Search results for "composites"

Experimental Study of Vibrations in Face Milling Cutting

2014

The paper consists of a research in designing and experimental analysis using a face milling cutter with round inserts. A general model for the new cutter is proposed taking into consideration multiple aspects regarding monitoring and controling the milling process. A comparison of measured vibrations when cutting with different parameters for two constructions of the milling head is presented. The objective of this vibration comparison is to verify wether the new design behaves in similar way with the classic and proven concept of insert clamping using a central screw.

New Materials Design Through Friction Stir Processing Techniques

2007

Friction Stir Welding (FSW) has reached a large interest in the scientific community and in the last years also in the industrial environment, due to the advantages of such solid state welding process with respect 1(o) the classic ones. The complex material flow occurring during the process plays a fundamental role in such solid state welding process, since it determines dramatic changes in the material microstructure of the so called weld nugget, which affects the effectiveness of the joints. What is more, Friction Stir Processing (FSP) is mainly being considered for producing high-strain-rate-superplastic (HSRS) microstructure in commercial aluminum alloys. The aim of the present research…

Wear rates and wear mechanisms of alumina-based tools cutting steel at a low cutting speed

1997

Abstract Three ceramic insert materials, zirconia-toughened alumina (Al 2 O 3 –7vol%ZrO 2 ), mixed-based alumina (Al 2 O 3 –TiN–TiC–ZrO 2 ) and alumina reinforced with SiC whiskers (Al 2 O 3 –SiC w ), were used to cut AISI 1040 steel at 3.9 m s −1 . In addition, a traditional grade P10 insert (WC–TiC–Co) was tested. The lifetimes, according to KT/KM and VB B criteria, were determined using a profilometer and by image processing. The worn zones were observed with scanning electron microscopy techniques. Adhesion and plastic deformation were dominant wear mechanisms in zirconia-toughened alumina, mixed-based alumina and sintered carbide P10, both in the craters and in the cutting edges. As we…

Functionality of endothelial cells on silk fibroin nets: Comparative study of micro- and nanometric fibre size

2007

Biomimetic material design, such as mimicking nanostructured components of the extracellular matrix, is an actual challenge for biomaterial research with a high impact on tissue engineering and regenerative medicine. Thus, understanding the cellular response at the cell biological and molecular level and the consequences of various chemically or physically modified biomaterials is highly important. In the present study we assessed the response of human umbilical vein endothelial cells (HUVEC) and outgrowth endothelial cells (OEC) from endothelial progenitor cells to different variants of nanofibrous silk fibroin nets in comparison to microfibrous silk fibroin scaffolds with regard to cellul…

Apparent interfacial shear strength of short-flax-fiber/starch acetate composites

2016

Abstract The paper deals with an indirect industry-friendly method for identification of the interfacial shear strength (IFSS) in a fully bio-based composite. The IFSS of flax fiber/starch acetate is evaluated by a modified Bowyer and Bader method based on an analysis of the stress–strain curve of a short-fiber-reinforced composite in tension. A shear lag model is developed for the tensile stress–strain response of short-fiber-reinforced composites allowing for an elastic-perfectly plastic stress transfer. Composites with different fiber volume fractions and a variable content of plasticizer have been analyzed. The apparent IFSS of flax/starch acetate is within the range of 5.5–20.5 MPa, de…

Experimental and numerical evaluation of sandwich composite structures

2004

The main problem working with sandwich composite structures is their intrinsic anisotropy and non-homogeneity that does not allow their correct modelling. Nowadays the available data on mechanical properties of complex structures, necessary to allow a correct and reliable design, are not sufficient. The aim of the present work is to extend the knowledge of mechanical properties both on single components and on complete structures, focusing on the effects induced by different kind of skin arrangements (Kevlar, glass and carbon fibres). Compressive, shear and flexural tests were performed for a complete static mechanical characterisation of the sandwich structure both on each single component…

Nano structured systems synthesised by ionizing radiation

2009

Jauni viedie materiāli no multifāzu polimēru kompozīcijām, to fizikāli-mehānisko, deformatīvo un struktūras īpašību izmaiņas jonizējošā starojuma un …

2014

Promocijas darbā pētītas poliolefīnu – multifāzu kompozīcijas ar elastomēriem un šķērssaistīšanās promotoriem. Izvērtēta radiācijķīmiskās modificēšanas un lielas indukcijas magnētiskā lauka (B = 1,0-1,7 T) ietekme uz pētīto kompozītsistēmu stiprības-deformācijas, struktūras īpašībām, kā arī novērtēta magnētiskā lauka un jonizējošā starojuma mijiedarbības ietekme uz poliolefīnu makromolekulu šķērssaistīšanās efektivitāti. Iegūtas jaunas teorētiskas un praktiskas atziņas par radiācijķīmiski modificētu poliolefīnu multifāzu kompozīciju ekspluatācijas īpašībām, kas ļāva radīt jaunus uz polipropilēna bāzētus termonosēdmateriālus.

Do zwitterionic species exist in the non-enzymatic peptide bond formation?

2012

The use of proper computational methods and models has allowed answering the controversial question of whether zwitterionic species exist in the mechanism of peptide bond synthesis in aqueous solution. In fact, the different conformations of zwitterionic species open the door to different mechanistic paths.

Intramolecular electron transfer between molybdenum and iron mimicking bacterial sulphite dehydrogenase

2014

Diferrocenyl/diferrocenium substituted dioxido molybdenum(VI) complexes [Fe2MoO2] 2(Fc)/[2(FC)]²⁺ mimic the catalytic active site including the redox subunits as well as the catalytic function of bacterial sulphite oxidases.