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- Lorentzon, J., et al.
(författare)
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A theoretical study of the electronic spectra of pyridine and phosphabenzene
- 1995
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Ingår i: Theoretica Chimica Acta. - 0040-5744. ; 92, s. 67-81
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Tidskriftsartikel (refereegranskat)abstract
- The electronic excitation spectra of pyridine and phosphabenzene have been studied using theoretical methods. The electronic states are described by wave functions derived from second-order perturbation theory based on multiconfigurational reference functions. The study includes singlet and triplet valences excited states as well as a number of Rydberg states. For both molecules the transition energies to the two lowest π → π* excited singlet states are known from experiment and reproduced with an accuracy of 0.15 eV or better, while then → π* transition energies are predicted with a somewhat uncertain error of about 0.2 eV. The calculations suggest the lowestn → π* transition detected experimentally in pyridine corresponds to an adiabatic transition. 43 electronic states have been determined in each of the molecules.
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| 2. |
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| 3. |
- Lorentzon, M., et al.
(författare)
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Influence of intermediate loading rates and temperature on the fracture toughness of ordinary carbon-manganese structural steels
- 1998
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Ingår i: Fatigue & Fracture of Engineering Materials & Structures. - : Wiley. - 8756-758X .- 1460-2695. ; 21:7, s. 805-817
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Tidskriftsartikel (refereegranskat)abstract
- Three-point bend and compact tension specimens, taken from beam sections of modern and older ordinary C-Mn structural steels, were tested at intermediate loading rates at room temperature and -30°C. The experimental work, except the loading rates used, was performed according to ASTM E-813. In order to investigate transferability of data, full-scale beam sections were also tested at intermediate loading rates. The fracture toughness of C-Mn structural steels depends strongly on the loading rate, and decreases rapidly with increasing loading rate at and just above the maximum prescribed in ASTM E-813. Fracture toughness data for structures exposed to intermediate loading rates indicate the requirement for testing at appropriate loading rates. The behaviour of full-scale structural elements subjected to intermediate loading rates can, provided certain conditions are fulfilled, be predicted from data obtained from small laboratory specimens
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| 4. |
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| 5. |
- Lorentzon, M., et al.
(författare)
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On the effect of quasi-static loading rates upon the fracture toughness of ordinary structural steels
- 1996
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Ingår i: Mechanisms and mechanics of damage and failure. - : EMAS. - 0947817905 ; , s. 443-
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Konferensbidrag (refereegranskat)abstract
- For a cracked structural component the crack tip loading rate very often exceeds the maximum rate prescribed in current fracture toughness standards, e.g., ASTM E813. In a previous work, Lorentzon and Eriksson, it was found that loading rates at and just above the ASTM limit significantly affect the fracture toughness of ordinary structural steels. The effect of the loading rate upon the stress and strain distribution around a mode I plane strain crack tip has been calculated with the finite element method. A boundary layer formulation based upon Westergaard's exact analytical solution for an infinite plate and a Perzyna visco-plastic material model has been used. The results show that viscous effects are significant only very close to the crack tip.
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