Dynamic Mechanical Behaviour of Polymer Bonded Nd-Fe-B Composite Materials

Magnetic composite materials with varied content of Nd-Fe-B particles in epoxy matrix are examined from a dynamic mechanical perspective. Structural, viscoelastic and magnetic properties of composites have been observed using Scanning Electron Microscope (SEM), Dynamic Mechanical Analysis (DMA) and Super Quantum Interference Device (SQUID) magnetometer, respectively. Experimental results show that magnetic properties and corresponding dynamic mechanical behaviour depend on packing density. Also, results observed by predictive mathematical models suggest that maximal packing factor has a direct impact on elastic behaviour of composites. [doi:10.2320/matertrans.M2011218

Determination of tension strength in the longitudinal and circumferentional direction in glass-polyester composite pipes

Polymer composite pipes with glass fiber reinforcement have today a wide usage in the chemical and process industries. The basic subject of this paper is the determination and distribution of stresses and strains in longitudinal and circumferentional directions of glass-polyester pipes under tension test. Also, the tension strengths in both directions are determined out. Tension test was performed on an electro-mechanical test machine on flat samples and rings obtained by cutting of pipes produced by the method 'Filament winding' with glass fibers reinforcement ±55°. Also, the micromechanical analysis on fracture surfaces was done by SEM, which provided the knowledge about models and mechanisms of fracture on applyed loading.Cevi od polimernih kompozita sa staklenim ojačanjem danas imaju široku primenu u hemijskoj i procesnoj industriji. Predmet ovog rada je određivanje i raspodela napona i deformacija u uzdužnom i obimnom (tangencijalnom) pravcu staklo-poliester cevi pri ispitivanju zatezanjem. Takođe, određena je i zatezna čvrstoća u oba navedena pravca. Ispitivanje zatezanjem je izvedeno na elektromehaničkim kidalicama na ravnim uzorcima i prstenovima sečenim od cevi proizvedenih metodom namotavanja, sa namotavanjem staklenog ojačanja pod uglom ±55°. Mikromehanička analiza je izvedena na površinama preloma korišćenjem SEM, na osnovu koje su pretpostavljeni modeli i mehanizmi nastanka loma usled primenjenih opterećenja

Microstructural characterization of glass-epoxy composites subjected to tensile testing

The main objective of the research presented in this paper was to carry out a statistical-mechanical analysis concerning the tensile test of glass-epoxy composite materials in order to calculate their relevant tension properties and micromechanical structure destruction process. The analysis was done at room temperature, and its results were derived based on the structure of the glass woven 280 g/m², 'twill texture' with the width value of 100 cm, type - Interglass 92125, and epoxy resin type MGS L 135. Samples were shaped by hands with 35% of fabric volume part. The consumed portion of resin was 220 g/m², the thickness of the laminate was 0.308 mm, and the mass of the laminate was 500 g/m2. There were a total of eight layers built in the panel. The micromechanical analysis was derived from the crack surfaces data collected on a scanning electronic microscope, and it showed the mechanisms of damage, and development of cracks until the occurrence of the final break under the tension load.Predmet i cilj istraživanja prikazanih u ovom radu su statičko mehanička ispitivanja na zatezanje staklo-epoksi kompozitnog materijala radi dobijanja njegovih relevantnih zateznih svojstava i mikromehaničke analize oštećenja strukture. Ispitivanja su izvedena na sobnoj temperaturi. Analizirani su kompoziti na osnovu epoksidne smole tipa MGS LR 135 i staklenog platna 280 g/m², 'twill' širine 100 cm, tip - Interglas 92125. Uzorci su oblikovani ručnom metodom sa 35% zapreminskog udela vlakana. Utrošak smole je bio 220 g/m², debljina laminata 0,308 mm a masa laminata 500 g/m2. Ukupno je ugrađeno 8 platana u panelu. Analizom prelomnih površina na skening elektronskom mikroskopu izvedena je mikromehanička analiza kojom se došlo do saznanja o mehanizmima oštećenja i razvoju prsline do konačnog loma pri delovanju zateznog opterećenja

The influence of high and low temperatures on the impact properties of glass–epoxy composites

The aim of this paper is to present the influence of high and low temperatures on the impact properties glass–epoxy composites. The impact strength an is presented for four different glass–epoxy composite structures at three different temperatures, i.e., at room temperature t = 20 °C, at an elevated temperature t = +50 °C and at a low temperature t = –50 °C. Standard mechanical testing was carried out on the composite materials with specific masses of reinforcement of 210 g m-2 and 550 g m-2 and orientations 0°/90° and ±45°. Micromechanical analysis of the failure was performed in order to determine real models and mechanisms of crack and temperature influence on the impact properties

Effect of alkaline solutions on the tensile properties of glass-polyester pipes

Construction materials, traditionally used in process equipment, are today successfully replaced by composite materials. Hence, many pipes are made of these materials. The subject of this study was the influence of liquids on the state of stresses and tensile strengths in the longitudinal and circumferential direction of glass-polyester pipes of a definite structure and known fabrication process. These analyses are of great importance for the use of glass-polyester pipes in the chemical industry. The tensile properties (the ultimate tensile strength and the modulus of elasticity) were tested and determined for specimens cut out of the pipes; flat specimens for the tensile properties in the longitudinal direction and ring specimens for the tensile properties in the circumferential direction. First, the tension test was performed on virgin samples (without the influence of any liquid), to obtain knowledge about the original tensile properties of the material composite studied. Subsequently, the specimens were soaked in alkaline solutions: sodium hydroxide (strong alkali) and ammonium hydroxide (weak alkali). These solutions were selected because of their considerable difference in pH values. The specimens and rings were left for 3, 10, 30 and 60 days in each liquid at room temperature. Then, the samples were tested on tension by the standard testing procedure. A comparison of the obtained results was made based on the pH values of the aggressive media in which the examined material had been soaked, as well as based on the original tensile properties and the number of days of treatment. Micromechanical analyses of sample breakage helped in the elucidation of the influence of the liquids on the structure of the composite pipe and enabled models and mechanisms that produced the change of strength to be proposed.Konstrukcioni materijali tradicionalno korišćeni u procesnoj opremi su danas uspešno zamenjeni kompozitnim materijalima, tako da su i mnoge cevi izrađene od ovih materijala. Uticaj baznih tečnosti na stanje napona i zatezne čvrstoće u uzdužnom i obimnom pravcu staklo-poliester kompozitnih cevi je tema ovog rada. Cevi su definisane strukture i poznatog procesa proizvodnje. Ove analize su od velikog značaja za korišćenje staklo-poliester cevi u hemijskoj industriji. Zatezne osobine (zatezna čvrstoća i modul elastičnosti) su eksperimentalno ispitivane na isečenim uzorcima; ravni uzorci u udužnom pravcu, a uzorci u obliku prstena u obimnom pravcu. Ispitivanje je prvo izvođeno na uzorcima koji nisu bili izloženi uticaju rastvora baza da bi se došlo do saznanja o prvobitnim zateznim svojstvima ispitivanih kompozitnih materijala. Nakon toga, uzorci su stavljeni u rastvore baza natrijum-hidroksida (jaka baza, pH=14) i amonijum hidroksida (slaba baza, pH=12) 3, 10, 30 i 60 dana na sobnoj temperaturi. Nakon toga su ispitivani na zatezanje prema standardnoj proceduri. Poređenje dobijenih rezultata je izvedeno na osnovu rN vrednosti rastvora i broja dana izlaganja rastvorima baza, a na osnovu originalnih zateznih osobina. Mikromehanička analiza se izvodila u odnosu na fotografije sa skening eloktronskog mikroskopa sa prelomnih površina čime se došlo do podataka o uticaju rastvora baza na strukturu kompozitnih cevi i modele i mehanizme koji su dovodili do promene zateznih svojstava