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NASATM-2000-210098 Fatigue Crack Growth Rate Test Results for Al-Li 2195 Parent Metal, Vari

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NASA/TM-2000-210098Fatigue Crack Growth Rate Test Results for Al-Li 2195 Parent Metal, Variable Polarity Plasma Arc Welds and Friction Stir WeldsRobert A. Hafley, John A. Wagner, and Marcia S. DomackLangley Research Center, Hampton, VirginiaMay 2000The NASA STI Program Office ... in ProfileSince its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) Program Office plays a key part in helping NASA maintain this important role.The NASA STI Program Office is operated by Langley Research Center, the lead center for NASAÕs scientific and technical information. The NASA STI Program Office provides access to the NASA STI Database, the largest collection of aeronautical and space science STI in the world. The Program Office is also NASAÕs institutional mechanism for disseminating the results of its research and development activities. 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English-language translations of foreignscientific and technical materialpertinent to NASAÕs mission.Specialized services that complement the STI Program OfficeÕs diverse offerings include creating custom thesauri, building customized databases, organizing and publishing research results ... even providing videos.For more information about the NASA STI Program Office, see the following:·Access the NASA STI Program Home Page at ·E-mail your question via the Internet to help@·Fax your question to the NASA STIHelp Desk at (301) 621-0134·Phone the NASA STI Help Desk at(301) 621-0390·Write to:NASA STI Help DeskNASA Center for AeroSpace Information 7121 Standard DriveHanover, MD 21076-1320National Aeronautics and Space Administration Langley Research CenterHampton, Virginia 23681-2199May 2000NASA/TM-2000-210098Fatigue Crack Growth Rate Test Results for Al-Li 2195 Parent Metal, Variable Polarity Plasma Arc Welds and Friction Stir WeldsRobert A. Hafley, John A. Wagner, and Marcia S. Domack Langley Research Center, Hampton, VirginiaAvailable from:NASA Center for AeroSpace Information (CASI)National Technical Information Service (NTIS)7121 Standard Drive5285 Port Royal RoadHanover, MD 21076-1320Springfield, VA 22161-2171(301) 621-0390(703) 605-6000AcknowledgmentsThis work was conducted under Space Act Agreement 298, funded by Lockheed-Martin Michoud Space Systems. The authors would like to acknowledge the contributions of Paula Hartley and William Arbegast of Lockheed-Martin Michoud Space Systems.The use of trademarks or names of manufacturers in this report is for accurate reporting and does not constitute an official endorsement, either expressed or implied, of such products or manufacturers by the National Aeronautics and Space Administration.CONTENTS CONTENTS (iii)LIST OF FIGURES (iv)LIST OF TABLES (v)Abstract (1)1. Introduction (1)2. Symbols and Abbreviations (1)3. Materials, Specimen and Test Hardware (2)4. Test Procedure (2)5. Results (2)5.1 Plate (2)5.2 Variable Polarity Plasma Arc Welds (2)5.3 Friction Stir Welds (3)6. Discussion (3)7. Conclusions (4)8. References (4)Figure 1.C(T) Specimen Design (5)Figure 2.Effect of Temperature on the Fatigue Crack Growth Rate in 0.25 in. AL-Li 2195-T8 Plate in the L-T Orientation (7)Figure 3.Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.25 in. AL-Li 2195-T8 Plate in the T-L Orientation (9)Figure 4.Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the L-T Orientation (11)Figure 5.Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the T-L Orientation (13)Figure 6.Effect of Temperature on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the L-T Orientation (15)Figure 7.Effect of Temperature on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the T-L Orientation (17)Figure 8.Effect of Thickness on the Fatigue Crack Growth Rate in AL-Li 2195-T8 Plate in the L-T Orientation (19)Figure 9.Effect of Thickness on the Fatigue Crack Growth Rate in AL-Li 2195-T8 Plate in the T-L Orientation (21)Figure 10.Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.25 in AL-Li 2195-T8 Variable Polarity Plasma Arc Welds in the L-T Orientation (23)Figure 11.Fatigue Crack Growth Rate in 0.25 in. Al-Li 2195-T8 Friction Stir Welds in the L-T Orientation at Ambient Temperature (25)Figure 12.Fatigue Crack Growth Rate in 0.25 in. Al-Li 2195-T8 Friction Stir Welds in the L-T Orientation at Cryogenic Temperature (27)Figure 13.Fatigue Crack Growth Rate in 0.50 in. Al-Li 2195-T8 Friction Stir Welds in the L-T Orientation at Elevated Temperature (29)Figure 14.Fatigue Crack Growth Rate in 0.50 in. Al-Li 2195-T8 Friction Stir Welds in the L-T Orientation at Ambient Temperature (31)Figure 15.Fatigue Crack Growth Rate in 0.50 in. Al-Li 2195-T8 Friction Stir Welds in the L-T Orientation at Cryogenic Temperature (33)Table 1.Typical Mechanical Properties for Al 2195-T8 Plate and Weldments (3)Table 2.Effect of Temperature on the Fatigue Crack Growth Rate in 0.25 in. AL-Li 2195-T8 Plate in the L-T Orientation (6)Table 3.Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.25 in. AL-Li 2195-T8 Plate in the T-L Orientation (8)Table 4.Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the L-T Orientation (10)Table 5.Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the T-L Orientation (12)Table 6.Effect of Temperature on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the L-T Orientation (14)Table 7.Effect of Temperature on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the T-L Orientation (16)Table 8.Effect of Thickness on the Fatigue Crack Growth Rate in AL-Li 2195-T8 Plate in the L-T Orientation (18)Table 9.Effect of Thickness on the Fatigue Crack Growth Rate in AL-Li 2195-T8 Plate in the T-L Orientation (20)Table 10.Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.25 in AL-Li 2195-T8 Variable Polarity Plasma Arc Welds in the L-T Orientation (22)Table 11.Fatigue Crack Growth Rate in 0.25 in. Al-Li 2195-T8 Friction Stir Welds in the L-T Orientation at Ambient Temperature (24)Table 12.Fatigue Crack Growth Rate in 0.25 in. Al-Li 2195-T8 Friction Stir Welds in the L-T Orientation at Cryogenic Temperature (26)Table 13.Fatigue Crack Growth Rate in 0.50 in. Al-Li 2195-T8 Friction Stir Welds in the L-T Orientation at Elevated Temperature (28)Table 14.Fatigue Crack Growth Rate in 0.50 in. Al-Li 2195-T8 Friction Stir Welds in the L-T Orientation at Ambient Temperature (30)Table 15.Fatigue Crack Growth Rate in 0.50 in. Al-Li 2195-T8 Friction Stir Welds in the L-T Orientation at Cryogenic Temperature (32)Table 16.Fatigue Crack Growth Rate, da/dN (10-6 in/cycle), for Al-Li 2195-T8 Plate andWeldments (34)Table 17.Summary of Fatigue Crack Growth Rate, da/dN (10-6 in/cycle), for Al-Li 2195-T8 Plate and Weldments (35)AbstractThe fatigue crack growth rate of aluminum-lithium (Al-Li) alloy 2195 plate and weldments was determined at 200°F, ambient temperature and –320°F. The effects of stress ratio (R), welding process, orientation and thickness were studied. Results are compared with plate data from the Space Shuttle Super Lightweight Tank (SLWT) allowables program. Data from the current series of tests, both plate and weldment, falls within the range of data generated during the SLWT allowables program.1. IntroductionThe application of advanced aluminum alloys to Reusable Launch Vehicle (RLV) structures required the characterization of the time dependent properties of candidate alloys. The candidate alloy studied in this investigation was aluminum-lithium (Al-Li) alloy 2195. Prior to this investigation, the database which existed for 2195 included strength and fracture data primarily developed for expendable launch vehicle applications. The application of 2195 in RLV systems required the full characterization of the fatigue crack growth rate behavior of both parent and welded 2195 at service temperatures. The thermal profile for RLV structures included ambient temperature, as well as elevated temperatures during ascent and descent, and cryogenic temperatures for oxidizer storage.2. Symbols and Abbreviationsa crack lengthAl-Li aluminum-lithiumASTM American Society for Testing and MaterialsC normalized K-gradientC(T)compact specimenda/dN fatigue crack growth rate∆K stress-intensity factor rangeFCGR fatigue crack growth rateFSW friction stir weldingFtu ultimate tensile strengthFty 0.2% offset yield strengthHT heat treatmentK stress-intensity factorKmax maximum stress-intensity factorKmin minimum stress-intensity factorL direction parallel to rolling directionL-T denotes fracture plane normal to L with propagation in T directionLN2liquid nitrogenR stress ratioRLV Reusable Launch VehicleSLWT Super Lightweight Tankt thicknessT direction perpendicular to rolling directionT-L denotes fracture plane normal to T with propagation in L direction VPPAW variable polarity plasma arc weldingW specimen width3. Materials, Specimen and Test HardwareFatigue crack growth rate (FCGR) tests were conducted on aluminum-lithium (Al-Li) alloy 2195-T8 plate and weldments. Two gages of plate, 0.25 in. and 0.50 in., were tested in two orientations, L-T and T-L, at 200°F and ambient temperature (~75°F). Weldments of the same gages, prepared by variable polarity plasma arc welding (VPPAW) using Al 4043 filler metal or friction stir welding (FSW), were also tested at 200°F, ambient temperature (~75°F) and/or -320°F.Compact (C(T)) specimens, Fig.1, were tested per ASTM E647-95a (ref. 1). Plate specimen thickness was the nominal material thickness. Weldment specimen thicknesses were reduced the minimum amount required to ensure that specimen faces were flat and parallel. The machined notch on the weldments was located along the weld centerline. Clevises with flat bottom holes were fabricated per Fig A2.3 in ref. 1. Elevated temperature tests were conducted in an environmental chamber, while specimens were immersed in liquid nitrogen (LN) during cryogenic tests.24. Test ProcedureTests were conducted in servohydraulic test frames controlled by an automated fatigue crack growth test system. A constant stress ratio, R, of 0.1 or 0.5 was used in all tests. Specimens were fatigue precracked at ∆K=10 ksi√in from a/W=0.2 to a/W=0.3. A K-decreasing test was conducted over the range of ∆K=10 ksi√in to 5 ksi√in in order to obtain near-threshold crack growth rates. Tests were conducted using a constant K-gradient, C, of -2 in order to eliminate effects of prior loading on the K-decreasing portion of the test. A K-increasing test was then conducted from a ∆K=5 ksi√in until instrumentation ranges were exceeded. At the conclusion of the tests, the specimens were fractured to permit examination of the fracture surface and measurement of the final crack length. Data analysis was conducted in compliance with ref.1.5. ResultsTypical mechanical properties for Al2195-T8 plate and weldments are presented in Table 1(ref. 2, plate and private communication, weldments). FCGR results are presented in Tables 2-15 and Figures 2-15, are summarized in Table 16 at selected levels of stress intensity and compared with data from the Space Shuttle Super Lightweight Tank (SLWT) design allowables program (ref. 2) in Table 17.5.1 PlateTwo thicknesses of 2195 plate, 0.25 in. and 0.50 in., were tested in two orientations, L-T and T-L, at two temperatures, 200°F and 75°F, and two stress ratios, R=0.1 and 0.5. Results of the FCGR tests illustrating the effects of temperature are presented in Table 2 and Figure 2 for 0.25 in. plate and Tables 6-7 and Figures 6-7 for 0.50 in. plate. The effect of stress ratio on the FCGR is shown in Table 3 and Figure 3 for 0.25in. plate and in Tables 4-5 and Figures 4-5 for 0.5 in. plate. The effect of thickness on the FCGR in 2195 plate is illustrated in Tables 8-9 and Figures 8-9. There appears to be little effect of orientation, thickness or test temperature on the FCGR, however increasing the stress ratio from 0.1 to 0.5 does increase the FCGR.5.2 Variable Polarity Plasma Arc WeldsVariable polarity plasma arc welds of 0.25 in. plate were tested at 75°F with R=0.1 and 0.5. Results of the FCGR tests are presented in Table 10 and Figure 10. There was a significant effect of R on FCGR. At R=0.1, crack growth data could not be generated at or below ∆K=10 ksi√in, presumably due toresidual stresses. Data was obtained at ∆K=10 ksi √in and an R of 0.5. At ∆K=20 ksi √in, the FCGR at R=0.5 is two orders of magnitude higher than at R=0.1.Table 1. Typical Mechanical Properties for Al 2195-T8 Plate and WeldmentsPlate1VPPAW2FSW2Temp., °FProp.Orient.0.25 in.0.5 in.0.25 in.0.25 in.0.5 in.L 6666———Fty, ksiT 6262———L 6868—53—200Ftu, ksi T 6565———L 8485—3935Fty, ksiT 8080———L 898952605775Ftu, ksi T 8686———L 9694———Fty, ksiT 9291———L 108107—75—-320Ftu, ksiT102104———1. Ref. 22. Private communication5.3 Friction Stir WeldsFriction stir welds of 0.25 in and 0.50 in plate were tested at 200°F, 75°F and/or -320°F at R=0.5.Results of the FCGR tests at ambient temperature are presented in Table 11 and Figure 11 for 0.25 in.welds and Table 14 and Figure 14 for 0.5 in. welds; cryogenic temperature results are presented in Table 12 and Figure 12 for 0.25 in. welds and Table 15 and Figure 15 for 0.5 in. welds; elevated temperature results are presented in Table 13 and Figure 13 for 0.5 in. welds. There does not appear to be any effect of thickness on the FCGR of Friction Stir Welds. However, the FCGR increases for tests conducted at 200°F and -320°F, compared to tests conducted at 75°F.6. DiscussionThe FCGR of Al-Li 2195-T8 plate and weldments at three selected levels of ∆K, 6, 10 and 20ksi √in, for each specimen tested is shown in Table 16. Results from replicate specimens of 2195-T8 plate show excellent agreement. Tests conducted on weldments exhibit more scatter, possibly due to residual stress effects from the welding process.The FCGR of the VPPAW material at a stress ratio of 0.1 is significantly lower than that of the Al-Li 2195-T8 plate at a comparable stress intensity. At a stress ratio of 0.5 and a stress intensity of 10 ksi √in,the FCGR of the VPPAW material is lower than that of the Al-Li 2195-T8 plate. However, at a stress ratio of 0.5 and a stress intensity of 20 ksi √in the FCGR of the VPPAW material is significantly higher than that of the Al-Li 2195-T8 plate. The FCGR of the FSW material is slightly higher than that of Al-Li 2195-T8 plate at similar stress ratios and stress intensities. This may be attributable to the low residual stress due to welding. These differences in rates for VPPAW material and FSW material as compared to plate may reflect differences in the level of residual stresses resulting from the two welding processes.The results of this study are summarized in Table 17, along with data from the SLWT designallowables program. All data generated in this program falls to the low end of the broad range of room temperature FCGR data from the SLWT design allowables program. The broad range of data from theSLWT design allowables can be accounted for by the different material thicknesses tested, 0.25 in. and 1.5 in., the inclusion of short transverse test specimen orientations, S-T and T-S, and testing several different production lots of material.7. ConclusionsThe FCGR of FSW Al-Li 2195-T8 plate is similar to that of unwelded Al-Li 2195-T8 plate at similar stress intensities and stress ratios.The FCGR of VPPAW Al-Li 2195-T8 plate is lower than that of unwelded Al-Li 2195-T8 plate at similar stress ratios and stress intensities below 10 ksi√in. At stress intensities above 10 ksi√in, the FCGR of VPPAW Al-Li 2195-T8 plate is higher than that of unwelded Al-Li 2195-T8 plate.8. References1.Standard Test Method for Measurement of Fatigue Crack Growth Rates. ASTM Designation: E 647-95a, Volume 03.01 of the 1997 Annual Book of ASTM Standards, 1997, pp. 557-593.2.Reinmuller, R. E., SO 89818 Al-Li Materials Database, Lockheed Martin Manned Space Systems,New Orleans, LA 70189.Figure 1. C(T) Specimen Design2 HOLES 1.000 Dia.+0.002-0.0000.800±0.0204.00±0.0205.00±0.040t1.100±0.0201.100±0.0202.40±0.0202.40±0.020-A--A--A--A-60°NOTES:1) ALL DIMENSIONS IN INCHES2) -A- SURFACES SHALL BE PERPENDICULAR AND PARALLEL WITHIN 0.008 AS APPLICABLE 3) THE SPECIMEN CENTERLINE SHALL BE ON THE WELD CENTERLINE WITHIN 0.0204) WELD BEAD REINFORCEMENT SHALL BE REMOVED FLUSH WITH SPECIMEN SURFACE 5) SPECIMEN THICKNESS MAY BE REDUCED TO ENSURE COMPLIANCE WITH NOTES 2 AND 46) THE INTERSECTION OF THE MACHINED NOTCH SHALL BE ON THE SPECIMEN CENTERLINE WITHIN 0.0207) SURFACE FINISH 32 µINCHES RMS OR BETTER16164” weld da/dN spec.XXXXXXXSPECIMEN IDXXXXXXXSPECIMEN IDDETAIL OF INTEGRAL KNIFE EDGE0.1500.0900.05060°90°C L0.0450.075Fatigue Crack Growth Rates at Defined Levels of Stress Intensity Factor Taken From K-Increasing Curve Data Associated with Figure 2 Indicating Effect of TemperatureMaterial: Aluminum 2195Condition: T8Environment: Lab AirStress Ratio (R): 0.1∆K da/dN (10-6 in/cycle)(ksi√in)(a)(c)(d)P25LT1P25LT2P25LT375°F200°F200°F5.150.24∆Kmin 5.160.245.150.236.000.420.430.467.00 1.09 1.20 1.458.00 2.10 2.24 2.599.00 2.57 3.59 4.3110.00 3.91 5.33 5.9411.00 5.867.008.0412.007.689.0210.5013.0010.1911.3313.1914.0012.0513.6315.5615.0014.2215.4718.5316.0016.8717.9521.5517.0020.3819.8219.8218.0022.9122.5027.6419.0026.5424.8931.7720.0030.7028.2035.00 24.0745.13∆Kmax 24.0940.3424.0852.01CONDITION/HT: T8FORM: 0.25 in. thick plate STRESS RATIO (R): 0.1SPECIMEN TYPE: C(T)SPECIMEN THICKNESS: 0.285-0.286 in.ORIENTATION: L-T SPECIMEN WIDTH: 4.002-4.003 in.FREQUENCY; 15 HZ ENVIRONMENT: Lab Air∆K, ksi √in 110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(a)C=-2C=+2P25LT1, 75°F∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(c)C=-2C=+2P25LT2, 200°F∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(d)C=-2C=+2P25LT3, 200°FTable 3. Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.25 in. AL-Li 2195-T8 Plate in the T-L OrientationFatigue Crack Growth Rates at Defined Levels of Stress Intensity Factor Taken From K-Increasing Curve Data Associated with Figure 3 Indicating Effect of Stress RatioMaterial: Aluminum 2195Condition: T8Environment: 200°F, Lab Air∆K da/dN (10-6 in/cycle)(ksi√in)(a)(b)(c)(d)P25TL5P25TL6P25TL7P25TL8R=0.1R=0.1R=0.5R=0.55.070.21∆Kmin 5.060.185.16 3.315.16 3.786.000.260.31 1.09 1.367.000.510.48 2.73 2.698.00 1.75 1.02 4.47 4.409.00 3.03 1.98 6.52 6.4810.00 4.51 2.8011.00 5.65 3.9712.007.63 5.2113.009.94 6.6714.0012.048.1815.0015.1110.3216.0017.0018.0019.0020.0015.9817.37∆Kmax 15.1410.669.998.959.417.36CONDITION/HT: T8FORM: 0.25 in. thick plate SPECIMEN TYPE: C(T)SPECIMEN THICKNESS: 0.270-0.271 in.ORIENTATION: T-L SPECIMEN WIDTH: 4.001 in.FREQUENCY; 15 HZENVIRONMENT: 200°F, Lab Air∆K, ksi √in 110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(a)C=-2C=+2P25TL5, R=0.1∆K, ksi √in 110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(b)C=-2C=+2P25TL6, R=0.1∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(c)C=-2C=+2P25TL7, R=0.5∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(d)C=-2C=+2P25TL8, R=0.5Fatigue Crack Growth Rates at Defined Levels of Stress Intensity Factor Taken From K-Increasing Curve Data Associated with Figure 4 Indicating Effect of Stress RatioMaterial: Aluminum 2195Condition: T8Environment: 200°F, Lab Air∆K da/dN (10-6 in/cycle)(ksi√in)(a)(b)(c)P50LT1P50LT2P50LT3R=0.1R=0.1R=0.55.480.24∆Kmin 5.160.165.160.276.000.330.250.787.000.620.41 2.168.00 1.82 1.10 3.629.00 3.21 2.21 5.5010.00 4.67 3.427.3011.00 6.41 5.059.7612.008.597.3012.0813.0010.558.6814.9114.0013.3810.9618.3615.0015.8313.3121.6516.0019.9217.5026.6517.0021.2319.5132.4318.0024.5322.2137.1019.0026.2724.5343.8820.0031.9526.7551.68 24.0544.25∆Kmax 27.7267.0521.8373.13CONDITION/HT: T8FORM: 0.50 in. thick plate SPECIMEN TYPE: C(T)SPECIMEN THICKNESS: 0.494-0.497 in.ORIENTATION: L-T SPECIMEN WIDTH: 3.999-4.003 in.FREQUENCY; 15 HZENVIRONMENT: 200°F, Lab Air∆K, ksi √in 110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(a)C=-2C=+2P50LT1, R=0.1∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(b)C=-2C=+2P50LT2, R=0.1∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(c)C=-2C=+2P50LT3, R=0.5Table 5. Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the T-L OrientationFatigue Crack Growth Rates at Defined Levels of Stress Intensity Factor Taken From K-Increasing Curve Data Associated with Figure 5 Indicating Effect of Stress RatioMaterial: Aluminum 2195Condition: T8Environment: 200°F, Lab Air∆K da/dN (10-6 in/cycle)(ksi√in)(a)(b)(c)P50TL1P50TL2P50TL3R=0.1R=0.1R=0.55.160.16∆Kmin 5.160.165.160.186.000.250.250.287.000.440.36 1.048.000.970.56 2.319.00 2.31 1.32 4.3210.00 3.79 2.42 6.3711.00 5.48 3.698.8212.007.42 5.6411.9713.009.637.7314.9214.0012.139.7918.5715.0015.5512.3824.3316.0019.8517.2136.5217.0020.8818.1035.9818.0025.8320.7846.8419.0030.2523.2058.6820.0033.5428.0670.30 26.5874.44∆Kmax 27.2565.9424.16216.99Figure 5. Effect of Stress Ratio on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the T-L OrientationCONDITION/HT: T8FORM: 0.50 in. thick plate SPECIMEN TYPE: C(T)SPECIMEN THICKNESS: 0.493-0.494 in.ORIENTATION: T-L SPECIMEN WIDTH: 3.999-4.003 in.FREQUENCY; 15 HZENVIRONMENT: 200°F, Lab Air∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(a)C=-2C=+2P50TL1, R=0.1∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(b)C=-2C=+2P50TL2, R=0.1∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(c)C=-2C=+2P50TL3, R=0.5Fatigue Crack Growth Rates at Defined Levels of Stress Intensity Factor Taken From K-Increasing Curve Data Associated with Figure 6 Indicating Effect of TemperatureMaterial: Aluminum 2195Condition: T8Environment: Lab AirStress Ratio (R): 0.5∆K da/dN (10-6 in/cycle)(ksi√in)(a)(b)P50LT3P50LT4200°F75°F∆Kmin 5.160.275.160.556.000.78 1.267.00 2.16 2.238.00 3.62 3.479.00 5.50 4.9210.007.30 6.7911.009.768.5312.0012.0810.7313.0014.9113.0114.0018.3616.3715.0021.6520.0416.0026.6524.5417.0032.4327.5718.0037.1033.5219.0043.8842.9520.0051.6855.74∆Kmax 21.8373.1324.65135.39CONDITION/HT: T8FORM: 0.50 in. thick plate STRESS RATIO (R): 0.5SPECIMEN TYPE: C(T)SPECIMEN THICKNESS: 0.497 in.ORIENTATION: L-T SPECIMEN WIDTH: 4.002-4.003 in.FREQUENCY; 15 HZ ENVIRONMENT: Lab Air∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(a)C=-2C=+2P50LT3, 200°F∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(b)C=-2C=+2P50LT4, 75°FTable 7. Effect of Temperature on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the T-L OrientationFatigue Crack Growth Rates at Defined Levels of Stress Intensity Factor Taken From K-Increasing Curve Data Associated with Figure 7 Indicating Effect of TemperatureMaterial: Aluminum 2195Condition: T8Environment: Lab AirStress Ratio (R): 0.5∆K da/dN (10-6 in/cycle)(ksi√in)(a)(b)P50TL3P50TL4200°F75°F∆Kmin 5.160.185.160.416.000.280.847.00 1.04 2.468.00 2.31 3.879.00 4.32 5.3010.00 6.377.0911.008.829.0012.0011.9711.7413.0014.9214.9014.0018.5719.0915.0024.3324.0716.0036.5230.5017.0035.9836.0618.0046.8442.9919.0058.6857.9720.0070.3071.04∆Kmax 24.16216.9924.19170.27Figure 7. Effect of Temperature on the Fatigue Crack Growth Rate in 0.50 in. AL-Li 2195-T8 Plate in the T-L Orientation CONDITION/HT: T8FORM: 0.50 in. thick plate STRESS RATIO (R): 0.5SPECIMEN TYPE: C(T)SPECIMEN THICKNESS: 0.494-0.498 in.ORIENTATION: T-L SPECIMEN WIDTH: 3.999-4.003 in.FREQUENCY; 15 HZ ENVIRONMENT: Lab Air∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(a)C=-2C=+2P50TL3, 200°F∆K, ksi √in110100d a /d N , i n /c y c l e10-810-710-610-510-410-310-210-1(b)C=-2C=+2P50TL4, 75°FFatigue Crack Growth Rates at Defined Levels of Stress Intensity Factor Taken From K-Increasing Curve Data Associated with Figure 8 Indicating Effect of ThicknessMaterial: Aluminum 2195Condition: T8Orientation: L-TEnvironment: 200°F, Lab AirStress Ratio (R): 0.1∆K da/dN (10-6 in/cycle)(ksi√in)(a)(b)(c)(d)P25LT2P25LT3P50LT1P50LT20.25 in.0.25 in.0.50 in.0.50 in.5.160.24∆Kmin 5.150.235.480.245.160.166.000.430.460.330.257.00 1.20 1.450.620.418.00 2.24 2.59 1.82 1.109.00 3.59 4.31 3.21 2.2110.00 5.33 5.94 4.67 3.4211.007.008.04 6.41 5.0512.009.0210.508.597.3013.0011.3313.1910.558.6814.0013.6315.5613.3810.9615.0015.4718.5315.8313.3116.0017.9521.5519.9217.5017.0019.8219.8221.2319.5118.0022.5027.6424.5322.2119.0024.8931.7726.2724.5320.0028.2035.0031.9526.75 24.0940.34∆Kmax 24.0852.0124.0544.2527.7267.05。

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西安2024年02版小学3年级第10次英语第四单元测验卷

西安2024年02版小学3年级第10次英语第四单元测验卷

西安2024年02版小学3年级英语第四单元测验卷考试时间：80分钟（总分:120）B卷考试人：_________题号一二三总分得分一、选择题(共计20题，共40分)1、Which planet is known as the "Blue Planet"?A. MarsB. NeptuneC. EarthD. Uranus2、What do you call a person who works on a farm?A. FarmerB. GardenerC. RancherD. All of the above3、What do we call the person who studies history?A. HistorianB. ScientistC. BiologistD. Chemist4、选择题：What is the name of the famous explorer who discovered America?A. Christopher ColumbusB. Ferdinand MagellanC. Vasco da GamaD. Marco Polo5、What do we call the process of growing crops?A. AgricultureB. FarmingC. CultivationD. All of the above6、What is the main ingredient in sushi?A. RiceB. NoodlesD. Potatoes7、选择题：What is the capital of Canada?A. TorontoB. OttawaC. VancouverD. Montreal8、What is the opposite of "safe"?A. SecureB. DangerousC. ProtectedD. Guarded9、选择题：What is the name of the famous British author who wrote "1984"?A. J.K. RowlingB. George OrwellC. J.R.R. TolkienD. Agatha Christie10、How do you say "fish" in French?A. PoissonB. PescadoC. FischD. Pesce11、选择题：What is the name of the planet we live on?A. MarsB. EarthC. VenusD. Jupiter12、What do you call a young owl?A. OwletB. ChickC. FledglingD. Nestling13、How many days are there in a week?A. FiveB. SixD. Eight14、选择题：What is 15 - 5?A. 5B. 6C. 10D. 1115、What do you call a person who operates a machine?A. OperatorB. TechnicianC. EngineerD. Mechanic16、What is the boiling point of water in degrees Celsius?A. 50B. 75C. 100D. 15017、What is the name of the place where we keep our clothes?A. LibraryB. ClosetC. KitchenD. Bathroom18、选择题：How many sides does a triangle have?A. 2B. 3C. 4D. 519、选择题：What is the capital city of Japan?A. SeoulB. BeijingC. TokyoD. Bangkok20、选择题：What is the name of the famous landmark in London?A. Big BenB. Eiffel TowerC. Statue of LibertyD. Colosseum二、听力题(共计20题，共40分)1、听力题：The chemical formula for chromium(III) oxide is ______.2、听力题：An astronaut experiences weightlessness in ______ (space).3、听力题：The Earth's interior contains both solid and ______ materials.4、听力题：The weather is _____ outside today. (nice)5、听力题：A ____ has soft fur and enjoys cuddling with people.6、听力题：A __________ is a geological feature that can impact local ecosystems.7、听力题：A ____ is a curious animal that likes to sniff around.8、听力题：A neutral solution has a pH of ______.9、听力题：She has a ___ of shoes. (pair)10、听力题：They are _____ (friends).11、听力题：The chemical formula for vinegar is ______ acid.12、听力题：The city of Dublin is the capital of _______.13、听力题：A __________ is a process that involves the breaking and forming of chemical bonds.The __________ is a mountain chain in Europe.15、听力题：My aunt enjoys baking ____ (cookies) for the holidays.16、听力题：A __________ is a unit of measurement for chemical compounds.17、听力题：I have a ______ in my backpack. (notebook)18、听力题：My mother is a ______. She helps with homework.19、听力题：Genghis Khan founded the ________ Empire.20、听力题：The main ingredient in soap is _____.三、填空题(共计20题，共10分)1、填空题：The __________ (历史事件) can be interpreted in different ways.2、填空题：In art class, we use ______ (颜色) to create beautiful paintings. I like to draw ______ (动物) and nature.3、填空题：A garden has many different types of _____ (植物).4、填空题：A ________ (国家公园) protects nature and wildlife.5、填空题：The ______ (植物纤维) can be used for making clothes.6、填空题：A turtle's shell protects it from ______ (捕食者).The __________ (历史的情感共鸣) bridge divides.8、填空题：Ferns do not have _____ (花).9、填空题：The _______ (鲸鱼) is a gentle giant.10、填空题：The owl has excellent ______ (听力).11、填空题：We visit the ______ (音乐会) to enjoy live performances.12、s can grow very ______ (高大). 填空题：Some tre13、填空题：My aunt is a great __________ (演讲者).14、填空题：My pet _____ loves to play fetch.15、填空题：The _____ (草地) is a great place for picnics.16、填空题：My favorite activity is ______ (骑自行车).17、填空题：The weather is _______ (非常凉爽).18、填空题：I have a special place for my ____.19、填空题：The ________ was a famous explorer who sailed around the world.20、填空题：The _______ (小蜻蜓) catches insects in the air.。

三参数弹性地基梁的挠曲

三参数弹性地基梁的挠曲


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I.E. Avramidis, K. Morfidis / International Journal of Solids and Structures 43 (2006) 357–375
only in the case of slender beams. It is well-known that the error in shear force and moment distribution can become significant in the case of foundation beams with small length-to-depth ratio subjected to closely spaced discrete column loads, as well as in the case of flanged beams and beams with sandwich-like cross-section. To confront this problem, the well-known Timoshenko beam model, in which the effect of transverse shear deflections is considered, can be used. While fairly realistic and efficient models of the material properties and the mechanical behavior of the beam can be established by using the Timoshenko or even the Bernoulli–Euler theory, the characteristics that represent the mechan
【国家自然科学基金】_安全性测试_基金支持热词逐年推荐_【万方软件创新助手】_20140801

【国家自然科学基金】_安全性测试_基金支持热词逐年推荐_【万方软件创新助手】_20140801


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凹凸棒石粘土对灌淤土养分含量及小麦生长的影响

凹凸棒石粘土对灌淤土养分含量及小麦生长的影响

文章编号:1673-5196(2008)06-0082-03凹凸棒石粘土对灌淤土养分含量及小麦生长的影响袁惠君1,刘左军1,张旭霞1,陈晓前1,李春雷2,郝远3(1.兰州理工大学生命科学与工程学院,甘肃兰州730050;2.兰州理工大学石油化工学院,甘肃兰州730050; 3.兰州理工大学材料科学与工程学院,甘肃兰州730050)摘要:通过小麦盆栽研究凹土对灌淤土养分含量及小麦生长和产量性状的影响.结果表明:施用凹土不影响土壤速效养分,但用量大于40g/kg会降低碱解氮含量,使生物量、地上部生物量、穗长、孕小穗数、穗粒数和穗粒重下降,不孕小穗数增多;小于40g/kg时不影响上述产量性状;千粒重随凹土用量的增大而增加,在80g/kg时达到最大,增加13.01%.关键词:凹土;灌淤土;养分含量;小麦中图分类号:Q948.113;S156.2;S158.3文献标识码:AEffects of attapulgite clay on nutrient content in irrigation-siltedsoil and wheat growthYU AN Hu-i jun1,LIU Zuo-jun1,ZHA NG Xu-x ia1,CHEN Xiao-qian1LI Chun-lei2,H AO Yuan3(1.College of Life Science and Engin eering,Lan zhou Un iv.of Tech.,Lanzh ou730050,China; 2.C ollege of Petr ochem ical Techn ology, L anz hou U niv.of Tech.,Lan zhou730050,China; 3.Colleg e of M aterials S cience and En gineering,Lanzhou U niv.of T ech.,Lanzhou 730050,China)Abstract:Effects of attapulg ite clay on nutrient content in irrigation-silted soil,w heat grow th and y ield com po nents w ere studied by means of planting the w heat in a pot.Results show ed that applying the at-tapulg ite clay into the soil had no influence o n its quick-acting nutr ient.H ow ev er,the N-content o f the soil w ould decrease w hen the do se of attapulgite clay in soil w as m ore than40g/kg.The biomass,abov e-gro und biom ass,spike leng th,spikelet num ber,g rain num ber and grain w eigh w ould be decreased while sterile spikelet num ber increased.When the dose w as less than40g/kg,no effects w ere dem onstrated on these y ield components.With foregoing do se of attapulgite clay in so il incr eased,kilo g rain w eig h w o uld be incr eased.When the dose of attapulg ite clay in so il w as80g/kg,the to p kilo grain w eig h w ould be achieved.Key words:attapulg ite clay;irrigation-silted soil;nutrient content;w heat凹凸棒石粘土(简称凹土)是一种天然稀有非金属粘土矿物,其矿物几乎遍及世界各地,但具有工业意义的矿床并不是很多,仅限于美国、中国、印度、西班牙等国.我国自1976年在江苏六合小盘山首次发现凹土矿之后,相继在江苏、安徽、山东、辽宁等14个省区发现了凹土矿点,产量以江苏盱眙居首位,为世界优质矿藏[1-4].近年来在河北、山西和甘肃等地收稿日期:2008-05-09基金项目:科技部国际科技合作项目(2004DFB00200)作者简介:袁惠君(1974-),女,甘肃天水人,硕士,讲师.又发现凹土矿,尤其是在甘肃中、西部发现大型含碘凹凸棒石矿,是世界上首次发现的含碘种属,储量达到5.5亿吨[5-6].加强凹土的开发利用研究,拓宽应用领域是凹土产业发展的关键.凹土不仅在化工、建材、造纸、医药、食品和硅酸盐等工业方面得到广泛应用,它还是一种重要的农用矿产资源,主要利用其良好的吸附性、湿水后的粘性和可塑性用在农药、肥料及土壤改良等方面.有研究表明:将土壤悬浮液加入凹土培养基中能刺激根的生长[7],临泽凹土能促进园茄、番茄、黄瓜、草莓、第34卷第6期2008年12月兰州理工大学学报Jo ur nal of L anzho u U niv ersity of T echno lo gyVo l.34No.6D ec.2008玉米增产,提高园茄、玉米的粗蛋白含量[5].可见,凹土在促进农作物增产,改良果实品质方面大有可为.但长期以来,凹土的应用研究主要集中在提纯方法、改性、吸附性能等方面[8-10],以凹土粉作为土壤改良剂在农业上的应用研究非常少,凹土对土壤理化性质及小麦生长的影响未见报道.本文研究凹土对土壤养分的影响,并以小麦为实验材料,通过分析小麦孕穗情况及生物量等性状,研究凹土对作物的产量性状的影响,为凹土在农业上的进一步开发利用提供理论依据.1材料与方法1.1实验材料凹土采用江苏盱眙产的提纯凹土.以灌淤土为小麦盆栽实验用土,土壤采自甘肃省农业科学院土肥研究所试验田,取样深度为0~20cm,土壤基本性质见表1.土壤风干后,过5mm土样筛.盆钵为元素分析专用盆.小麦品种为永良4号,由甘肃省农业科学院提供.1.2方法小麦盆栽实验在温室进行.将凹土与土壤充分混匀后分装成5盆,每盆装土9kg,施尿素3.17g 和普通过磷酸钙11.0g,灌水量控制为田间持水量的45%.凹土添加量为0(对照)、20、40、80、160 g/kg.每盆播种25粒,待出苗后统计出苗率并且每盆定苗至15株.定苗后进行水分控制,每两天称盆重,并灌水至定值.收获后60e烘干,测定穗长、孕小穗数、不孕小穗数、生物量、地上部分生物量(不包括小麦籽粒)、千粒重,重复5次.表1供试土壤基本性质Tab.1Basic properties of soil tested水解氮/ (mg#kg-1)速效磷/(mg#kg-1)速效钾/(m g#kg-1)土壤各级团聚体含量%>5mm5~2mm2~1m m1~0.5mm0.5~0.25mm0.25~5mm>0.25m m108.9095.43307.600.24 1.02 1.41 2.01 5.199.6210.06土壤养分的测定中,碱解氮含量测定采用碱解扩散法,速效磷含量的测定采用碳酸氢钠浸提钼蓝比色法测定,速效钾含量的测定采用乙酸铵提取火焰光度法[11].用SPSS13.0软件进行统计分析.2结果与讨论2.1凹土对土壤速效养分的影响多变量方差分析结果(见表2)表明:土壤中施用凹土总体上不影响碱解氮、速效钾、速效磷含量(P>0.05),但用量大于40g/kg时碱解氮含量下降,用量40g/kg时速效钾的含量降低.这可能由于表2凹土对土壤速效养分的影响Tab.2Effect of attapulgite clay in soil on quick-acting soilnutrient凹土用量/ (g#kg-1)碱解氮/(m g#kg-1)M?SD速效磷/(mg#k g-1)M?S D速效钾/(mg#kg-1)M?SD0108.90?3.0595.43?8.57307.60?2.93 20107.13?0.3597.40?4.81302.70?1.42 40112.77?8.4992.00?11.82298.70?3.90* 8089.07?3.55*95.93?1.51300.67?2.83 16087.30?2.23**99.30?0.82302.97?3.70注:M表示平均数;SD表示标准方差;/*0表示与CK处理的差异显著(P<0.05),/**0表示与CK处理的差异极显著(P<0.01).凹土具有很强的吸附性,速效养分被吸附使含量下降.2.2凹土对小麦生物量的影响由表3可见,凹土用量小于40g/kg时不影响地上部生物量和生物量,大于40g/kg时两者都明显下降,这可能是由于过量施用凹土导致土壤板结,影响作物的生长.表3凹土对小麦生物量的影响Tab.3Effect of attapulgite clay on wheat's biomass凹土用量/(g#k g-1)测定株数生物量/gM?SD M C地上部生物量/gM?SD M C 075 2.29?0.06aA 1.15?0.23aA2075 2.35?0.15aA 1.15?0.23aA4075 2.31?0.14aA 1.13?0.26aA8075 2.01?0.08bB0.98?0.24bB16075 1.53?0.05cC0.71?0.11cC注:M表示平均数;SD表示标准方差;M C表示多重比较,同一列字母相同者,为差异不显著;字母不同者,大写字母表示差异极显著(P<0.01),小写字母表示差异显著(P<0.05). 2.3凹土对小麦产量构成因子的影响表4显示,凹土用量大于40g/kg时穗长、孕小穗数、穗粒数、穗粒重下降,不孕小穗数增多,但千粒重随凹土用量的增大而提高,凹土用量80g/kg时千粒重最大;小于40g/kg时影响不明显.#83#第6期袁惠君等:凹凸棒石粘土对灌淤土养分含量及小麦生长的影响表4凹土对小麦产量性状的影响Tab.4Effect of attapulgite clay on wheat yield components凹土用量/ (g#kg-1)测定株数穗长/cmM?SD M C孕小穗数M?S D M C不孕小穗数M?SD M C穗粒数(粒)M?S D M C穗粒重/gM?SD M C千粒重/gM?SD M C增幅/%0758.33?0.52aA11.87?0.35aAB 1.52?0.79b C32.32?1.95aA 1.14?0.04aA34.20?1.64cC-20758.33?0.25aA11.84?0.62aAB 1.38?0.59b C32.17?2.08aA 1.20?0.08aA35.56?0.86bcBC 3.98 40757.91?0.22abA11.99?0.42aA 1.56?0.68bBC30.63?1.44aA 1.17?0.06aA36.50?0.62bB 6.73 80757.55?0.37bA10.87?0.78bB 1.95?0.99aAB25.89?1.74bB 1.03?0.07bB38.65?1.64aA13.01 16075 6.85?0.18cB9.93?0.62cC 2.19?1.43aA21.56?1.02cC0.83?0.05cC36.18?0.58bB 5.79注:M表示平均数;SD表示标准方差;M C表示多重比较,同一列字母相同者,为差异不显著;字母不同者,大写字母表示差异极显著(P<0.01),小写字母表示差异显著(P<0.05).3讨论凹凸棒石是一种层链状结构的含水铝镁硅酸盐矿物,其晶体呈棒状、纤维状,层内贯穿孔道,表面凹凸相间布满沟槽,具有较大的比表面积,大部分的阳离子、水分子和一定大小的有机分子均可直接被吸附进孔道中.因此,凹凸棒石具有良好的吸附作用、催化作用、流变性和耐热性等性质[12].王丽等用NH4Cl和(NH4)2CO3对凹凸棒土进行改性研究了凹土对钾、钙、镁3种离子的离子交换作用,结果表明溶液中3种离子浓度都降低,改性凹土对这3种离子吸附作用明显[13].可见,凹土能吸附土壤中的速效N、速效K,使速效养分含量下降.土壤团粒结构决定土壤的物理肥力,同时也决定土壤的通气性和透水性,粒径0.25~5.00m m的团粒含量越高,土壤透气度越大,则土壤涵养水分和供应植物所需水分的能力越高[14].凹土在小于40 g/kg时能有效促进土壤中0.25~5.00mm粒径团粒结构的形成,但土壤中过多施用会破坏土壤结构,引起土壤板结.文献报道将土壤悬浮液加入凹土培养基中能刺激根的生长[7].范迪富等研究表明土壤中施用凹凸棒石粘土能提高根系土pH值,不影响芦蒿产量[15].土壤团粒结构、根的生长、根系土pH 值的改变、凹土的吸附与离子交换作用都会影响作物对水肥的吸收利用效率,改变养分的供给,影响作物的生长.土壤中添加凹土总体上不影响土壤速效养分含量.从凹土对小麦经济性状的影响来看,单独施用凹土增产效果不明显,但能增加单粒籽粒的重量,因此可利用凹土与其他肥料配合,改善土壤对作物的养分供给,达到增产和调控作物生长、改良可食部分品质的目的.4结论1)土壤中适量施用凹土不影响土壤速效养分,但过多施用会降低碱解氮含量.2)凹土用量大于40g/kg时生物量、地上部生物量、穗长、孕小穗数、穗粒数和穗粒重下降,不孕小穗数增多;小于40g/kg时不影响上述产量性状.3)千粒重随着凹土用量的增大而增加,在80 g/kg时达到最大,与对照组相比增加13.01%.参考文献:[1]胡涛,钱运华,金叶玲,等.凹凸棒土的应用研究[J].中国矿业,2005,14(10):73-76.[2]朱海清,周杰.凹凸棒石粘土的开发利用现状及发展趋势[J].矿产保护与利用,2004(4):14-17.[3]周济元,顾金龙,周茂,等.凹凸棒石粘土应用现状及高附加值产品开发[J].非金属矿,2002,25(2):5-7.[4]杨婕,陈敬中.江苏盱眙坡缕石的矿物学特征[J].资源调查与环境,2004,25(3):190-196.[5]魏荣道,崔峤.甘肃临泽凹凸棒石粘土矿开发应用研究[J].甘肃科学学报,2005,17(3):43-45.[6]王孝通,崔峤,张国英.临泽杨台洼滩凹凸棒粘土及石膏矿床[J].甘肃地质学报,2005,14(1):90-95.[7]M ARTIN J K,FOST ER R C.A model system for s tu dying thebioch emis try and biology of the root-s oil interface[J].Soil Biol Biochem,1985,17(3):261-269.[8]周济元,丁步彬,顾金龙,等.再论凹凸棒石黏土应用现状及高附加值产品开发术[J].非金属矿,2006,29(5):1-5.[9]M URRAY H H.Overview-clay mineral application s[J].Ap-plied Clay S cien ce,1991,5:379-395.[10]M URRAY H H.T raditional 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