Search Results for « Internal Bar Strength »

Fatigue failure is the most common failure mode of boring bar in the deep-hole boring processing system. For solving the problem of fatigue failure on boring bar, the new fatigue strength criterion of boring bar is proposed considering the working state including internal and external cutting fluid vortex, linear crack of the across-section, and the maximum bending - torsion coupled stress of boring bar. Firstly, approximate calculation formula of the maximum bending stress was derived considering internal and external cutting fluid coupled effect induced vortex motion. Secondly, near the region of crack tip, the maximum shearing stress was studied when the failure modes of boring bar was considered to linear crack on its cross-section. Finally, the new fatigue strength criterion was established based on bending-torsion combination alternating stress fatigue strength theory. An example calculation in practice showed that if fatigue strength of boring bar is satisfied to the new fatigue strength criterion, its static strength must be satisfied. The new fatigue strength criterion can be used in analyzing the boring bar’s fatigue strength on both complicated working conditions and also single working conditions. The mechanism of failure and destruction of boring bar on BTA deep hole drilling in generally actual working conditions were studied in this paper which are helpful to promote the service life cycle of boring bar in practice. Some rules are also derived to assess the dynamic performance of working boring bar, which structure parameters will be selected reasonably according to it.

People make sense of their internal experiences by attributing them to objects (I am excited because he is here). This attribution decision influences one’s opinion of the object (I like him). Misattribution occurs when the internal experience is triggered by one object (a prime), but attributed to another (a target). The present research used the Affect Misattribution Procedure to examine the influence of conceptual overlap between the prime and the target on misattribution of valenced internal experiences. For instance, would people misattribute the pleasure activated by a flower prime to a target flower more than to a person? We argue that the valence of the internal experience does not enter the attribution process alone, but is rather accompanied by semantic properties related to the object that generated the experience. Consequently, misattribution occurs more when prime and target are conceptually similar. Four experiments (Total N = 3,183) supported that prediction, using diverse primes and targets. The results suggest that the semantic properties of the internal experience help guide the attribution process.

Natural zeolite used as a partial replacement for cement has been studied extensively in terms of the mechanical properties and the durability of concrete, but its effect on the bond between the reinforcing bar and the concrete — the basis of the anchorage length and of the composite action of a reinforced concrete member — has not been reported so far. In this study, 64 pull-out specimens were cast and tested on 150 × 300 mm cylinders in which the bonded length was concentrated at mid-height. The variables were two strength classes (water-to-binder ratios of 0.47 and 0.30), four replacement levels of zeolite by weight of binder (0, 10, 20 and 30 %), two diameters of deformed bar (16 and 22 mm, with a yield stress of 400 MPa) and four bonded lengths (2.5, 5, 7.5 and 10 times the bar diameter). The results showed that the failure mode depends on the cover-to-diameter ratio alone: all 24 specimens with the 22 mm bar (cover-to-diameter ratio of 2.88) failed by splitting of the concrete, whereas the specimens with the 16 mm bar (ratio of 4.22) failed either by pull-out or by yielding of the bar. In the high-strength concrete, a 20 % replacement of zeolite increased the bond strength by up to 17.4 % (16 mm bar) and 19.0 % (22 mm bar), and the highest measured bond strength was 34.0 MPa. In the normal-strength concrete, the bond strength decreased approximately in proportion to the change in compressive strength. When the bond strength is normalized with respect to the square root of the compressive strength, the zeolite-bearing normal-strength mixtures do not differ significantly from the control mixture (mean of -3 to 0 %), while the zeolite-bearing high-strength mixtures consistently outperform the control (mean of +2.5 to +6.6 % and a maximum of +9.8 %). Zeolite therefore does not impair the bond mechanism and, in high-strength concrete, it slightly improves the quality of the bar-to-concrete interface in addition to increasing the compressive strength. A comparison with the fib MC2010 bond model showed that the pulled-out specimens reached 1.2 to 1.7 times the 2.5√fcm bound and the split specimens 0.5 to 1.0 times that bound. In the zeolite-bearing high-strength concrete, a bonded length of 5 times the diameter was sufficient to yield the 16 mm bar.