Uncertainty Quantification of Nondestructive Techniques to Verify Pipeline Material Strength

2018 ◽  
Author(s):  
Jeffrey A. Kornuta ◽  
Nicoli M. Ames ◽  
Mary W. Louie ◽  
Peter Veloo ◽  
Troy Rovella
Keyword(s):  
Tensile Strength ◽  
Material Properties ◽  
Strain Curve ◽  
Material Strength ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Empirical Constant ◽  
Modeling Uncertainties ◽  
Force Displacement ◽  
Indentation Response

The Pipeline and Hazardous Materials Safety Administration (PHMSA) Notice of Proposed Rulemaking (NPRM), with Docket No. PHMSA-2011-0023, substantially revises 49 CFR Part 191 and 192. Notable among these changes was the addition of §192.607, verification of pipeline material. This section calls for the verification of material properties of pipe and fittings located in either high consequence areas, class 3, or class 4 locations where traceable, verifiable, and complete records do not exist. Material properties include grade (yield strength, YS, and ultimate tensile strength, UTS) and chemical composition. The proposed regulations include an independent third-party validation for non-destructive testing (NDT) methods to determine material strength and require an accuracy of within ±10% of an actual strength value. Among the NDT technologies currently available to pipeline operators to estimate material strength is instrumented indentation testing (IIT). IIT is based on the principal that there exists a relationship between the indentation response of a material and its stress-strain curve. The indentation response is measured during the IIT process whereby an indenter is sequentially forced into the material during testing. The link between the indentation response and the material stress-strain curve is established often through the use of iterative Finite Element Analysis (FEA). The IIT vendor’s proprietary software performs this calculation, converting force-displacement measurements into an estimate of YS and UTS. In this study we extracted force-displacement data from IIT performed using FEA on an idealized steel. This data was then coupled with literature algorithms developed at Seoul National University (Kwon et al.). Parametric sensitivity analysis was then performed on estimated YS with respect to the algorithm parameters. Preliminary results indicate that while variations in the indenter constant, ω, used to estimate surface deformation do not significantly alter the predicted UTS or YS, the sensitivity to deviations in the empirical constant, Ψ, relating normal load to representative stress was more pronounced due to an effect on the calculated power-law constant, K. PHMSA’s NPRM accuracy requirements for NDT to establish yield and tensile strength should be driven by a rigorous understanding of material inhomogeneities, uncertainties in actual tensile strength determination, experimental uncertainty, and modeling uncertainties. The analysis performed in this paper provides part of this rigorous framework to establish realistic accuracy requirements for NDT that must drive federal rulemaking. In addition, this research highlights the need for pipeline operators to establish controls on the algorithms adopted by commercial NDT vendors.

Effects of AP and AP-ethyl on the properties of PA6

2017 ◽  
Vol 31 (12) ◽  
pp. 1609-1618
Author(s):  
Long Lijuan ◽  
He Wentao ◽  
Li Juan ◽  
Xiang Yushu ◽  
Qin Shuhao ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Fracture Surface ◽  
Thermal Degradation ◽  
Flame Retardant ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Cone Calorimeter Test ◽  
Mean Size ◽  
The Mean

In this work, the effects of inorganic phosphinate flame retardant of aluminum hypophosphite (AP) and organic phosphinate flame retardant of ethyl substituted phosphinates (AP-ethyl) on the thermal degradation, flame performance, and mechanical properties of polyamide 6 (PA6) were investigated. Scanning electron micrograph showed AP with the shape of bulk and the mean size of 8 μm while AP-ethyl with irregular shape and the mean size of 30 μm. Thermal analysis indicated that the thermal degradation behavior of flame-retardant PA6 was different from pure PA6. Moreover, the cone calorimeter test results revealed that peak heat release rate (PHRR) of PA6/AP (85/15) and PA6/AP-ethyl (85/15) decreased by 51% and 64%, respectively, compared with pure PA6. Furthermore, pure PA6 showed ductile stress–strain curve with the tensile strength of 54.8 MPa. However, PA6/AP and PA6/AP-ethyl displayed brittle stress–strain curve and their tensile strength decreased to 52.3 and 47.1 MPa, respectively. In addition, pure PA6 showed a glossy and tough fracture surface morphology. The rough fracture surface morphologies for PA6/AP and PA6/AP-ethyl were observed, and the interface of PA6/AP was more obscure than that of PA6/AP-ethyl. Consequently, the small particle size of AP had a more uniform dispersion in PA6 matrix.

Polysilicon Tensile Testing With Electrostatic Gripping

1998 ◽  
Vol 518 ◽  
Author(s):  
W. N. Sharpe ◽  
K. Turner ◽  
R. L. Edwards
Keyword(s):  
North Carolina ◽  
Young’S Modulus ◽  
Tensile Testing ◽  
Young's Modulus ◽  
Strain Curve ◽  
Electrostatic Forces ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Force Displacement

AbstractTechniques and procedures are described for tensile testing of polysilicon specimens that are 1.5 or 3.5 νm thick and have various widths and lengths. The specimens are fixed to the wafer at one end and have a large free end that can be gripped by electrostatic forces. This enables easy handling and testing and permits the deposition of 18 specimens on a one-centimeter square portion of a wafer. The displacement of the free end is monitored, which allows one to extract Young's modulus from the force-displacement record. Some of the wider specimens have two gold lines applied so that strain can be measured interferometrically directly on the specimen to record a stress-strain curve.The specimens were produced at the Microelectronics Center of North Carolina (MCNC). When compared with earlier results of wider MCNC specimens that were 3.5 μm thick, the Young's modulus is smaller and the strength is slightly larger.

Mechanical Characteristics of Inorganic Binder Stabilized Iron Tailings

2014 ◽  
Vol 508 ◽  
pp. 173-176
Author(s):  
Hong Bin Li ◽  
Fei Zhao ◽  
Bao Kuan Ning
Keyword(s):  
Clayey Soil ◽  
Soil Mechanics ◽  
Strain Curve ◽  
Confining Pressure ◽  
Material Strength ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Plastic Yield ◽  
Potential Safety ◽  
Huge Impact

As the largest solid waste in China, iron tailings have brought a huge impact and potential safety hazard to resources, environment and land. In this paper, using the stress-strain controlled soil mechanics tri-axial apparatus, the author researched the mechanics performance of the cement stabilized iron tailings in the laboratory. The result shows: Along with the increase of the cement dosage, stabilized material strength has improved significantly; Under the confining pressure from 300kPa to 500kPa, the increase of confining pressure is proportional to the strength of stabilized material. Moreover, lower cement content (3%-5%) of stabilized material, its stress-strain curve is similar to those of clayey soil, it has clear plastic yield characteristics; on the contrary, higher dosage of cement stabilized material (7%-9%), the plastic reduced and strength increased. Keywords: cement stabilized iron tailings; cement dosage; stress-strain curve; strength; confining pressure

The Stress-Strain Relationship in Ebonite

1934 ◽  
Vol 7 (1) ◽  
pp. 197-211
Author(s):  
B. L. Davies
Keyword(s):  
Tensile Strength ◽  
Plastic Flow ◽  
Testing Machine ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Tensile Testing Machine ◽  
Hooke’S Law ◽  
Hooke's Law ◽  
Soft Rubber

Abstract 1. A simple “extensometer” has been devised for the more accurate measurement of small elongations in hard rubber samples, thus enabling stress-strain curves to be obtained on a standard tensile testing machine. 2. The form of the curve has been described more fully than heretofore. It shows that hard rubber does not deform exactly in accordance with Hooke's Law, but exhibits plastic flow. 3. Deviations from Hooke's Law shown by the experimental curves depend upon the speed of stretching. Increased speed of elongation has been found to give higher readings of tensile strength. 4. Prolonged mastication of the rubber gives a weaker product, similar effects being obtainable by the use of a neutral softener. 5. The effects of increasing time of vulcanization have been described. The range of curves showing transition from over-cured soft rubber to ebonite indicates that the hard rubber curve is possibly related to the initial portion of the soft rubber curve. The plasticity of the overvulcanized rubber, as indicated by the deviation from Hooke's Law, increased with time of vulcanization until the “semi-ebonite” stage was reached. 6. The leather-like “semi-ebonites” differed from soft and hard rubber inasmuch as they were extremely sensitive to small changes in time of vulcanization, and inasmuch as their plasticity was such that the velocity of plastic flow was comparable with the rate of pulling (1 in. per minute), at a particular point in the test they experienced a large elongation at constant load, i. e., the velocity of flow was equal to the speed of pulling. Their plasticity decreased with further vulcanization. 7. The longest cures in the above-mentioned group gave products which were rigid at room temperature. Since these must be more resistant to shock than vulcanizates in a higher state of cure, it seems that the best technical cure of ebonite for mechanical purposes is that which gives maximum tensile strength combined with the property of undergoing considerable plastic flow (of the order of 5 per cent) at the constant maximum load, and at an arbitrarily fixed rate of stretching, the temperature being commensurate with the thermal conditions of service. Such a cure is clearly indicated by the stress-strain curve. 8. Accelerated ebonite mixings are more sensitive to time of cure than rubber-sulfur stocks without accelerators. An accelerator may produce very little effect on the tensile strength and breaking elongation, but may yield a stock which “scorches” readily. This prevulcanization was detrimental to the mechanical properties of the vulcanizate, even though it was so slight that its presence was not detected during normal processing. 9. Mineral rubber in ebonite stocks has been shown to accelerate the cure as indicated by the stress-strain curve. 10. Stocks containing high loadings of gas black gave vulcanizates which were weak and brittle. The effect of the black on the stiffness was similar to that produced by further cure. 11. The stress-strain curve provides a reliable means whereby stocks containing different accelerators and other compounding ingredients may be compared at equivalent states of vulcanization.

Ultra-Speed Tensile of Rubber and Synthetic Elastomers

1951 ◽  
Vol 24 (1) ◽  
pp. 144-160
Author(s):  
D. S. Villars
Keyword(s):  
Tensile Strength ◽  
High Speed ◽  
Relaxation Times ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Elongation At Break ◽  
Different Types ◽  
Speed Up ◽  
Pass Through

Abstract A high speed stress-strain machine has been developed which is capable of recording the stress-strain curve of elastomers at elongation rates up to 270 per cent/msec. Data are reported on two series of gum and tread stocks of Hevea and of the synthetic elastomers, GR-S, Hycar-OR, Butyl, Perbunan, and Neoprene-GN. The second (elastomer) series was also run at 150° C. In general, stress-strain curves fall into two classes. Stocks of elastomers which are known to crystallize on stretching tend to show tensile strengths which decrease with increasing speed up to about 10 per cent/msec, pass through a minimum, and rise more or less drastically to values 100 per cent (or more) greater than the Scott tensile strength. Elastomers which do not crystallize on stretching tend to show a steady rise in tensile strength with increasing speed. Elongation at break curves show a maximum with crystallizing stocks and no maximum with noncrystallizing stocks. The shape of the modulus vs. speed curves is accounted for on the hypothesis of different types of slipping bonds with different characteristic relaxation times. The shift of curves for tread stocks with temperature allows the estimation of a heat of activation of slippage. This comes out to be of the order of 3 kg.-cal.

The Effect of Solvents on the Stress-Strain Curve of Vulcanized Rubber

1930 ◽  
Vol 3 (1) ◽  
pp. 19-21 ◽  
Author(s):  
H. A. Tiltman ◽  
B. D. Porritt
Keyword(s):  
Tensile Strength ◽  
Marked Effect ◽  
Strain Curve ◽  
Theoretical Interest ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Cohesive Forces ◽  
Effect Of Solvents ◽  
Vulcanized Rubber ◽  
Permanent Effect

Abstract (1) The results indicate that the rigidity of a piece of vulcanized rubber is considerably reduced by the absorption of small amounts of a solvent; thus, at a strain of 6 ( = 600 per cent elongation) the absorption of 5 per cent by weight ( = 8 per cent by volume) of benzene lowers the rigidity by 21 per cent. (2) The greatest effect is produced by the first 20 or 30 per cent (by weight) of absorbed benzene, further absorption having a less marked effect on the stress-strain curve. (3) The absorption of solvent seems to have very little effect on the breaking elongation, although the tensile strength is considerably lowered. This conclusion, however, is probably no longer true in the case of rubber swollen by immersion in liquid, where the absorption is very much greater than in the present tests. (4) Absorption of solvent followed by complete drying appears to produce a slight, but technically negligible, permanent effect on the stress-strain curve. It is evident from these results that when it is necessary to use solvents, either in the process of manufacture or the after-treatment of rubber products, these should be selected as free as possible from high-boiling constituents liable to be permanently retained by the rubber with consequent detriment to its strength. A conclusion of some theoretical interest is that since all the stresses in the present investigation were calculated on the dimensions of the original dry rubber, the low rigidity of swollen rubber cannot be ascribed simply to the “dilution” of the rubber by the absorbed liquid, but must be due to a loosening of the cohesive forces between the ultimate particles of the material.

Rationalizing Sampling of Pipe Material Properties for Probabilistic Pipe Fracture Analyses

2016 ◽  
Author(s):  
Richard Olson ◽  
Bruce Young
Keyword(s):  
Material Properties ◽  
Crack Opening ◽  
Strain Curve ◽  
Initiation Toughness ◽  
Pipe Material ◽  
Stress Strain Curve ◽  
Opening Displacement ◽  
Time Step ◽  
Stress Strain ◽  
Suggested Approach

One element of probabilistic pipe fracture analyses is an assessment of the stability of cracks under applied load. If the load at some time step is greater than the cracked section can sustain, the state of the pipe is reported as ruptured. Another element of probabilistic pipe fracture analyses is the calculation of the crack opening displacement (COD) value which is used as an input to a leak rate calculation. Both of these analyses typically require pipe material properties that are sampled from a probabilistic distribution characterized by a mean value and some variance about the mean. Such properties include yield strength, ultimate strength, Ramberg-Osgood stress-strain curve coefficients, and fracture toughness curve parameters such as initiation toughness and tearing parameters. From a procedural perspective, it is tempting to sample all of the relevant parameters independently. However, in some instances, the assumption of independence leads to nonsensical conditions such as yield being greater than ultimate; yield and ultimate being completely disconnected from the underlying Ramberg-Osgood description of the stress-strain curve; J-R toughness curves that are convex instead of concave; or initiation J values as low as zero. This paper provides a suggested approach to sampling material properties for probabilistic pipe fracture analyses. The approach maintains consistency between yield, ultimate and the underlying Ramberg-Osgood stress-strain curve, and sets reasonable cutoff limits on the properties that are sampled. Equations for ensuring consistency among the related parameters are given along with justifications for the sampling limits, and an example of application of the proposed methodology.

Determination of Stress-Strain Curve for Microelectronic Solder Joint by ESPI Measurement and FE Analysis

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1983-1988
Author(s):  
Baik Woo Lee ◽  
Jeung Hyun Jeong ◽  
Woosoon Jang ◽  
Ju Young Kim ◽  
Dong Won Kim ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Thermal Deformation ◽  
Flip Chip ◽  
Computational Analysis ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Element Analysis

Many thermomechanical reliability studies on microelectronics and microsystems have relied upon computational analysis, since experimental work is rather difficult and very time-consuming. For computational analysis, it is essential to use as input accurate material properties; if not, the results of a reliability analysis may be very inaccurate. However, it is still quite difficult to arrive at unified material properties for modeling microelectronic assemblies because of the absence of standards for micro-material characterization, the difference between bulk and in-situ material properties, and so forth. The goal of this study was to determine the uniaxial stress-strain curve of a solder in a flip-chip assembly, using experimental measurements and finite-element analysis (FEA) of the solder's thermal deformation characteristics with increasing temperature. The thermal deformation of flip-chip solder joints was measured by electronic speckle pattern interferometry (ESPI). For the scale of evaluation required, the measurement magnification was modified to allow its application to micromaterials by using a long-working-distance microscope, iris and zoom lens. Local deformation of solder balls could be measured at submicrometer scale, and stress-strain curves could be determined using the measured thermal deformation as input data for finite-element analysis. The procedure was applied to an Sn-36Pb-2Ag flip-chip solder joint.

scholarly journals Analysis of High Strength Concrete processed from Recycled Concrete Aggregates

2021 ◽  
Vol 9 (12) ◽  
pp. 1757-1763
Author(s):  
Shanu Sharma
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Coarse Aggregate ◽  
Strain Curve ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Hardened Concrete ◽  
Stress Strain Curve ◽  
Stress Strain

Abstract: As everyone is aware of the fact that Natural Coarse Aggregate (NCA) is the main constituent of traditional concrete mixes. Whenever an existing concrete structure is demolished, it produces smashed concrete waste in the large amount. Concrete waste give rise to negative effects on the environment. To evade the environmental pollution and mark effective reuse of the concrete waste as Recycled Aggregates in the place of NCA. This operative initiative provides an opportunity to reduce air pollution and soil exploitation to some extent. Such concrete is sustainable in nature and also eco-friendly to the environment. Also, such waste material will lower the usage of naturally occurring stone to produce NCA and thus various natural energy resources will be safeguarded. This study covers the suitability norms for a material to be used for Recycled Aggregate. In this study the natural aggregate is replaced with recycled aggregate in the different percentages (0%, 25%, 50%). When percentage of recycled aggregate mixed in the fixed proportion as percentage replacement to natural aggregates, it imparts improvement in the property of fresh as well as hardened concrete like, compressive strength & split tensile strength. Laboratory results of this research indicates that the value of compressive strength, tensile strength stress-strain curve & NDT of these mixes drives on decreasing, but at the 25% replacement level, it achieves target mean strength. Hence, for the fundamental concrete mix Natural Coarse Aggregate can be efficiently replaced by the Recycled Aggregate to the range of 25%. Keywords: Concrete, Recycled aggregate, Natural Coarse Aggregate (NCA), Compressive Strength, Tensile strength, , NDT, Stress-Strain Curve

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