Failure Envelopes for Composite Fiber Reinforced Pipe Elbows Subject to Combined Loading—A Numerical Assessment

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Duncan Camilleri ◽  
Brian Ellul
Keyword(s):  
Damage Mechanics ◽  
Oil And Gas ◽  
Failure Load ◽  
Numerical Models ◽  
Bending Moment ◽  
Composite Fiber ◽  
Combined Loading ◽  
Fiber Reinforced ◽  
Pressure Loading ◽  
Failure Loads

Composite pipes are currently being used in a multitude of applications varying from civil to oil and gas applications. Pipes are generally connected together by means of pipe elbows that in turn are subjected to bending moment and pressure loading. This study looks into the effect of combined loading on the first ply and ultimate failure load of pipe elbows. The influence of pressure loading followed by a bending moment versus first applying bending moment followed by subsequent pressure loading, on the ultimate catastrophic failure load, is investigated through numerical models. The combined bending moment and pressure load ramping is also studied. Design by analysis finite element damage mechanics numerical methods are applied to investigate post first ply failure (FPF) and stress redistribution. The study shows that different loading combinations can give rise to different damage mechanisms and ultimately failure loads. A safe design load envelope for different fiber-reinforced pipe elbows based on FPF and ultimate catastrophic load is identified and discussed.

Composite Fibre Reinforced Pipe Elbows Subject to Combined Loading

2017 ◽  
Author(s):  
Duncan Camilleri ◽  
Brian Ellul
Keyword(s):  
Numerical Methods ◽  
Damage Mechanics ◽  
Oil And Gas ◽  
Bending Moment ◽  
Combined Loading ◽  
Pressure Loading ◽  
Pipe Elbow ◽  
Failure Loads ◽  
Ultimate Failure ◽  
Composite Pipes

Composite pipes are currently being used in a multitude of applications varying from civil to oil and gas applications. Pipes are generally connected together by means of pipe elbows that in turn are subjected to bending moment and pressure loading. This study looks into the effect of combined loading on the first ply and ultimate failure load of pipe elbows. The influence of pressure loading followed by a bending moment versus firstly applying bending moment followed by subsequent pressure loading, on the ultimate catastrophic failure, is investigated through numerical methods. The combined bending moment and pressure load ramping is also studied. Design by analysis finite element damage mechanics numerical methods are applied to investigate post first ply failure and stress redistribution. The study shows that different loading combinations can give rise to different damage mechanisms and ultimately failure loads. A safe design load envelope for a typical fibre-reinforced pipe elbow and following first ply failure and ultimate catastrophic is established and discussed.

Prediction of Inelastic Behavior of Composite Laminates Using Multi-Surface Continuum Damage-Plasticity

2008 ◽  
Vol 47-50 ◽  
pp. 773-776 ◽  
Author(s):  
Bijan Mohammadi ◽  
Hossein Hosseini-Toudeshky ◽  
Mohammad Homayoun Sadr-Lahidjani ◽  
Shahram Aivazzadeh
Keyword(s):  
Composite Laminates ◽  
Damage Mechanics ◽  
Failure Load ◽  
Internal Variable ◽  
Damage Analysis ◽  
Continuum Damage ◽  
Inelastic Behavior ◽  
Surface Plasticity ◽  
Plastic Damage ◽  
Failure Loads

The recently performed investigations in continuum plastic-damage analysis of composite laminates by the authors showed that using a single hardening internal variable for damage and plasticity surfaces may prone to significant errors in response and failure load for some lay-ups. In this paper, the new technique of coupled continuum plastic-damage mechanics including multisurface dissipation potentials are employed to improve the results. The response and failure loads of the laminated composites with different lay-ups are predicted using elastic, damage, and damageplasticity conditions with single and multi surface plasticity and compared with the available experimental results.

DYNAMIC FAILURE OF A SPOT WELD IN LAP–SHEAR TESTS UNDER COMBINED LOADING CONDITIONS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5527-5532 ◽  
Author(s):  
J. H. SONG ◽  
J. W. HA ◽  
H. HUH ◽  
J. H. LIM ◽  
S. H. PARK
Keyword(s):  
Failure Load ◽  
Spot Weld ◽  
Combined Loading ◽  
Dynamic Failure ◽  
Failure Model ◽  
Dynamic Effects ◽  
Shear Tests ◽  
Loading Rates ◽  
Lap Shear ◽  
Failure Loads

This paper is concerned with the evaluation of the dynamic failure load in the lap-shear tests of a spot weld. Dynamic lap-shear tests of a spot weld in SPRC340R were conducted with different tensile speeds ranging from 5×10-5 m/sec to 5.0 m/sec. Dynamic effects on the failure load of a spot weld are examined based on the experimental data. Experimental results indicate that failure strength increases with increasing loading rates. Finite element analyses of dynamic lap-shear tests were also performed considering the failure of a spot weld. A spot weld is modeled with a beam element and dynamic failure model is utilized in order to describe the failure of a spot weld in the simulation. The failure loads obtained from the analyses are compared to those from the lap-shear tests. The comparison shows that the failure loads obtained from the analyses are close in consistence with those obtained from the experiments.

EFFECT OF TENSILE SPEED ON THE FAILURE LOAD OF A SPOT WELD UNDER COMBINED LOADING CONDITIONS

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1469-1474 ◽  
Author(s):  
JUNG-HAN SONG ◽  
HOON HUH ◽  
JI-HO LIM ◽  
SUNG-HO PARK
Keyword(s):  
Failure Load ◽  
Rate Sensitivity ◽  
Shear Loading ◽  
Spot Weld ◽  
Combined Loading ◽  
Failure Behavior ◽  
Loading Conditions ◽  
Dynamic Failure ◽  
Shear Loads ◽  
Failure Loads

This paper is concerned with the evaluation of the dynamic failure load of the spot weld under combined axial and shear loading conditions. The testing fixture are designed to impose the combined axial and shear load on the spot weld. Using the proposed testing fixtures and specimens, quasi-static and dynamic failure tests of the spot weld are conducted with seven different combined loading conditions. The failure load and failure behavior of the spot weld are investigated with different loading conditions. Dynamic effects on the failure load of the spot weld, which is critical for structural crashworthiness, are also examined based on the experimental data. In order to evaluate the effect of the strain rate on the failure contour of the spot weld under combined axial and shear loads, the failure loads measured from the experiment are decomposed into the two components along the axial and shear directions. Experimental results indicate that the failure contour is expanded with increasing strain rates according to the rate sensitivity of the ultimate stress for welded material.

Effect of Tensile Speed on the Failure Load of Laser Welding under Combined Loading Conditions

2013 ◽  
Vol 535-536 ◽  
pp. 489-492 ◽  
Author(s):  
Jiwoong Ha ◽  
Hoon Huh ◽  
Keunhwan Pack ◽  
Soonkeun Jang
Keyword(s):  
Failure Load ◽  
Pure Shear ◽  
Shear Loading ◽  
Combined Loading ◽  
Failure Behavior ◽  
Loading Conditions ◽  
Welding Condition ◽  
Shear Loads ◽  
Laser Welds ◽  
Failure Loads

This paper is concerned with the failure characteristics and the failure loads of laser welds in a SPRC340 1.2t steel sheet under combined normal and shear loading conditions. The quasi-static and dynamic failure tests were carried out under nine different combined normal and shear loads including a pure-normal load and a pure-shear load. Especially for the pure-shear condition, a testing fixture was newly designed in order to evaluate the strength of a laser-welded region fabricated by the same welding condition as a two-layered lap joint. The failure load and the failure behavior of laser welds were investigated in each loading condition. Dynamic effects on the failure load of laser welds, which are critical for structural crashworthiness, were also examined based on the experimental data. In order to evaluate the effect of the strain rate on the failure contour of laser welds under the combined normal and shear loads, the failure loads measured from the experiment were decomposed into two components along the normal and shear directions.

scholarly journals Influence of Tensile Speeds on the Failure Loads of the DP590 Spot Weld under Various Combined Loading Conditions

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Jung Han Song ◽  
Hoon Huh
Keyword(s):  
Failure Load ◽  
Shear Loading ◽  
Spot Weld ◽  
Combined Loading ◽  
Failure Behavior ◽  
Shear Load ◽  
Loading Conditions ◽  
Dynamic Failure ◽  
Failure Loads ◽  
Similar Dynamic

This paper is concerned with the evaluation of the dynamic failure load of the spot weld under combined axial and shear loading conditions. The testing fixture is designed to impose the combined axial and shear load on the spot weld. Using the proposed testing fixtures and specimens, quasi-static and dynamic failure tests of the spot weld are conducted with seven different combined loading conditions. The failure load and failure behavior of the spot weld are investigated with different loading conditions. Effect of tensile speeds on the failure load of the spot weld, which is critical for structural crashworthiness, is also examined based on the experimental data. The failure loads measured from the experiment are decomposed into the two components along the axial and shear directions and failure contours are plotted with different loading speeds. Dynamic sensitivities of failure loads with various combined loading conditions were also analyzed. Experimental results indicate that the failure contour is expanded with increasing loading speeds and failure loads show similar dynamic sensitivity with respect to the loading angles.

The Influence of Loads Superposition, Deterioration Due to Cracks and Residual Stresses on the Strength of Tubular Junction

2017 ◽  
Vol 68 (6) ◽  
pp. 1267-1273
Author(s):  
Valeriu V. Jinescu ◽  
Angela Chelu ◽  
Gheorghe Zecheru ◽  
Alexandru Pupazescu ◽  
Teodor Sima ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Residual Stresses ◽  
Bending Moment ◽  
Combined Loading ◽  
Torsional Moment ◽  
Calculation Methods ◽  
State Of Stress ◽  
Cracked Structures ◽  
Total Participation ◽  
Theoretical Results

In the paper the interaction of several loads like pressure, axial force, bending moment and torsional moment are analyzed, taking into account the deterioration due to cracks and the influence of residual stresses. A nonlinear, power law, of structure material is considered. General relationships for total participation of specific energies introduced in the structure by the loads, as well as for the critical participation have been proposed. On these bases: - a new strength calculation methods was developed; � strength of tubular cracked structures and of cracked tubular junction subjected to combined loading and strength were analyzed. Relationships for critical state have been proposed, based on dimensionless variables. These theoretical results fit with experimental date reported in literature. On the other side stress concentration coefficients were defined. Our one experiments onto a model of a pipe with two opposite nozzles have been achieved. Near one of the nozzles is a crack on the run pipe. Trough the experiments the state of stress have been obtained near the tubular junction, near the tip of the crack and far from the stress concentration points. On this basis the stress concentration coefficients were calculated.

Effect of Torsion on Collapse Bending Moment for 24-Inch Diameter Schedule 80 Pipes With Wall Thinning

2012 ◽  
Author(s):  
Kunio Hasegawa ◽  
Yinsheng Li ◽  
Bostjan Bezensek ◽  
Phuong Hoang
Keyword(s):  
Power Plants ◽  
Bending Moment ◽  
Combined Loading ◽  
Bending Moments ◽  
Compressive Stresses ◽  
Wall Thinning ◽  
Nominal Thickness ◽  
Calculation Results ◽  
Loading Modes ◽  
Local Wall Thinning

Piping items in power plants may experience combined bending and torsion moments during operation. Currently, there is a lack of guidance in the ASME B&PV Code Section XI for combined loading modes including pressure, torsion and bending. Finite element analyses were conducted for 24-inch diameter Schedule 80 pipes with local wall thinning subjected to tensile and compressive stresses. Plastic collapse bending moments were calculated under constant torsion moments. From the calculation results, it can be seen that collapse bending moment for pipes with local thinning subjected to tensile stress is smaller than that subjected to compressive stress. In addition, equivalent moment is defined as the root the sum of the squares of the torsion and bending moments. It is found that the equivalent moments can be approximated with the pure bending moments, when the wall thinning length is equal or less than 7.73R·t for the wall thinning depth of 75% of the nominal thickness, where R is the mean radius and t is the wall thickness of the pipe.

Prediction Method for Plastic Collapse of Pipes Subjected to Combined Bending and Torsion Moments

2010 ◽  
Author(s):  
Yinsheng Li ◽  
Kunio Hasegawa ◽  
Phuong H. Hoang ◽  
Bostjan Bezensek
Keyword(s):  
Entire Range ◽  
Estimation Method ◽  
Prediction Method ◽  
Bending Moment ◽  
Combined Loading ◽  
Plastic Collapse ◽  
Finite Element Analyses ◽  
Pure Torsion ◽  
Stainless Steel Pipe ◽  
Service Inspection

When a crack is detected in a pipe during in-service inspection, the failure estimation method given in the codes such as ASME Boiler and Pressure Vessel Code Section XI non-mandatory Appendix C or JSME S NA-1-2008 Appendix E-8 can be applied to assess the integrity of the pipe. In the current editions of these codes, the failure estimation method is provided for bending moment and pressure. Torsion load is assumed to be relatively small and is not considered in the method. In this paper, finite element analyses are conducted for 24-inch stainless steel pipe with a circumferential surface crack subjected to the combined bending and torsion moments, focusing on large and pure torsion moments. Based on the analysis results, a prediction method for plastic collapse under the combined loading conditions of bending and torsion is proposed for the entire range of torsion moments.

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