Experiments on the Determination of Immersed Shell Structure Mobilities via Scale Modeling

1983 ◽  
Vol 105 (3) ◽  
pp. 207-215
Author(s):  
S. S. Sattinger
Keyword(s):  
Frequency Response ◽  
Shell Structure ◽  
Peak Frequency ◽  
Scale Model ◽  
Mode Shapes ◽  
Force Frequency ◽  
Scale Modeling ◽  
Modal Damping ◽  
Acceleration Force ◽  
Force Frequency Response

Experiments were conducted to confirm scaling relations for structural frequency response functions as applied to immersed shell structures using same-material, same-liquid scale models. Accelerance (acceleration/force) frequency response magnitude data were acquired for full-scale and half-scale versions of a fixed-free open cylinder mounted in a rigid vessel. The data confirmed that corresponding frequencies in the model and prototype were in proportion to the inverse of the geometric scale. The peak accelerance magnitudes were normalized by damping to form quantities which should scale despite differences in the corresponding modal damping values. Discrepancies in some of these normalized magnitudes coincided with angular mismatches in mode shapes attributed to minor manufacturing differences in the specimens. Thus, peak frequency responses for a prototype immersed shell structure can be estimated from scale model measurements if typical prototype damping values are known, but the locations of corresponding responses may differ between the model and the prototype in some cases.

scholarly journals Similarity Analysis between Scale Model and Prototype of Large Vibrating Screen

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Zerong Zhang ◽  
Yongyan Wang ◽  
Zhimin Fan
Keyword(s):  
Frequency Response ◽  
Natural Frequencies ◽  
Similarity Theory ◽  
Similarity Criteria ◽  
Scale Model ◽  
Mode Shapes ◽  
Dynamic Stresses ◽  
Operating Condition ◽  
Vibrating Screen ◽  
Scale Down

In order to predict the physical characteristics of the large vibrating screen from its scale-down model, the similarity ratios of the frequency response functions, mode shapes, and dynamic stresses between the prototype and the scale model screen are built according to the similarity theory. The natural frequencies and modal shapes are extracted from the frequency response function by means of modal tests, in which the relative error of the natural frequencies is less than 9% and the modal shapes are consistent between the prototype and the model. The operating condition parameters including dynamic stress, displacement, velocity, and acceleration were also measured and conform to the similarity criteria. The results show that the inherent and operating condition parameters of the large vibrating screen can be obtained from the scale-down model conveniently, which provides an effective method for structural optimization and substructure coupling analysis of the large vibrating screen.

Abstract 5408: PKA and PKC Phosphorylation of Troponin I Canonical Sites Regulate Calcium Sensitivity During Force Frequency Response

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Genaro A Ramirez Correa ◽  
Zhong Xin ◽  
John C Robinson ◽  
Wei D Gao ◽  
Anne M Murphy
Keyword(s):  
Frequency Response ◽  
Troponin I ◽  
Calcium Sensitivity ◽  
Force Frequency ◽  
Transgenic Models ◽  
Human Heart Failure ◽  
Intact Mouse ◽  
Frequency Rate ◽  
Transgenic Lines ◽  
Force Frequency Response

In failing hearts, the force-frequency response (FFR) is blunted, flat or negative. A positive FFR is crucial for healthy myocardium to respond to an increased working demand. There is no consensus in weather a positive FFR relies on myofilament Ca 2+ sensitization or desensitization and weather this is modulated by cTnI phosphorylation. In the present work we aimed to address the FFR and Ca 2+ cycling in intact mouse trabeculae loaded with Fura-2. To achieve this we used two transgenic models with pseudo phosphorylation mutants of troponin I (TnI), TnIDD 22,23 mice, which mimic increased phosphorylation at PKA sites of TnI at Ser 22 and 23 and TnI PKA/PKC mice, which mimic dephosphorylation at same PKA sites and increased phosphorylation at PKC sites of TnI at Ser 42 and 44. We hypothesized that controlling for cTnI phosphorylation will clarify the contribution of cTnI to the differences in force and Ca 2+ dynamics during FFR. When we examined the isometric contraction and Ca 2+ dynamics in each of these lines (TnIDD 22,23 , n= 8; TnI PKA/PKC, n=6) and non transgenic controls (NTG, n=7) we found that all three groups showed a positive FFR, although peak Ca 2+ increased with frequency rate in all three a less steep Ca 2+ transient increase (myofilament Ca 2+ sensitization) was observed in both transgenic lines compared to NTG (TnIDD 22,23 , p= 0.001; TnI PKA/PKC, p=0.03). Additionally, the peak force during the FFR was greater in the TnIDD 22,23 mice compared to NTG (p < 0.0001), suggesting that TnIDD 22,23 mice posses an enhanced frequency rate-related myofilament Ca 2+ sensitivity. WB analysis of Ca 2+ handling proteins including PLB, pPLB, SERCA2a and Ryanodine receptor normalized levels showed no major differences among all three groups, suggesting the differences observed in TnIDD 22,23 mice were not due to altered Ca 2+ handling but rather to myofilament Ca 2+ sensitivity. We conclude that a positive systolic peak FFR is followed by increasing myofilament Ca 2+ esensitization but mimicking increased phosphorylation at PKA sites of TnI Ser 22,23 enhances FFR and Ca 2+ responsiveness. Overall, our results support the concept that myofilament alterations feedback onto Ca 2+ handling mechanisms and these findings have important implications for human heart failure.

Development of a Scale Model for the Dynamic Interaction of a Pile in Clay

1986 ◽  
Vol 108 (3) ◽  
pp. 254-261 ◽  
Author(s):  
D. D. Kana ◽  
L. Boyce ◽  
G. W. Blaney
Keyword(s):  
Dynamic Response ◽  
Cyclic Stress ◽  
Dynamic Interaction ◽  
Scale Model ◽  
Mode Shapes ◽  
Natural Soil ◽  
Model Soil ◽  
Modal Damping ◽  
Time Histories ◽  
Excitation Conditions

Similitude theory is used to develop a scale model for determining the dynamic response properties of a single pile embedded in over-consolidated clay. The basis for the design is a full-scale pile embedded in natural soil, for which dynamic response measurements had been made in previous work. Correlation of the model and prototype results constitutes a major difference in this work over previous efforts using scale models. The model pile material is selected to provide the correctly scaled stiffness and mass properties. The required model soil properties are achieved by developing a mixture of bentonite, aerosil, and veegum. Elastic properties of the model soil are compared with those of the prototype by standard monotonic stress and cyclic stress soil tests. Nonlinearity of the soil stiffness is included in the modeling. Dynamic response of the pile is monitored while excited by impact and swept sine forces at the pile top cap. The results are obtained in terms of time histories for excitation and response at various locations, frequency response functions, natural frequency and mode shapes, and modal damping. Validity of the model is established by comparing the appropriately scaled responses with those of the prototype under similar excitation conditions. It is concluded that the approach should be suitable for measurement of pile/soil dynamic interaction behavior in other types of material and excitation conditions, providing that suitable soil and pile material properties can be selected to allow testing in a one-g environment. Therefore, the scale model approach can be used to verify predictions made by analytical design methods or to provide input parameters for those methods.

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