Behavior of eccentrically loaded welded hollow spherical joints after elevated-temperature exposure

Welded hollow spherical joint is an extremely widely used connection pattern in space lattice structures. Understanding the behavior of the welded hollow spherical joint after elevated-temperature exposure is critical for the fire damage assessment of the entire space lattice structures. In this study, both experimental and numerical studies were conducted to reveal the mechanical behavior of eccentrically loaded welded hollow spherical joints subjected to eccentric loads after cooling from three elevated temperatures up to 1000°C, wherein two different methods were considered, namely, air and water cooling. Associate mechanical performance, such as load versus longitudinal displacement and load versus steel tube rotation responses, initial stiffness, load-bearing capacities, and strain development, were obtained and further analyzed. The results showed that the behavior of welded hollow spherical joints began to change when the exposure temperatures exceeded 600°C, with obvious reductions in both stiffness and strength. In addition, the influences of different cooling methods were significant. The joints cooled by water generally presented higher load-bearing capacities than those cooled by air. Furthermore, three-dimensional finite element analysis was conducted via ABAQUS software. After validating the finite element model against experimental results, parametric studies were performed and a practical formula was proposed to calculate the load-bearing capacity of welded hollow spherical joints subjected to eccentric load after elevated-temperature exposure.

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Finite element analysis of a personalized femoral scaffold with designed microarchitecture

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1243/09544119jeim633 ◽

2009 ◽

Vol 224 (7) ◽

pp. 877-889 ◽

Cited By ~ 4

Author(s):

P Pandithevan ◽

G Saravana Kumar

Keyword(s):

Mechanical Properties ◽

Finite Element ◽

Computer Aided Design ◽

Strain State ◽

Mechanical Performance ◽

Physiological Stress ◽

Tissue Growth ◽

Bone Tissue Regeneration ◽

Load Bearing ◽

Ct Data

Tissue engineering scaffolds with intricate and controlled internal structure can be realized using computer-aided design (CAD) and layer manufacturing (LM) techniques. Design and manufacturing of scaffolds for load-bearing bone sites should consider appropriate biocompatibile materials with interconnected porosity, surface properties, and sufficient mechanical properties that match the surrounding bone, in order to provide adequate support, and to mimic the physiological stress—strain state so as to stimulate new tissue growth. The authors have previously published methods for estimating subject- and site-specific bone modulus using computed tomography (CT) data, CAD, and process planning for LM of controlled porous scaffolds. This study evaluates the mechanical performance of the designed porous hydroxyapite scaffolds in load-bearing sites using a finite element (FE) approach. A subject-specific FE analysis using femoral, defect site geometry and anisotropic material assignment based on CT data is employed. Mechanical behaviour of the femur with scaffold in stance-phase gait loading, which has been shown experimentally to produce clinically relevant results, is analysed. The comparison of results with simulation of healthy femur shows an overall correspondence in stress and strain state which will provide optimized mechanical properties for avoiding stress shielding, and adequate strength to avoid failure risk and for active bone tissue regeneration.

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Elevated Temperature Properties of Maraging Steel Plates and Welds

Journal of Basic Engineering ◽

10.1115/1.3425216 ◽

1971 ◽

Vol 93 (2) ◽

pp. 218-224

Author(s):

N. Kenyon ◽

E. P. Sadowski ◽

P. P. Hydrean

Keyword(s):

Elevated Temperature ◽

Maraging Steel ◽

Elevated Temperatures ◽

High Strength Steels ◽

High Strength ◽

Steel Plates ◽

Maraging Steels ◽

Gas Tungsten Arc ◽

Temperature Exposure ◽

Rupture Behavior

The creep rupture behavior, and the effects of elevated temperature exposure in air and hydrogen on the subsequent room temperature properties of a 12 percent Ni-5 percent Cr-3 percent Mo maraging steel are described. Tests have been made on several heats of plate and on gas tungsten-arc, gas metal-arc, and electroslag welds. On the basis of the results obtained, maraging steels offer promise as high-strength steels for service at elevated temperatures.

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Study on Tensile Properties of CFRP Plates under Elevated Temperature Exposure

Materials ◽

10.3390/ma12121995 ◽

2019 ◽

Vol 12 (12) ◽

pp. 1995 ◽

Cited By ~ 3

Author(s):

Yongxin Yang ◽

Yanju Jiang ◽

Hongjun Liang ◽

Xiaosan Yin ◽

Yue Huang

Keyword(s):

Tensile Strength ◽

Elastic Modulus ◽

Elevated Temperature ◽

Tensile Properties ◽

Failure Mode ◽

Elevated Temperatures ◽

Strain Curve ◽

Effect Of Temperature ◽

Temperature Exposure ◽

The Impact

Elevated temperature exposure has a negative effect on the performance of the matrix resin in Carbon Fiber Reinforced Plastics (CFRP) plates, whereas limited quantitative research focuses on the deteriorations. Therefore, 30 CFRP specimens were designed and tested under elevated temperatures (10, 30, 50, 70, and 90 °C) to explore the degradations in tensile properties. The effect of temperature on the failure mode, stress-strain curve, tensile strength, elastic modulus and elongation of CFRP plates were investigated. The results showed that elevated temperature exposure significantly changed the failure characteristics. When the exposed temperature increased from 10 °C to 90 °C, the failure mode changed from the global factures in the whole CFRP plate to the successive fractures in carbon fibers. Moreover, with temperatures increasing, tensile strength and elongation of CFRP plates decreases gradually while the elastic modulus shows negligible change. Finally, the results of One-Way Analysis of Variance (ANOVA) show that the degradation of the tensile strength of CFRP plates was due to the impact of elevated temperature exposure, rather than the test error.

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Assessment of mechanical strength of nano silica concrete (NSC) subjected to elevated temperatures

Journal of Structural Fire Engineering ◽

10.1108/jsfe-10-2017-0041 ◽

2019 ◽

Vol 10 (1) ◽

pp. 90-109 ◽

Cited By ~ 4

Author(s):

Hala Mohamed Elkady ◽

Ahmed M. Yasien ◽

Mohamed S. Elfeky ◽

Mohamed E. Serag

Keyword(s):

Elevated Temperature ◽

Bond Strength ◽

Elevated Temperatures ◽

Mechanical Performance ◽

Mechanical Tests ◽

Nano Silica ◽

Content Type ◽

Post Exposure ◽

Concrete Mix ◽

Bond Strengths

Purpose This paper aims to inspect the effect of indirect elevated temperature on the mechanical performance of nano silica concrete (NSC). The effect on both compressive and bond strengths is studied. Pre- and post-exposure to elevated temperature ranges of 200 to 600°C is examined. A range covered by three percentages of 1.5, 3 and 4.5 per cent nano silica (NS) in concrete mixes is tested. Design/methodology/approach Pre-exposure mechanical tests (normal conditions – room temperature), using 3 per cent NS in the concrete mix, led to the highest increase in both compressive and bond strengths (43 per cent and 38.5 per cent, respectively), compared to the control mix without NS (based on 28-day results). It is worth noticing that adding NS to the concrete mixes does not have a significant effect on improving early-age strength. Besides, permeability tests are performed on NSC with different NS ratios. NS improved the concrete permeability for all tested percentages of NS. The maximum reduction is accompanied by the maximum percentage used (4.5 per cent NS in the NSC mix), reducing permeability to half the value of the concrete mix without NS. As for post-exposure to elevated-temperature mechanical tests, NSC with 1.5 per cent NS exhibited the lowest loss in strength owing to indirect heat exposure of 600°C; the residual compressive and bond strengths are 73 per cent and 35 per cent, respectively. Findings The dispersion technique of NS has a key role in NSC-distinguished mechanical performance with NSC having lower NS percentages. NS significantly improved bond strength. NS has a remarkable effect on elevated temperature endurance. The bond strength of NSC exposed to elevated temperatures suffered faster deterioration than compressive strength of the exposed NSC. Research limitations/implications A special scale factor needs to be investigated for the NSC. Originality/value Although a lot of effort is placed in evaluating the benefits of using nano materials in structural concrete, this paper presents one of the first outcomes of the thermal effects on concrete mixes with NS as a partial cement replacement.

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The Influence of the Roller Forming Path on the Neck-Spinning Process of Tube at Elevated Temperature

Volume 3: Design and Manufacturing ◽

10.1115/imece2011-62434 ◽

2011 ◽

Cited By ~ 1

Author(s):

Chi-Chen Huang ◽

Jung-Chung Hung ◽

Cheng-Chan Lo ◽

Chia-Rung Lin ◽

Chinghua Hung

Keyword(s):

Finite Element ◽

Elevated Temperature ◽

Elevated Temperatures ◽

Thickness Distribution ◽

Optimization Technique ◽

Element Model ◽

Strain Rates ◽

Forming Process ◽

Tube Spinning ◽

Spinning Process

The tube spinning process is a metal forming process used in the manufacture of axisymmetric products, and has been widely used in various applications. In this paper, the neck-spinning process was applied to form the neck part of the tube end at an elevated temperature. The spun tube was used as a high pressure CO2 vessel, which is a component of motorcycle airbag jackets. An uneven surface will occur on the tube surface if the thickness distribution of the tube is not uniform after the neck-spinning process. This is because different thicknesses result from different contractions during the cooling stage. For this reason, the aim of this research was to numerically investigate the roller forming path to improve the thickness distribution of the tube during the neck-spinning process. The finite element method was used to simulate the neck-spinning process of the tube at an elevated temperature. For the construction of the material model, special uni-axial tensile tests were conducted at elevated temperatures and various strain rates, because the material is sensitive to strain rates at high temperatures. This paper compares the experimental and simulation results of the thickness distribution and the outer contour of the spun tube. The validated finite element model was used to investigate the influence of the roller forming path on the thickness distribution of the tube. The thickness distribution of the tube formed by a curved path was found to be more uniform than for the tube formed by a straight path. Finally, the optimization technique was used to find the optimal forming path, and the optimal result was verified experimentally.

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An integrated experimental and finite element approach for wrinkling limit prediction of Inconel 718 alloy at elevated temperatures

The Journal of Strain Analysis for Engineering Design ◽

10.1177/03093247211043098 ◽

2021 ◽

pp. 030932472110430

Author(s):

Gauri Mahalle ◽

Nitin Kotkunde ◽

Amit Kumar Gupta ◽

Swadesh Kumar Singh

Keyword(s):

Finite Element ◽

Elevated Temperature ◽

Inconel 718 ◽

Room Temperature ◽

Elevated Temperatures ◽

Functional Requirements ◽

Inconel 718 Alloy ◽

Different Temperatures ◽

Post Buckling ◽

Element Approach

Wrinkling is generally induced because of metal instability and considered as an undesirable defect in sheet metal forming processes. Wrinkling leads to severe influence on functional requirements and aesthetic appeal of final component. Thus, the present research is mainly dedicated on the experimental and numerical analysis for wrinkling behavior prediction of Inconel 718 alloy at elevated temperature conditions. Initially, Yoshida buckling tests (YBT) have been conducted to investigate wrinkling tendencies of Inconel 718 alloy from room temperature (RT) to 600°C by an interval of 200°C. Subsequently, Finite Element (FE) analysis of YBT has been performed to analyze post buckling behavior. Critical strain values at onset of wrinkling are determined and strain based wrinkling limit curves (ε-WLCs) are plotted at different temperatures. In-plane principal strains are transferred to effective plastic strain (EPS) versus triaxiality (η) space to differentiate the transformation between safe and wrinkling instability. Finally, complete forming behavior of alloy is represented by means of fracture, forming, and wrinkling limit curves. The gap between forming and wrinkling limit curves at elevated temperature is ∼1.5 times higher than that at room temperature.

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Mechanical Performance of High-Strength Sustainable Concrete under Fire Incorporating Locally Available Volcanic Ash in Central Harrat Rahat, Saudi Arabia

Materials ◽

10.3390/ma14010021 ◽

2020 ◽

Vol 14 (1) ◽

pp. 21

Author(s):

Muhammad Nasir Amin ◽

Kaffayatullah Khan

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Elevated Temperature ◽

Volcanic Ash ◽

Elevated Temperatures ◽

Mechanical Performance ◽

High Strength ◽

Pulse Velocity ◽

Sustainable Concrete ◽

Harrat Rahat

This study investigated the effect of elevated temperatures on the mechanical properties of high-strength sustainable concrete incorporating volcanic ash (VA). For comparison, control and reference concrete specimens with fly ash (FA) were also cast along with additional specimens of VA and FA containing electric arc furnace slag (EAFS). Before thermal exposure, initial tests were performed to evaluate the mechanical properties (compressive strength, tensile strength, and elastic modulus) of cylindrical concrete specimens with aging. Additionally, 91 day moist-cured concrete specimens, after measuring their initial weight and ultrasonic pulse velocity (UPV), were exposed up to 800 °C and cooled to air temperature. Subsequently, the weight loss, residual UPV, and mechanical properties of concrete were measured with respect to exposure temperature. For all concrete specimens, test results demonstrated a higher loss of weight, UPV, and other mechanical properties under exposure to higher elevated temperature. Moreover, all the results of concrete specimens incorporating VA were observed before and after exposure to elevated temperature as either comparable to or slightly better than those of control and reference concrete with FA. According to the experimental results, a correlation was developed between residual UPV and residual compressive strength (RCS), which can be used to assess the RCS of fire-damaged concrete (up to 800 °C) incorporating VA and EAFS.

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Experimental and Numerical Analysis of Fatigue Life of Aluminum Al 2024-T351 at Elevated Temperature

Metals ◽

10.3390/met10121581 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1581

Author(s):

Shahan Mazlan ◽

Noorfaizal Yidris ◽

Seyed Saeid Rahimian Koloor ◽

Michal Petrů

Keyword(s):

Finite Element ◽

Fatigue Life ◽

Elevated Temperature ◽

Yield Strength ◽

Ultimate Strength ◽

Elevated Temperatures ◽

Load Ratio ◽

High Temperature Furnace ◽

Structural Parts ◽

Al 2024

This paper presents the prediction of the fatigue life of aluminum Al 2024-T351 at room and elevated temperatures under uniaxial loading using finite element simulation. Structural parts such as fuselage, wings, aircraft turbines and heat exchangers are required to work safely at this working condition even with decreasing fatigue strength and other properties. The monotonic tensile and cyclic tests at 100 °C and 200 °C were conducted using MTS 810 servo hydraulic equipped with MTS 653 high temperature furnace at a frequency of 10 Hz and load ratio of 0.1. There was an 8% increase in the yield strength and a 2.32 MPa difference in the ultimate strength at 100 °C. However, the yield strength had a 1.61 MPa difference and 25% decrease in the ultimate strength at 200 °C compared to the room temperature. The mechanical and micro-structural behavior at elevated temperatures caused an increase in the crack initiation and crack propagation which reduced the total fatigue life. The yield strength, ultimate strength, alternating stress, mean stress and fatigue life were taken as the input in finite element commercial software, ANSYS. Comparison of results between experimental and finite element methods showed a good agreement. Hence, the suggested method using the numerical software can be used for predicting the fatigue life at elevated temperature.

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Influence of an Elevated Temperature Environment on the Tensile Mechanical Properties of a 3D Printed Thermoplastic Polymer

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2019-93589 ◽

2019 ◽

Author(s):

Jose E. Torres ◽

Otito N. Onwuzurike ◽

Amber J. W. McClung ◽

Juan D. Ocampo

Keyword(s):

Mechanical Properties ◽

Elevated Temperature ◽

Mechanical Testing ◽

Elevated Temperatures ◽

Mechanical Performance ◽

Material Behavior ◽

Experimental Program ◽

Thermoplastic Polymer ◽

3D Printed ◽

Property Changes

Abstract The purpose of this study is to examine the effects of the environment on 3D printed Polylactic Acid (PLA), a biodegradable thermoplastic polymer. The experimental program was specifically designed to explore the influence of print temperature and aging temperature on the mechanical performance of the printed material. Printing at the elevated temperatures (30–40°C) resulted in slight mechanical property changes. In order to understand which of the changes could also be caused by simply storing the materials at the elevated temperature, samples were printed at 25°C and subsequently aged (at 30–45°C) before mechanical testing. All mechanical testing was performed in standard laboratory temperature on an MTS Criterion. All of the mechanical properties were not greatly altered by printing or aging at elevated temperatures, suggesting that printing and using in extreme weather environments could be reasonable. The yield stress is not affected by storage at elevated temperatures, but is increased (or enhanced) by printing at elevated temperatures. The maximum stress is increased (or enhanced) by both aging and printing at elevated temperatures, but is accompanied by a large reduction in strain capacity. Changes that are observed in mechanical properties will be incorporated in future material models to accurately capture material behavior.

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