Effects of Shielding Gas Pureness on Quality of Orbital TIG Welded Austenitic Stainless-Steel Joints

Aim of this research was determination of effects of shielding and backing gas pureness on quality of welded joints produced from austenitic stainless-steel grade X5CrNi18-10 (1.4301) pipes Ø 50.8 x 1.5 mm by orbital TIG welding without use of additional material. In the case of stainless steel, it is of importance not only to prepare shielding of the molten metal pool but as well protection of welded joint root from oxygen, which causes formation of colorful oxide layers. Presence of oxidized layer primarily decreases corrosion resistance of stainless-steel. Performed examination included: chemical composition of welded join material, delta ferrite testing, non-destructive joint testing, visual testing with discoloration assessment from face and root side (acc. to Danish Force Technology Institute report 93.34 and American ASME BPE-2012 norm), radiographic testing, destructive welded joint testing. Metallurgical shielding of the welded joint face was produced with Argon 5.0 pure, with a flow rate of 8 dm3/min. Root of welded joint was at first protected with Argon 5.0 pure, then argon-atmospheric air mixtures were used. Backing gas flow rate was set to achieve a relative pressure of 300 Pa. Quantity of residual oxygen in gas mixture was selected based on Danish Force Technology Institute report 93.34.

3D simulation of transversely isotropic laminated composites in RTM using poromechanics

In the present paper we are trying to establish a 3D simulation framework for Resin Transfer Molding for a laminated preform using the already developed porous media theory for composite materials process simulation purposes. The aim here is to implement the process phenomena, such as coupling of sub-processes that are happening simultaneously, in a full 3D description of the problem. For this purpose, an 8-node solid shell element is employed to be able to handle complex 3D stress-strain states. The development is exemplified considering RTM process where the main focus of the modeling will be on the flow advancement into fiber preform and flow front capturing. To this end, the theory of two-phase porous media is used along with assuming hyper-elastic material response for the fiber bed to formulate the problem. A finite element formulation and implementation of the two-phase problem is developed, and the results are presented accordingly.

Prepare Foam with Injection Molding Method in Acrylonitrile-Butadiene-Styrene (ABS) Matrix Using Chemical Foam Agent

In this study, it is aimed to decrease the weight of the material by using polymer foam materials with lower density instead of commercial polymers which have wide usage area. For this purpose, polymer foam was produced by using an acrylonitrile butadiene styrene (ABS) matrix and an endothermic chemical foam agent using injection molding method. The foam cell morphology, shell layer thickness and mechanical properties of the final part were investigated taking into consideration the weight-changing ratios of the foam agent content (1-1,5-2-2,5-3%).

Properties of Glass fiber hybridized woven Flax and sisal fabric hybrid composites

In recent years, the natural Fiber reinforced composites have attracted significantly among automobiles, wind turbine blades and electrical applications. The only use of natural fiber cannot satisfy the needs of composites. The purpose of this study is to investigate the effect of incorporation of glass fiber at different loading (0, 5 and 10 weight fraction) on physical, moisture absorption and mechanical properties of two different hybrid composition of woven flax and sisal fabric (15/15 and 20/20 weight fraction) separately. Experimental results indicated that increases in incorporation of glass fiber into woven flax and sisal fabric hybrid composites can be significantly increases tensile strength, flexural strength and water resistance of composites significantly but less effect on impact strength and density. Fractography analysis was carried out to examine the nature of fractured specimen using Scanning Electron Microscope.

Mechanical properties and flexural behaviour of fibrous cementitious composites containing hybrid, kenaf and barchip fibres in cyclic exposure

In this study, the mechanical properties and flexural behaviour of the fibrous cementitious composites containing hybrid, kenaf and barchip fibres cured in cyclic exposure were investigated. Waste or by-product materials such as pulverized fuel ash (PFA) and ground granulated blast-furnace slag (GGBS) were used as a binder or supplementary cementitious to replace cement. Barchip and kenaf fibre were added to enhance the mechanical properties and flexural behaviour of the composites. A seven mix design of the composites containing hybrid, kenaf and barchip fibre mortar were fabricated with PFA-GGBS at 50% with hybridization of barchip and kenaf fibre between 0.5% and 2.0% by total volume weight. The composites were fabricated using 50 × 50 × 50 mm, 40 × 40 × 160 mm and 350 × 125 × 30 mm steel mould. The flexural behaviour and mechanical performance of the PFA-GGBS mortar specimens were assessed in terms of load-deflection response, load compressive response, and crack development, compressive and flexural strength after cyclic exposure for 28 days. The results showed that specimen HBK 1 (0.5% kenaf fibre and 2.0% barchip fibre) and HBK 2 (1.0% kenaf fibre and 1.5% barchip fibre) possessed good mechanical performance and flexural behaviour. As conclusion, the effect of fibres was proven to enhance the characteristics of concrete or mortar by reducing shrinkage, micro crack and additional C-S-H gel precipitated from the pozzolanic reaction acted to fill pores of the cement paste matrix and cement paste aggregate interface zone between mortar matrix and fibre bonding.

Machining millimeter-scale deep holes in SiCf/SiC material using femtosecond laser filamentation effect

A 3.5 mm thick SiCf/SiC material was drilled in air environment using a femtosecond laser filament effect. The surface morphology of deep micropores was observed by scanning electron microscopy and the depth and profile of the pores were observed using μm-CT. The variation of entrance diameter, exit diameter and depth variation with laser focus position and processing time was further analyzed. The results showed that as the processing time of femtosecond laser increases, the ablation threshold of the material reached saturation. The exit and entrance diameter also stopped increasing and the aperture tend to saturate. The focus entered the interior of the material, allowing the location of the peak power near the surface of the material. So the entrance aperture was of good quality and the exit aperture was round.

MECHANICAL PROPERTIES (IMPACT STRENGTH) OF PINEAPPLE LEAF FIBRE REINFORCED POLYPROPYLENE COMPOSITES WITH VARIATION OF FIBRE LOADING AND TREATMENT PROCESS.

This paper presents the study of mechanical properties of short pineapple leaf fibre reinforced polypropylene composites. Pineapple leaf fibre (PALF) is one of them that have also good potential as reinforcement in thermoplastic composite. It is the objective of the current research to characterize the mechanical properties of treated and untreated composites of PALF reinforced polypropylene (PP) composite with four different volume fractions of pineapple leaf fiber (PALF) was fabricated, (5 vol%, 10 vol%, 15 vol% and 20 vol%). The study of this PALF-PP composite demonstrates that bulk density of the composite decrease as the volume fraction increased. From the study about impact strength toward the fibre loadings, impact strength and energy absorbed increase as the volume fraction of fibre increased. Untreated PALF gives greater impact strength than treated PALF. From the experiment conducted on impact test and scanning electron microscopy experiment, untreated fibre produce greater impact and absorbed energy than treated fibre. Until 20% of PALF, result showed strength of the composite still rising to prove that 20% of fibre will fabricate finest fibre loading for the PALF-PP composite was observed from the scanning electron microscope (SEM) micrograph as an evidences on compatibility mechanical properties at the intersectional region of composite.

HDPE- Coir composites–fabrication, process parameters and properties

The composites of biodegradable high density polypropylene (HDPE) reinforced with short coir fiber were prepared by melt mixing followed by hot press molding. The effect of fiber addition on some physical and mechanical properties was evaluated. Different process parameters (e.g. mixing time, heating temperature and time, cooling time etc.) were established for good sample preparation The effects of fiber addition on some physical and mechanical properties were evaluated. The mechanical properties were studied via Universal Testing Machine (UTM). The density was increased with the increase of fiber addition. The tensile strength (TS) of fabricated product increased with the increase of fiber addition up to 10% (by wt.) and then decreased continuously. The elongation of fabricated composites was decreased with the increase of fiber addition continuously. The changes in the mechanical properties were broadly related to the accompanying interfacial bonding of HDPE coir composites (HDPECC). To observe the hydrophilicity of the prepared composites was evaluated by the water uptake properties. The interfacial bonding of the fiber and matrix of the coir fiber reinforced composites was studied via scanning electron microscope. It revealed that the introduction of short coir fiber led to a slightly improved mechanical stability of PP- Coir composites.

Short beam strength and flexural behavior of GFRP laminates embedded with short carbon fibers having notch

This paper examines the mechanical performance of eight-layered GFRP laminate embedded with short carbon fibers (SCF). Eight layered GFRP samples are prepared using press molding machine at 40 KN pressure. Notched samples (1 mm deep) at specific position from the center are tested, the doping of SCF is done to evaluate the improvement in mechanical properties using reinforcement at three different proportions 0, 1, 2 and 5 wt.%. The GFRP samples are prepared as per ASTM D2344 and ASTM D7264 for short beam strength (SBS) and flexural and respectively. Samples are tested using Hounsfield HK-50 universal testing machine (UTM) with 50KN capacity at room atmospheric conditions. Results of the experimental analysis justified that the improvement in mechanical properties with increase in doping percentage of SCF while at highest doping value i.e. 5 wt.% mechanical properties reduced.

Effect of repair methods on mechanical behaviors of repair area in composite laminate fuselage skin with different damage size

Composite laminates are widely used in the large civil aircrafts because of their excellent mechanical properties. The maintenance and repair of composite laminates become essential. In this paper, a new adhesive-rivet hybrid repair of composite laminate fuselage skin is presented. For the circular hole damage with the diameter of 90mm and 50mm, the finite element simulation models of adhesive repair and adhesive-rivet hybrid repair were built respectively. Uniform pressure load was applied on these finite element models. The mechanical properties of laminate motherboard, patch and adhesive film for these four models were analyzed. The effects of adhesive repair, adhesive-rivet hybrid repair on mechanical behaviors of repair areas of composite laminate fuselage skins with different damage size were studied. By analyzing the mechanical behaviors of these two repair methods, a suitable repair method can be obtained.