Recovering Lead in Rubber Factory

1930 ◽  
Vol 3 (3) ◽  
pp. 470-471
Author(s):  
F. L. Haushalter
Keyword(s):  
Tensile Strength ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Percentage Elongation ◽  
Pure Lead ◽  
Straight Line ◽  
Lead Melts ◽  
Rate Of Cooling ◽  
Set Up ◽  
Vulcanization Process

Abstract When we say that lead melts at 621 ° F. and has a tensile strength of 1900 lb. per sq. in., we have in mind pure lead that has not been remelted many times in crucibles that are not always clean. This metal, too, as ordinarily used in pipes and conduits has been drawn; stresses have been set up in the lead by this process, and their magnitude depends upon several factors, such as temperature of extrusion, extent of oxidation, rate of cooling, and impurities accumulated in the remelting. Where lead is melted and extruded onto wire and hose the tensi1e strength of such lead, when removed from the wire or hose, has increased to about 2400 lb. per sq. in. The percentage elongation, however, has decreased from about 50 to about 25. Industries where lead is used again and again by remelting, as in the rubber industry, where hose is vulcanized in a lead casing, the casing removed after vulcanization of the hose and remelted, the problem of controlling the physical properties of the lead becomes a serious one. After pure lead has been extruded onto the hose and the tensile strength thereby stepped up to about 2400 lb. per sq. in., the tensile strength then falls appreciably below the original value of 1900 lb. per sq. in. as soon as the vulcanization process begins, with the temperature of vulcanization at 280° F. When the samples of lead as stripped from the hose after vulcanization were tested for tensile strength at various temperatures, the curve approximated a straight line. A stress-strain curve on the lead at a temperature of 280?? F. indicates that at a tensile stress of about 600 lb. per sq. in. the lead begins to yield, for the curve departs from the original slope.

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.

Direct Tensile Strength Measurement of Concrete

2011 ◽  
Vol 117-119 ◽  
pp. 9-14 ◽  
Author(s):  
Mohammad Iqbal Khan
Keyword(s):  
Tensile Strength ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Strength Measurement ◽  
Ongoing Research ◽  
Tensile Strength Test ◽  
Direct Tensile ◽  
Indirect Tests ◽  
Direct Tensile Strength

The evaluation of the tensile strength and determination of the tensile stress-strain curve using indirect tests becomes approximate hence there is a necessity for exploring direct tensile strength measurement. This investigation is part of ongoing research on the development of direct tensile strength measurement. In this paper direct tensile strength test has been proposed and the results obtained have been compared with compressive strength and flexural strength. It has been found that results obtained are well comparable and relationships are similar to that proposed in earlier findings.

The Effect of Strain Hardening in an Annular Slab

1953 ◽  
Vol 20 (4) ◽  
pp. 530-536
Author(s):  
P. G. Hodge
Keyword(s):  
Strain Hardening ◽  
Biaxial Tension ◽  
Complete Solution ◽  
Maximum Shear Stress ◽  
Strain Curve ◽  
Linear Strain ◽  
Stress Strain Curve ◽  
Line Segments ◽  
Straight Line ◽  
Strain Components

Abstract A procedure is outlined for obtaining the stresses and strains in a circular slab with a cutout, subject to uniform biaxial tension. An arbitrary stress-strain curve in tension is approximated by any number of straight-line segments. For biaxial states of stress the material is assumed to satisfy a flow law based on the maximum shear stress, and to be incompressible throughout. The general equations are given and then simplified by assuming that boundary motions may be neglected if the strains are small, and that elastic strain components may be neglected if the strains are large. For the case of linear strain hardening a complete solution is given in closed form. If the rate of strain hardening is small, these results may be simplified further.

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.

Large deformation of time-dependent materials in uniaxial tension

1969 ◽  
Vol 4 (3) ◽  
pp. 199-207
Author(s):  
P D W Soden ◽  
R Sowerby
Keyword(s):  
Tensile Stress ◽  
Strain Curve ◽  
Tensile Tests ◽  
Cellulose Nitrate ◽  
Time Dependent ◽  
Extension Rate ◽  
Creep Data ◽  
Stress Strain Curve ◽  
Pure Lead ◽  
Commercially Pure

Unaxial tensile tests have been conducted on commercially pure lead and cellulose nitrate, both time-dependent materials. It is shown that it is possible to predict all the important features of a tensile stress-strain curve from creep-test data, including the dependence of the curve upon extension rate. The behaviour of cellulose nitrate at the yield point is shown to be similar in nature to that of lead at the ultimate point. The stresses at these particular points were predicted with remarkable accuracy from the creep data over a range of extension rates from 1 per cent per minute up to 100 per cent per minute.

scholarly journals Torsional hysteresis of mild steel

1917 ◽  
Vol 93 (651) ◽  
pp. 313-332 ◽  
Keyword(s):  
Mild Steel ◽  
Yield Point ◽  
Elastic Limit ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Straight Line ◽  
Straight Portion ◽  
Strain Axis ◽  
Inferior Limit

The stress-strain curve from no load to fracture for mild steel as usually obtained consists of three parts: (1) A straight line, followed by a part deviating only slightly from this straight portion; (2) a sharp bend, followed by a part approximately parallel to the strain axis; and (3) a curved rising part, leading ultimately to the breaking point. It is generally assumed that Hooke’s Law holds throughout the part (1), and is immediately followed by the sharply defined bend which constitutes the yield point. For mild steel first stressed in tension and then in compression, or subjected to positive and then negative torsional stresses, the stress-strain curve within a considerable range of stress is also supposed to be a straight line. It is further well known that if mild steel is stressed in tension beyond the yield point the elastic limit is raised, but only at the expense of lowering it in compression; or, if it is twisted beyond the yield point in one direction, its elastic limit is raised for stresses in that direction, but lowered for those in the opposite direction. Attempts have been made to relate the range of stress through which the stress-strain curve is a straight line with that through which a material, such as mild steel, can be stressed an infinite number of times without fracture. This is expressed by the well known Bauschinger’s Law, which, as stated by Mr. Leonard Bairstow, is as follows:—“The superior limit of elasticity can be raised or lowered by cyclical variations of stress, and at the inferior limit of elasticity will be raised or lowered by a definite, but not necessarily the same, amount. The range of stress between the two elastic limits has therefore a value which depends only on the material and the stress at the inferior limit of elasticity. This elastic range of stress is the same in magnitude as the maximum range of stress, which can be repeatedly applied to a bar without causing fracture, no matter how great the number of repetitions.”

scholarly journals I. On the recovery of iron from overstrain

1900 ◽  
Vol 193 ◽  
pp. 1-46 ◽  
Keyword(s):  
Applied Load ◽  
Elastic Limit ◽  
Strain Curve ◽  
Plastic State ◽  
Stress Strain Curve ◽  
Permanent Set ◽  
Straight Line ◽  
Small Load ◽  
Primitive Condition ◽  
Primitive State

It has long been known that iron which has been overstrained in tension—that is to say strained beyond the yield-point so that it suffers a permanent stretch—possesses very different elastic properties from the same iron in its primitive condition. The material is said to be “ hardened ” by stretching,* since the ultimate effect of such treatment is to raise the elastic limit and reduce the ductility of the material. More recently, attention has been called to the fact that, primarily, the result of tensile overstrain is to make iron assume a semi-plastic state, so that the elastic limit, instead of being raised by stretching, is first of all lowered, it may be to zero. This plasticity may be shown by applying a comparatively small load to a bar of iron or steel which has just been overstrained by the application and removal of a large stretching load. When the small load is put on, the bar will be found to elongate further than it would had the material been in its primitive state ; and a slight continued elongation—a “ creeping ”—may occur after the small load has been applied. If this load be withdrawn, a quite appreciable permanent, or semi-permanent, set will be found to have been produced ; a set which diminishes slightly, and, if small, may vanish, provided time be allowed for backward creeping to take effect. It may also be shown that, if the re-applied load be increased, the elongation produced will increase in a greater proportion. Thus, if a stress-strain curve be obtained from a recently overstrained bar of iron or steel, it will show, even for small loads, a marked falling away from the straight line which would indicate obedience to Hooke’s law.

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.

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.

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