The group equivalent reaction: An improved method for determining ring strain energy

1990 ◽  
Vol 67 (11) ◽  
pp. 907 ◽  
Author(s):  
Steven M. Bachrach
Keyword(s):  
Strain Energy ◽  
Improved Method ◽  
Ring Strain

scholarly journals Entropy-Based Method to Evaluate Contact-Pressure Distribution for Assembly-Accuracy Stability Prediction

Entropy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 322 ◽  
Author(s):  
Xiao Chen ◽  
Xin Jin ◽  
Ke Shang ◽  
Zhijing Zhang
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Strain Energy ◽  
Original Method ◽  
Stability Prediction ◽  
Improved Method ◽  
Contact Pressure Distribution ◽  
Assembly Accuracy ◽  
Significant Research ◽  
The Stability

Assembly accuracy and accuracy stability prediction are significant research directions for improving the reliability and efficiency of precision assembly. In this study, an improved method for assembly accuracy stability prediction, based on the contact-pressure distribution entropy, is presented. By using the contact-pressure distribution as the evaluation parameter instead of the strain-energy distribution, the improved method can not only predict the assembly accuracy of precision assembly more efficiently, but also predict the stability of the assembly accuracy with variations in the ambient temperature. The contact pressure has a clearer mechanical significance than strain energy density in the assembly process, which can be used to distinguish the actual contact area from the contact surface. Hence, the improved method is more efficient and accurate than the original. This study utilizes the same case used in the original method and an additional case from the actual production process to verify the improved method. The correctness and validity of the improved method are proved by these case studies.

scholarly journals An Improved Method to Detect Damage Using Modal Strain Energy Based Damage Index

2012 ◽  
Vol 15 (5) ◽  
pp. 727-742 ◽  
Author(s):  
B.L. Wahalthantri ◽  
D.P. Thambiratnam ◽  
T.H.T. Chan ◽  
S. Fawzia
Keyword(s):  
Strain Energy ◽  
Damage Index ◽  
Improved Method ◽  
Modal Strain Energy

scholarly journals A Theoretical Investigation of the Ring Strain Energy, Destabilization Energy, and Heat of Formation of CL-20

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
John A. Bumpus
Keyword(s):  
Strain Energy ◽  
Parent Compound ◽  
High Energy ◽  
Heat Of Formation ◽  
Van Der Waals Interactions ◽  
High Energy Density ◽  
Ring Strain ◽  
Torsional Strain ◽  
Cage Compound ◽  
High Energy Density Material

The cage compound CL-20 (a.k.a., 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, HNIW, or 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.03,11.05,9]dodecane) is a well-studied high-energy-density material (HEDM). The high positive gas- (ΔfHg°) and solid- (ΔfHs°) phase heat of formation values for CL-20 conformers have often been attributed to the strain energy of this cage compound and, by implication, to the conventional ring strain energy (CRSE) inherent in isowurtzitane which may be viewed as a “parent compound” (although not the synthetic precursor) of CL-20. ΔfHg° values and destabilization energies (DSEs), which include the contribution from CRSE, were determined by computation using a relatively new multilevel ab intio model chemistry. Compared to cubane, isowurtzitane does not have an exceptionally high CRSE. It is about the same as that of cyclopropane and cyclobutane. These investigations demonstrate that instead of the CRSE inherent in the isowurtzitane parent compound, the relatively high ΔfHg° and DSE values of CL-20 conformers must be due, primarily, to torsional strain (Pitzer strain), transannular strain (Prelog strain), and van der Waals interactions that occur due to the presence of the six >N–NO2 substituents that replace the six methylene (–CH2–) groups in the isowurtzitane parent compound. These conclusions are even more pronounced when 2,4,6,8,10,12-hexaazaisowurtzitane is viewed as the “parent compound.”

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