OS2108 Relation between fatigue strength properties and damage mechanism in GFPC using modified resin

This paper contributes to the effect of elevated temperature on the fatigue strength of common aluminum cast alloys EN AC-46200 and EN AC-45500. The examination covers both static as well as cyclic fatigue investigations to study the damage mechanism of the as-cast and post-heat-treated alloys. The investigated fracture surfaces suggest a change in crack origin at elevated temperature of 150 ∘ C. At room temperature, most fatigue tests reveal shrinkage-based micro pores as their crack initiation, whereas large slipping areas occur at elevated temperature. Finally, a modified a r e a -based fatigue strength model for elevated temperatures is proposed. The original a r e a model was developed by Murakami and uses the square root of the projected area of fatigue fracture-initiating defects to correlate with the fatigue strength at room temperature. The adopted concept reveals a proper fit for the fatigue assessment of cast Al-Si materials at elevated temperatures; in detail, the slope of the original model according to Murakami should be decreased at higher temperatures as the spatial extent of casting imperfections becomes less dominant at elevated temperatures. This goes along with the increased long crack threshold at higher operating temperature conditions.

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Evaluation of Total Ankle Arthroplasty Using Highly Crosslinked Ultrahigh-Molecular-Weight Polyethylene Subjected to Physiological Loading

Foot & Ankle International ◽

10.1177/1071100719847645 ◽

2019 ◽

Vol 40 (8) ◽

pp. 880-887 ◽

Cited By ~ 3

Author(s):

Jeffrey E. Bischoff ◽

Mehul A. Dharia ◽

Justin S. Hertzler ◽

Oliver N. Schipper

Keyword(s):

Fatigue Strength ◽

Fatigue Testing ◽

Ultrahigh Molecular Weight Polyethylene ◽

Fatigue Loading ◽

Strength Properties ◽

Total Ankle Arthroplasty ◽

Wear Properties ◽

Ankle Arthroplasty ◽

Walking Gait

Background: Highly crosslinked polyethylene (HXLPE) was developed for its superior wear properties in comparison to conventional polyethylene (CPE). Concern over fatigue resistance has prevented widespread adoption of HXLPE for use in total ankle arthroplasty (TAA). The aim of this study was to determine whether HXLPE has sufficient fatigue strength for total ankle arthroplasty under simulated physiologically relevant motion profiles and loading in the ankle. Methods: Physiologic load and motion profiles representative of walking gait were incorporated into a computational model of a semiconstrained, fixed-bearing TAA to determine the loading state with highest stresses in the HXLPE bearing. Subsequent fatigue testing to 10 million cycles (Mc) at 5600 N was performed to assess bearing strength. Results: Peak stresses in the bearing were predicted at peak axial load and peak dorsiflexion during gait, occurring near heel off. All samples withstood 10 Mc of fatigue loading at that orientation without polyethylene bearing fracture. Conclusion: HXLPE had sufficient fatigue strength to withstand 10 Mc of loading at more than 5 times body weight at the point of peak stresses during simulated gait in total ankle arthroplasty. Clinical Relevance: HXLPE may be mechanically strong enough to withstand the in vivo demands of the ankle. Improvements in wear afforded by HXLPE can be obtained without compromising sufficient polyethylene strength properties in total ankle arthroplasty.

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FATIGUE TEST OF STEEL GIRDER WEB PENETRATION DETAILS WITH A SLIT

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2014.11 ◽

2014 ◽

Vol 1 (1) ◽

Author(s):

Naoto Yoshida ◽

Masahiro Sakano ◽

Hideyuki Konishi ◽

Takashi Fujii

Keyword(s):

Fatigue Strength ◽

Fatigue Behavior ◽

Fatigue Crack Initiation ◽

Fatigue Cracking ◽

Highway Bridges ◽

Strength Properties ◽

Fatigue Tests ◽

Bottom Surface ◽

Steel Girder ◽

Propagation Behavior

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. A one-meter-long crack was detected in Yamazoe Bridge in 2006. Since a number of highway bridges with such web penetration details may exist in Japan, it is of urgent importance to understand these fatigue-strength properties. However, few fatigue tests have been reported on steel girder web penetration details. The purpose of this study is to clarify fatigue behavior of steel girder web penetration details with a slit through fatigue tests of specimens with these details. We designed and fabricated girder specimens that have steel girder web penetration details, in which cross-beam bottom flanges are connected to each top or bottom surface of a slit by welding. First, we conducted static loading tests to understand the stress distributions around web penetration details. Second, we conducted fatigue tests to examine fatigue crack initiation and propagation behavior and fatigue strength.

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THREE FACE ATTACHMENT RETROFIT AGAINST FATIGUE CRACKING AT STEEL GIRDER WEB PENETRATION

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2018.134 ◽

2018 ◽

Vol 5 (2) ◽

Author(s):

Chihiro Sakamoto ◽

Masahiro Sakano ◽

Hideyuki Konishi ◽

Takashi Fujii

Keyword(s):

Fatigue Strength ◽

Stress Concentration ◽

Stress Reduction ◽

Fatigue Cracking ◽

Highway Bridges ◽

Lower Surface ◽

Strength Properties ◽

Fatigue Tests ◽

Lower Side ◽

Steel Girder

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties. In this study, we investigate stress reduction effects of three face attachment retrofit through fatigue tests using a large girder specimen with web penetration details where cross beam lower flanges are connected to the lower surface of a slot by welding. As a result, there is very little difference between two and three face attachments about stress reduction effects, while they are more effective than one face attachment. The upper side attachment is more effective than the lower side attachment, while both side attachment is best. Two and three face both side attachments can reduce about 40% of stress concentration, while two and three face upper side attachments can reduce 50– 60%.

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