Pull-Out Strength of Screws in Screw Chases: Part 2

2016 ◽  
Vol 710 ◽  
pp. 121-126
Author(s):  
James C. LaBelle ◽  
J. Randolph Kissell ◽  
Tanya A. Dolby
Keyword(s):  
Stainless Steel ◽  
Cross Section ◽  
Wind Load ◽  
Structural Behavior ◽  
Pull Out ◽  
Stainless Steel Screws ◽  
Aluminum Profiles ◽  
Pull Out Strength

This paper (Part 2 of 2) presents a study of the structural behavior of tension-loaded screws installed in screw chases in extruded aluminum profiles. This connection is commonly used to resist outward wind load on glass in curtainwalls and skylights. See Part 1 for details of the pull-out testing. Two types of chase, each with 1/4 in. (6.35 mm) diameter stainless steel screws were used: a flat chase with AB tapping screws (1/4-14; 14 threads per 25.4 mm) and F tapping screws (1/4-20; 20 threads per 25.4 mm), and a longitudinally ribbed chase with UNC-thread machine screws (1/4-20). The extrusions included six cross-section shapes (three with flat chases and three with ribbed chases) and three alloy-tempers.

Pull-Out Strength of Screws in Screw Chases: Part 1

2016 ◽  
Vol 710 ◽  
pp. 115-120
Author(s):  
James C. LaBelle ◽  
J. Randolph Kissell ◽  
Tanya A. Dolby
Keyword(s):  
Stainless Steel ◽  
Cross Section ◽  
Wind Load ◽  
Test Results ◽  
Pull Out ◽  
Stainless Steel Screws ◽  
Screw Threads ◽  
Aluminum Profiles ◽  
Pull Out Strength

This paper presents test results and a proposed pull-out strength equation for tension-loaded screws installed in chases in extruded aluminum profiles. The screws are perpendicular to the extrusion's length. This connection is commonly used to resist outward wind load on glass in curtain walls and skylights. Two types of chase, each with 1/4 in. (6.35 mm) diameter 300 series stainless steel screws were used: a flat chase with AB tapping screws (1/4-14; 14 threads per 25.4 mm) and F tapping screws (1/4-20; 20 threads per 25.4 mm), and a longitudinally ribbed chase with UNC-thread machine screws (1/4-20). The extrusions included six cross-section shapes (three with flat chases and three with ribbed chases) and three alloy-tempers. Pull-out tests of 150 single screws were conducted. The Aluminum Design Manual [1] does not include pull-out strength equations for screws in chases; this research was intended to develop such equations. Pull-out strength increased with an increase in engaged length of screw threads with the chase. The shape and dimensions of the chase also affected the pull-out strength.

First and Second Order Elastoplastic Analyses of Thin-Walled Metal Members using Generalized Beam Theory

2018 ◽  
Author(s):  
Miguel Abambres
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Cross Section ◽  
Beam Theory ◽  
Second Order ◽  
Flow Rule ◽  
Non Linear ◽  
Thin Walled ◽  
Shell Finite Element ◽  
Generalized Beam Theory

Original Generalized Beam Theory (GBT) formulations for elastoplastic first and second order (postbuckling) analyses of thin-walled members are proposed, based on the J2 theory with associated flow rule, and valid for (i) arbitrary residual stress and geometric imperfection distributions, (ii) non-linear isotropic materials (e.g., carbon/stainless steel), and (iii) arbitrary deformation patterns (e.g., global, local, distortional, shear). The cross-section analysis is based on the formulation by Silva (2013), but adopts five types of nodal degrees of freedom (d.o.f.) – one of them (warping rotation) is an innovation of present work and allows the use of cubic polynomials (instead of linear functions) to approximate the warping profiles in each sub-plate. The formulations are validated by presenting various illustrative examples involving beams and columns characterized by several cross-section types (open, closed, (un) branched), materials (bi-linear or non-linear – e.g., stainless steel) and boundary conditions. The GBT results (equilibrium paths, stress/displacement distributions and collapse mechanisms) are validated by comparison with those obtained from shell finite element analyses. It is observed that the results are globally very similar with only 9% and 21% (1st and 2nd order) of the d.o.f. numbers required by the shell finite element models. Moreover, the GBT unique modal nature is highlighted by means of modal participation diagrams and amplitude functions, as well as analyses based on different deformation mode sets, providing an in-depth insight on the member behavioural mechanics in both elastic and inelastic regimes.

scholarly journals The effect of tissue culture on suture holding strength and degradation in canine tendon

2009 ◽  
Vol 34 (5) ◽  
pp. 643-650 ◽  
Author(s):  
H. OMAE ◽  
C. ZHAO ◽  
Y.-L. SUN ◽  
M. E. ZOBITZ ◽  
S. L. MORAN ◽  
...  
Keyword(s):  
Tissue Culture ◽  
Tensile Load ◽  
Flexor Digitorum Profundus ◽  
Tendon Suture ◽  
Pull Out ◽  
Culture Model ◽  
Static Tensile ◽  
Tissue Culture Model ◽  
Flexor Digitorum ◽  
Pull Out Strength

The purpose of this study was to assess tendon metabolism and suture pull-out strength after simple tendon suture in a tissue culture model. One hundred and twelve flexor digitorum profundus tendons from 28 dogs were cultured for 7, 14, or 21 days with or without a static tensile load. In both groups increased levels of matrix metalloproteinase (MMP) mRNA was noted. Suture pull-out strength did not decrease during tissue culture. While the presence of a static load had no effect on the pull-out strength, it did affect MMP mRNA expression. This tissue culture model could be useful in studying the effect of factors on the tendon-suture interface.

Evaluation of the Tube to Tubesheet Joining Process in an AL6XN® Feedwater Heater

2017 ◽  
Author(s):  
Eric Svensson ◽  
Michael Catapano
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Cooling Water ◽  
Intimate Contact ◽  
Pull Out ◽  
Digital Microscope ◽  
304 Austenitic Stainless Steel ◽  
Type 304 ◽  
Tube Expansion ◽  
Joining Process

Type 304 austenitic stainless steel is the most common tube material utilized for nuclear feedwater heaters, however, some utilities have experienced problems with Stress Corrosion Cracking (SCC), especially when they utilize brackish cooling water and have experienced condenser tube leaks. This has forced some utilities to explore other options when it comes to high pressure feedwater heaters (HP FWH) tubing materials. AL6XN® is considered a “super” stainless steel that is resistant to (SCC), however, it is not immune (AL6XN is a trademark of ATI Technologies). Based on the relative inexperience and unknowns related to the use of AL6XN tubing in high pressure, nuclear feedwater heater applications, a detailed mock-up procedure was outlined as part of the replacement heater specification which would allow the evaluation of the tube to tubesheet joining processes. Since AL6XN can still be affected by SCC; steps were taken in order to minimize the imposed stress levels and any potential for the inadvertent inclusion of contaminants during the fabrication steps at the tube mill and at the feedwater heater Manufacturer’s shop. The desire to minimize stresses also applies at the tube to tubesheet joint, therefore, it was desired not to stress the tube more than absolutely necessary in achieving a reliable, leak tight joint. The mock-up details and procedures were therefore generated with these objectives in mind, so as to give consideration for the ability to check different configurations in order to determine the most efficient tube to tubesheet joining process. Several tubes in the mock-up were subjected to a pull out test in order to quantify the joint strength in the different configurations. The mockup was then sectioned and inspected under a digital microscope to verify intimate contact between the tube and the tubesheet. Once the optimal procedure was identified, four identical HP FWHs were constructed utilizing AL6XN tubing. During heater production, over 30,000 tube ends were expanded, however, two tubes were identified to have failures as part of the tube expansion process. This paper shall describe the procedures utilized in developing and analyzing the tubesheet mock-up as well the actions taken to identify the root causes of the tube failures.

Springback law of high-strength 21-6-9 stainless steel tube in numerical control bending under different process parameters

2015 ◽  
Vol 231 (10) ◽  
pp. 1783-1792 ◽  
Author(s):  
Jun Fang ◽  
Shiqiang Lu ◽  
Kelu Wang ◽  
Zhengjun Yao
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
Cross Section ◽  
Process Parameters ◽  
High Strength ◽  
Steel Tube ◽  
Numerical Control ◽  
Stainless Steel Tube ◽  
Outer Diameter ◽  
The Cross

In order to achieve the precision bending deformation, the effects of process parameters on springback behaviors should be clarified preliminarily. Taking the 21-6-9 high-strength stainless steel tube of 15.88 mm × 0.84 mm (outer diameter × wall thickness) as the objective, the multi-parameter sensitivity analysis and three-dimensional finite element numerical simulation are conducted to address the effects of process parameters on the springback behaviors in 21-6-9 high-strength stainless steel tube numerical control bending. The results show that (1) springback increases with the increasing of the clearance between tube and mandrel Cm, the friction coefficient between tube and mandrel fm, the friction coefficient between tube and bending die fb, or with the decreasing of the mandrel extension length e, while the springback first increases and then remains unchanged with the increasing of the clearance between tube and bending die Cb. (2) The sensitivity of springback radius to process parameters is larger than that of springback angle. And the sensitivity of springback to process parameters from high to low are e, Cb, Cm, fb and fm. (3) The variation rules of the cross section deformation after springback with different Cm, Cb, fm, fb and e are similar to that before springback. But under same process parameters, the relative difference of the most measurement section is more than 20% and some even more than 70% before and after springback, and a platform deforming characteristics of the cross section deformation is shown after springback.

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