Self-piercing riveting connections using aluminium rivets

The development of the self-piercing riveting (SPR) technology in recent years has broadened the application of the technology in the automobile industry. However, the SPR process currently utilises high-strength steel rivets; and the combination between steel rivets with an aluminium car body makes recycling a challenge. The possibility of replacing a steel self-piercing rivet with an aluminium one has thus been raised as an interesting topic. Within this framework, the objective of the present paper is to provide an experimental database on the riveting process using an aluminium self-piercing rivet. An experimental programme has been carried out, where two similar sheets in aluminium alloy 6060 in three different tempers (temper W, temper T4, and temper T6) have been joined by using a self-piercing rivet in three different alloys, i.e. 6082-T6, 7108-T5, and 7278-T6. The influence of the die shape on the SPR of aluminium sheets using aluminium rivets was also considered. Conventional rivets and dies according to the Boellhoff standards were employed. The test results were exploited in terms of the riveting force–displacement curves and cross-sectional geometries of the riveted joints. The test data were also used to validate a 2D-axisymmetric model, which was originally developed at SIMLab for modelling the riveting process using a steel rivet. Finally, the mechanical behaviour of a riveted connection using an aluminium rivet under quasi-static loading conditions (i.e. combined pure shear and pure opening loads) was experimentally studied and compared with corresponding tests using a steel rivet in terms of force–displacement curves.     

Electrochemical reduction of transition metal-substituted silicon,germanium and tin derivatives: I. Cobalt or cobalt and iron complexes

The complexes Ph₃ECo(CO)₃L (E = Si, Ge; L = CO, PPh₃ P(OPh)₃) have been studied by electrochemistry. The reduction potential of these derivatives is less affected by the nature of the ligand L than in the case of [CO(CO)₃L]₂. The electrochemical reduction of the tin complexes [Co(CO)₄]_n[Fe(CO)₂Cp]_3?nSnCl (n = 1–3) showed that the formation of the radical anion occurred with tin-cobalt rather than tin-chloride bond rupture. Electrolysis of these tin derivatives did not give any distannane containing transition metal groups. However it can be noted that the Fe(CO)₂Cp group stabilized these tin complexes.     

Mechanism of nucleophilic substitution at silicon: kinetic evidence on the slow formation of a pentacoordinate silicon intermediate

Kinetic studies of various coupling reactions between silicon derivatives (SiF, SiCl, SiOMe, SiH) and organometallic reagents (RMgX, RLi) were performed for systems involving retention and inversion of configuration. The results show that for both stereochemical courses, the rupture of the SiX bond is not the rate determining step. Results are in good agreement with the rate determining formation of a pentacoordinate silicon intermediate.     

Synthesis, structural characterization, and transmetalation reactions of a tetranuclear magnesium silsesquioxane complex

The reaction of a silsesquioxane trisilanol with methylmagnesium chloride leads to an unprecedented tetranuclear magnesium silsesquioxane complex 1 in high yield. The crystal structure shows an unusually short Mg-Cl bond, indicative of an electron-deficient magnesium atom; 1 has been used as transmetalation agent for the synthesis of metal silsesquioxane complexes. Transmetalation activity was low, but can easily be followed by multinuclear NMR. Crystal data for 1: C(78)H(142)Cl(2)Mg(4)O(26)Si(14).6(C(4)H(8)O), a = 15.744(1) A, b = 26.526(2) A, c = 16.917(1) A, beta = 113.229(2) degrees, monoclinic, P2(1)/n, Z = 2.     

Fragmentation of neutral Cn clusters (n = 9): experimental and theoretical investigations

We report on experimental and theoretical efforts designed to understand the fragmentation of small carbon clusters. Experimentally, a new detection system for high velocity fragments has been recently developed allowing the fragmentation of high velocity clusters to be totally recorded [1]. Results for the branching ratios of deexcitation of C₅ and C₉ formed by electron capture in high velocity collisions are presented. Theoretically, the dissociation dynamics of C₅ has been investigated using a kinematical model based on the statistical theory of Weisskopf. In this model various structural quantities (geometries, dissociation energies, harmonic frequencies), are required for both the parent cluster and the fragments. They have been calculated within DFT and coupled-cluster formalisms for C_n up to n = 9. In all cases, a strong correlation between measured branching ratios and calculated dissociation energies is observed.     

Bahlsen Keksfabrik KG, Hannover Mikroskopie und Lebensmitteltechnologie

Ohne ZusammenfassungDie ausführliche Arbeit erschien in der Dtsch. Lebensmittelrundschau 58, 277 (1962).