Experimental Verification of HFMI Treatment of Large Structures

Author(s):  
Halid Can Yildirim ◽  
Gary B. Marquis ◽  
Per J. Haagensen

Design recommendations for high frequency mechanical impact (HFMI)-treated welds have been proposed based on available experimental fatigue data of axially-loaded high strength steel specimens which include longitudinal, cruciform and butt welds. Test specimens were of a size appropriate for laboratory study. However, in reality, structures in civil, offshore and ship industries generally include large-scale and more complicated components, such as bridges, cranes, platforms, excavators etc. This paper presents a further validation of the design proposals by considering fatigue data sets which are obtained from large-scale components. The extracted fatigue data from the available literature includes bridge, crane and beam like components. In total, 65 published test results of weld details with various yield strengths (250 ≤ fy ≤ 725 MPa) and stress ratios (−1 ≤ R ≤ 0.56) are presented. All the data are found to be in good agreement with the previously-shown design curves.

2010 ◽  
Vol 36 ◽  
pp. 293-296
Author(s):  
Yoshio Kurosawa ◽  
Takao Yamaguchi

We have developed a technique for estimating vibrations of an automotive body structures with viscoelastic damping materials using large-scale finite element (FE) model, which will enable us to grasp and to reduce high-frequency road noise(200~500Hz). In the new technique, first order solutions for modal loss factors are derived applying asymptotic method. This method saves calculation time to estimate modal damping as a practical tool in the design stages of the body structures. Frequency responses were calculated using this technique and the results almost agreed with the test results. This technique can show the effect of the viscoelastic damping materials on the automotive body panels, and it enables the more efficient layout of the viscoelastic damping materials. Further, we clarified damping properties of the automotive body structures under coupled vibration between frames and panels with the viscoelastic damping materials.


2015 ◽  
Vol 744-746 ◽  
pp. 196-200
Author(s):  
Ning Zhuang ◽  
Hao Dong Sun ◽  
Song Ge

Carbon Fiber Reinforced Plastic (CFRP) has been widely used in large-scale concrete infrastructure’s reinforcement and renovation because of its low weight and high strength, which promotes CFRP application in the field of civil engineering. This paper two aged beams reinforced by CFRP sheet was loaded to failure in four-point bending by laboratory experiment. Then the numerical model was built to simulate the destruction process and compared with test results. Based on the studying of this paper, the changing law of beam’s stress, ultimate bearing capacity growth, failure mode and cracking propagation was investigated during the loading process. The research has guiding significance for the design and construction of concrete structures reinforced by CFRP laminates.


1993 ◽  
Vol 4 (1) ◽  
pp. 31-53 ◽  
Author(s):  
Donald W. Forsyth

AbstractThe site of Nakbe, located approximately 13 km southeast of El Mirador in the far northern part of the Peten, has been investigated by the RAINPEG Project, directed by Richard Hansen, for the last four field seasons. The ceramic sequence from Nakbe has provided us with a much broader view of cultural development in the north-central Peten. We have defined a series of preliminary ceramic complexes that span Middle Preclassic through Late Classic times.The earliest complex at Nakbe, called Ox, which belongs to the Mamom horizon, is one of the two best represented at the site, and definitely associated, late in the period, with large-scale architecture. The principal ceramic groups are the Juventud, Chunhinta, and Pital. The main forms are bowls or basins with flaring walls and direct or everted rims, short-necked jars, cuspidors or semicuspidors, and composite-silhouette bowls. Particularly notable, although rare, are the types Muxanal Red-on-Cream and Tierra Mojada Resist. The Ox Complex is characterized by a high frequency of decoration executed by penetration methods, especially incision and chamfering.The unslipped pottery pertains to the types Achiotes Unslipped and Palma Daub. The latter is marked by a red wash applied to the exterior neck of the jar, the major form in these types. Daub is a form of decoration limited to the Middle Preclassic in this area, as is the chamfering technique on the slipped pottery.The ceramic complexes most similar to Ox are located to the south of Nakbe at Uaxactun and Tikal. The high frequency of chamfering, daub, and other traits strongly link Nakbe to these southern sites during the Middle Preclassic, while sites to the north and southwest, such as Seibal, Altar de Sacrificios, and Becan exhibit more tenuous connections.The Kan Complex belongs to the Late Preclassic period, and is characterized by the Sierra, Polvero, Flor, and Sapote Ceramic Groups. Although associated with the large structures in the site center, Kan ceramics are less abundant than Ox ceramics in our samples. Kan pottery corresponds closely to that of El Mirador and is similar to other complexes of the Chicanel horizon. Particularly noteworthy are everted rims with circumferential grooves and lateral, labial, and medial flanges and ridges. The unslipped pottery of the Kan Complex consists almost exclusively of jars bearing exterior striation from the shoulder to the base.The closest ceramic ties to Kan pottery continues to be with the southern complexes, especially Uaxactun and Tikal. Moreover, the similarity to Seibal is greater during Chicanel times, while Belize appears to differentiate itself ceramically from the Peten during this time. Nevertheless, the Chicanel horizon is the period in which the maximum geographical extent of a ceramic sphere is reached.“Protoclassic” ceramics are rare, but the small amounts recovered at Nakbe are similar to those from El Mirador. The major type is Iberia Orange, found in small quantities in surface contexts. Characterized by hollow, mammiform supports, hooked rims, and orange slip, this Nakbe pottery seems to be more similar to pottery at Seibal than to other complexes with Protoclassic pottery.Early Classic pottery is virtually nonexistent in our excavations, suggesting an insignificant occupation during this period.Late Classic pottery (Uuc Complex) appears in significant quantities at Nakbe, mainly in the outskirts of the site. All of the types and modes defined at El Mirador are found at Nakbe, principally Tinaja Red, Chinja Impressed, Infierno Black, and Carmelita Incised, as well as the polychrome types. Moreover, Codex-style polychrome was also found at the site. As at El Mirador, the Uuc ceramics are not found in association with large-scale architecture, and it appears that Nakbe was not a major center at this time.The major occupations at Nakbe pertain to the Middle and Late Preclassic periods. The abundance of architecture, ceramics, and other classes of artifacts from the Ox Complex provides us with an opportunity to investigate a Middle Preclassic occupation in which there was a much more complex social organization, at least at Nakbe, than had previously been suspected.


2013 ◽  
Vol 648 ◽  
pp. 59-62
Author(s):  
Qi Yin Shi ◽  
Yi Tao Ge ◽  
Li Lin Cao ◽  
Zhao Chang Zhang

In this study, based on the test of the high strength materials of steel-encased concrete composite continuous beam, the ultimate flexural capacity of 8 composite continuous beams are analyzed by using the finite element analysis software ABAQUS. Numerical results show that it is a very good agreement for the load-deflection curves which obtained by finite element method (FEM) and those by the test results, and the error control is less than 8.5%. When selecting and utilizing appropriate cyclic constitutive model, element model and failure criterion of high strength steel and high strength concrete, the accuracy of the calculation can be improved better.


1956 ◽  
Vol 60 (545) ◽  
pp. 331-346 ◽  
Author(s):  
C. L. Bore

SummaryA simple and convenient “ endurance chart” for the presentation of basic fatigue data is described, where static failure is regarded as simply fatigue failure in one cycle of loading.This chart shows the effects of mean stress, residual stress and pre-tension, and displays several interesting features of fatigue data. It is easily constructed directly from fatigue test results, and is very well suited to the calculation of stress concentration effects, including “ plastic relief ” effects.With the aid of such charts the relative fatigue strengths and structural efficiencies of different materials may be readily compared, and it is clearly shown that in certain circumstances a “ high-strength” alloy may in fact have considerably less fatigue strength than a “ medium-strength ” alloy at a given life, or conversely a lower life at a given stress level.It is demonstrated that the fatigue life of a component subjected to combined mean stress and alternating stress may be found only with a knowledge of the complete fatigue characteristics of the material (such as are presented in the endurance chart); and that attempts to estimate fatigue life from spot-value comparisons, such as the fatigue strength at an arbitrary given endurance, can be dangerously inaccurate. A chart of the form described thus forms a valuable step towards the accurate calculation of fatigue life.The method is illustrated by the provision of endurance charts for 14S-T (L.65), 75S-T, and D.T.D.683; and with experimental results for notched components of L.65 and D.T.D.683.An example illustrates the application of the chart to the calculation of the fatigue life for the case of two independent systems of loading acting on a pressure cabin with circular window cut-outs.


2009 ◽  
Vol 9 (4) ◽  
pp. 15891-15957 ◽  
Author(s):  
C. Vigouroux ◽  
F. Hendrick ◽  
T. Stavrakou ◽  
B. Dils ◽  
I. De Smedt ◽  
...  

Abstract. Formaldehyde (HCHO) columns have been retrieved from ground-based Fourier transform infrared (FTIR) campaign measurements in 2004 and 2007 and from UV-Visible MAX-DOAS measurements in 2004–2005 at the NDACC site of Réunion Island (21° S, 55° E). The FTIR and MAX-DOAS daily mean formaldehyde total columns are intercompared in their common measurement period, from August to October 2004. The ground-based data are also compared to correlative SCIAMACHY data. The comparisons account for the vertical sensitivity differences of the data sets, by including their respective averaging kernels. Complete error budgets are also presented. The FTIR and MAX-DOAS daily mean total columns agree very well: no significant bias is observed and the standard deviation of the comparisons is only 8%. Both FTIR and MAX-DOAS HCHO total columns are in good agreement with SCIAMACHY values in the 2004–2005 period, with standard deviations of 21% and 31%, respectively. The same seasonal cycle is observed by the different instruments, with a minimum in austral winter and a maximum in February–March. The FTIR and MAX-DOAS data are confronted with HCHO columns calculated by a global CTM, the IMAGES model. The model underestimates the HCHO columns by 23–29% in comparison with FTIR, and by 15% in comparison with DOAS. This bias might have multiple causes, including an underestimation of OH concentrations in the model (as indicated by a sensitivity study using prescribed OH fields) and/or an underestimated contribution of large-scale transport of HCHO precursors from Madagascar. The latter hypothesis is comforted by the large observed day-to-day variability of HCHO columns, and by the observation that the peak values of FTIR columns can often be associated with free tropospheric transport patterns from source regions over Madagascar to Réunion Island, according to simulations performed with the Lagrangian particle dispersion model FLEXPART.


2021 ◽  
Vol 114 ◽  
pp. 110-115
Author(s):  
Ewa Skorupińska ◽  
Krzysztof Wiaderek ◽  
Maciej Sydor

Influence of technological parameters of the upholstery seams in furniture. Based on the real problem of weak seams in covers of wooden furniture, a multifaceted analysis of the issue was performed. As a result, it was decided to carry out comparative laboratory strength tests of seams made with the use of various technological parameters. For the production of test samples, we used different yarn threads to find the best and sufficiently strong seams for used fabrics. The test results show that not only the thread and fabric used, but also the sewing technology parameters have a significant influence on the seam strength. Overall, these results indicate that to increase the seam strength, it is necessary to choose thread type B with very high strength and low elongation at break. This solution will minimize the risk of broken threads in case of deviation of material features and technological parameters, which can be variable in the long duration of large-scale production.


2009 ◽  
Vol 9 (24) ◽  
pp. 9523-9544 ◽  
Author(s):  
C. Vigouroux ◽  
F. Hendrick ◽  
T. Stavrakou ◽  
B. Dils ◽  
I. De Smedt ◽  
...  

Abstract. Formaldehyde (HCHO) columns have been retrieved from ground-based Fourier transform infrared (FTIR) campaign measurements in 2004 and 2007 and from UV-Visible MAX-DOAS measurements in 2004–2005 at the NDACC site of Réunion Island (21° S, 55° E). The FTIR and MAX-DOAS daily mean formaldehyde total columns are intercompared in their common measurement period, from August to October 2004. The ground-based data are also compared to correlative SCIAMACHY data. The comparisons account for the vertical sensitivity differences of the data sets, by including their respective averaging kernels. Complete error budgets are also presented. The FTIR and MAX-DOAS daily mean total columns agree very well: no significant bias is observed and the standard deviation of the comparisons is only 8%. Both FTIR and MAX-DOAS HCHO total columns are in good agreement with SCIAMACHY values in the 2004–2005 period, with standard deviations of 21% and 31%, respectively. The same seasonal cycle is observed by the different instruments, with a minimum in austral winter and a maximum in February–March. The FTIR and MAX-DOAS data are confronted with HCHO columns calculated by a global CTM, the IMAGES model. The model underestimates the HCHO columns by 23–29% in comparison with FTIR, and by 15% in comparison with DOAS. This bias might have multiple causes, including an underestimation of OH concentrations in the model (as indicated by a sensitivity study using prescribed OH fields) and/or an underestimated contribution of large-scale transport of HCHO precursors from Madagascar. The latter hypothesis is comforted by the large observed day-to-day variability of HCHO columns, and by the observation that the peak values of FTIR columns can often be associated with free tropospheric transport patterns from source regions over Madagascar to Réunion Island, according to simulations performed with the Lagrangian particle dispersion model FLEXPART.


2010 ◽  
Vol 152-153 ◽  
pp. 1835-1838
Author(s):  
Ju Zhang ◽  
Chang Wang Yan ◽  
Jin Qing Jia

In the joint core regions of steel reinforced ultra high strength concrete frame, the forces are complicated. In seismic area or under some exceptional conditions, it is difficult to repair for joint when cracks occur, so crack resistance performance is important. Based on the experiment of steel reinforced ultra high strength concrete (SRUHSC) column to steel reinforced concrete (SRC) beam joint subjected to reversal cycle load, the crack resistance capacity is studied and applied calculation method for crack resistance capacity is proposed. Compared with the test results, the calculated results are in good agreement with them.


2014 ◽  
Vol 22 (3) ◽  
pp. 1-12 ◽  
Author(s):  
Gopal Charan Behera ◽  
Tippabhotla Durga Gunneswara Rao ◽  
Chittem Butchi Kameswara

Abstract The post-cracking behaviour of structures subjected to torsion can be well predicted by Hsu’s softened truss model. The softened truss model is applicable to structures having symmetry in their material properties on all four sides. Wrapping on three faces is a common phenomenon when the top face is provided with a flange or slab. Such a wrapping on three faces of a beam is referred to as a “U” wrap. “U” wraps are better wrapping strategies for distressed structures, as their top face is not accessible for many structures. The material property of an unwrapped face differs from the rest of wrapped faces. For the effective use of wrapping, the unwrapped face needs to be provided with a material having a higher resistance to tension and shear. For this, high-strength concrete in the core is a better option. Here, an attempt is made to predict the torsional capacity of “U” wrapped high-strength concrete beams having an asymmetry in the material using a softened truss model with suitable modifications of the material properties. Efficient algorithms are proposed for the solution of simultaneous equations. The predictions are found to be in good agreement with the experimental test results


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