechanism or sensing component are widely used for micro-actuators and sensors. However, the existing flexure hinges, leaf-spring or notch type, cause serious stress concentration which severely weaken the fatigue life of compliance mechanism. Therefore, developing long fatigue life flexure hinges is very important for high working frequency actuators and sensors, such as fast-tool-servo. Corner-fillet leaf-spring type flexure hinge could provide large displacement with lower stress. Stiffness expressions of it with both fixed-fixed and fixed-guided boundary conditions are derived by using Castigliano’s theorem. The main influence factors for stress concentration are investigated and the formulas of stress concentration factor are obtained in terms of ratio of fillet radius to the minimum thickness. These analytical formulas have been verified by comparing with finite element analysis (FEA) results. Stress-life method is chosen to research the influence of fillet radius on fatigue life and the results indicate fillet radius can improve fatigue life of flexure hinge effectively. The proposed analytical solution is the fundamental of optimal design of a leaf-spring type flexure hinge based mechanism with fatigue life constraints.

Influences of fillet radius and draft angle on local loading process of titanium alloy T-shaped components

In order to study influences of geometric parameters on the T-shaped components local loading process, a new mathematical model considering the fillet radius and draft angle was established by using the slab method. The results obtained by the mathematical model agree with the data form experiment and numerical simulation, and the results are closer to the experimental and simulation results. The influence of draft angle may be neglected under the forming conditions used. The influence of fillet radius is notable, especially in the case that the ratio of fillet radius to rib width is less than 0.75.

The Measurement of Actual Strains at Gear Teeth, Influence of Fillet Radius on Stresses and Tooth Strength

With miniature strain gauges having a 0.6 mm gauge length, the strains were measured that occurred at various places in the fillet of spur gears (modulus: m = 10 mm). With this method, gears were tested of varying fillet radii. From the measured results stress concentration factors could be derived that can be used to calculate the actual stresses from the nominal stresses. The measured stresses were compared with the stresses that had been determined photoelastically and analytically according to the method of the finite elements and the integral equation method. As a consequence, it appears to be possible to apply the general strength laws to the gear tooth strength and to superpose the gear tooth stresses upon other stresses (e.g., stresses caused by shrink fitting of a wheel rim).