bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical Properties of Porous Concrete Paving Blocks with Different Sizes of Coarse Aggregate
Authors: Nur Hidayah A.H. , Hasanan Md Nor , Ramadhansyah P.J.
Published: July 2015

This research studies the properties of Porous Concrete Paving Blocks (PCPB) with different sizes of coarse aggregate. Coarse aggregate (CA) is the main component in manufacturing PCPB. Three different sizes of coarse aggregate were used; 1) CA 5 – 10 mm as a control, 2) CA 5 – 8 mm and 3) CA 8 – 10 mm. Furthermore, a series of test were conducted such as density, compressive strength, porosity and skid resistance test to determine the properties of the blocks. It was found that the size of coarse aggregate affects the strength and porosity of the blocks. The strength was reduced approximately in the range 5 % to 17 % from the control blocks. However, it is vice versa with porosity result which porosity of the blocks increased in between 5 % to 10 %. This shows that the blocks suitable for use in vehicle area where help in reduce the water ponding on pavement surface and also increased the skid resistance between the vehicle tires and pavement.
A Review of Advance Nanotechnology against Pavement Deterioration
Authors: Nurulain C.M. , Ramadhansyah P.J. , Norhidayah A.H.
Published: July 2015

This paper presents a review of nanoclay as a latest technology in order to overcome problem due deterioration such as rutting, fatigue, stripping, cracking and so on. Nowadays, with increasing of traffic volume and heavy vehicle conditions of existing road totally fail in order to accommodate this situation during design period. In order to manage this problem the new technology had been create and apply. Previous researches prove that nanotechnology has potential solution to enhance the performance and durability of construction materials. Material properties were characterized using Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). According to previous research there were proved that addition of nanoclay lead great improvements on permanent deformation and fatigue life of hot mix asphalt (HMA). In addition the overall performance of nanoclay as polymer modified asphalt binder was improve in terms of rutting and fatigue cracking resistance compare to non-modified asphalt binder. Therefore, nanoclay itself would be an alternative as modifier to use in the bitumen to improve the lifetime of asphalt pavements.
Polymer-Starch Blend Biodegradable Plastics: An Overview
Authors: Amin Ainatul Mardhiah Mohd , Mohd Sauid Suhaila , Ku Hamid Ku Halim
Published: July 2015

The low degradability behaviour of plastics is an important environmental problem. The end-use of plastic creates waste-disposal problems as these plastics do not readily or naturally degrade and gives severe effect when plastic-waste requires more time to break down. However, as the bio-polymer industries have advanced, biodegradable plastic is being presented as a high promising solution to the environmental problem over the conventional non-biodegradable plastics. As one of the great innovation products in bio-polymer industries, biodegradable plastic can potentially lessen the volume of solid waste and reduce the need for waste dumping sites. Whilst, biodegradable plastic also offers the outstanding properties to resist the brittleness and resistance towards heat. This paper review the potential of biodegradable plastics made from petrochemical-polymers blended with starch, including polyethylene (PE), polycaprolactone (PCL), polyvinyl alcohol (PVOH) polypropylene (PP) and polyvinyl chloride (PVC).
Preliminary Study of HDPE/Kenaf/MMT Nano-Hybrid Biocomposite: Performance of HDPE/Kenaf Biocomposite
Authors: bin Ya’acob Mohamad Asnawi , Ku Hamid Ku Halim , Akhbar Suffiyana , Abdul Rahman Mohd Faizal
Published: July 2015

This work studies the performance of HDPE/kenaf biocomposite by varying the kenaf loading from 10 wt% to 50 wt%. Compounding has carried out by using single screw extruder. The result indicates that at 10 wt% of kenaf loading gave the highest tensile and impact strength which are25.32 MPa and 102.25 MPa respectively. Beside, at 10% to 50% of kenaf loading show increasing tensile modulus, flexural modulus and flexural strength with increment of kenaf fiber but decreasing in tensile strength and impact strength.
Effects of Various Carbon Nanotube Suspensions on A549, THP-1, and Peritoneal Macrophage Cells
Authors: Horie Masanori , Kato Haruhisa , Endoh Shigehisa , Nakamura Ayako , Maru Junko , Shinohara Naohide , Fujita Katsuhide
Published: July 2015

The effects of iron content, fiber length, and stability of carbon nanotube (CNT) suspension on cells were examined. Five kinds of single-wall carbon nanotube (SWCNT) suspensions were prepared: with catalytic iron, without iron, long SWCNTs (stable), short SWCNTs (stable), and short SWCNT (unstable). These suspensions were applied to A549, THP-1, and mouse peritoneal macrophage cells. After a 24-h exposure, the mitochondrial activity, cell membrane damage, intracellular oxidative stress, and expression of cytokine genes were determined. Among these properties of SWCNTs, stability of CNT suspension had the most influence on the cells, whereas the effects of iron content and fiber length were small. The unstable SWCNT suspension caused a substantial increase in intracellular ROS levels. Additionally, the cellular effects of stable multi-wall carbon nanotubes (MWCNTs) were examined. The MWCNT suspension did not show any cellular effects. Overall, influences of CNT suspension on mitochondrial activity and cell membrane damage were small. These results suggest that the physical properties of CNT suspension are important factors for their cellular effects. Thus, CNT suspensions prepared with the same material but having different physical properties would differ in the cellular effects they exert, including cytotoxicity. Therefore, physical characterization of CNT suspensions is essential to the evaluation of CNT toxicity. In particular, stability of CNT suspension notably influenced the intracellular ROS level.
Preparation and Characterization of an In Situ Hydrogel of Self-Assembly Type I Collagen from Shark Skin/Methylcellulose for Central Nerve System Regeneration
Authors: Puttawibul Puttiporn , Benjakul Soottawat , Meesane Jirut
Published: July 2015

Central nerve system degeneration is a crucial problem for many patients. To use an in situ hydrogel formation is an attractive method to treat that problem. An in situ hydrogel was developed for central nerve system regeneration. An acid soluble collagen (ASC) and pepsin soluble collagen (PSC) from the shark skin of the brownbanded bamboo shark (Chiloscyllium punctatum) were used to produce hybridized hydrogels by the biomimetic approach. Collagen was mixed with methylcellulose and used 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as a crosslinker. The hydrogels had various ratios of collagen:methylcellulose: 100:0, 70:30, 50:50, 30:70, and 0:100. Structural, molecular, and morphological organization were characterized and observed by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The DSC results showed that the peak of denatured collagen fibril shifted higher in a 30:70 ratio of collagen:methylcellulose in both ASC and PSC. The FT-IR results indicated that the structure of hydrogels from both ASC and PSC were organized into complex structures. The SEM results demonstrated that the collagen fibril networks were formed in both ASC and PSC hydrogels. The results indicated that the samples containing collagen promise to be an in situ hydrogel for central nerve regeneration.
Directing Chondrogenesis of Primary Chondrocytes by Exposure to Glucose Concentrations
Authors: Uzoechi Samuel C. , Ejeta Kennedy O. , Okoye Goddy C. , Ndubuka Gideon I. , Agbasi Patrick Ugochukwu , Nkem Benjamin I.
Published: July 2015

Since articular cartilage is avascular, both nutrient supply and metabolic waste excretion depend on diffusion. However, the major cause of the progression of articular cartilage defect is the poor inherent regenerative capacity of chondrocytes which limits the process of cartilage tissue repair. Creation of nutrient gradients in in vitro cell culture, however, can provide a clue on zonal distributions of cells and glycosaminoglycan synthesis throughout the tissue engineered cartilage. We hypothesized that glucose gradient, in combination with growth factors, could induce differences in matrix distributions for articular cartilage regeneration. Chondrocytes were harvested from bovine cartilage and expanded in monolayers. First, either p0 or p2 chondrocytes were differentiated in serum-free chondrogenic medium containing different glucose concentrations supplemented with TGFβ3/dex or IGF-1under hypoxic or normoxic conditions for 7 days in monolayer. The results indicate that cellular metabolism, cell numbers and glycosaminoglycan (GAG) content increased with increase in glucose concentration in all conditions. Aggrecan (AGC) expression consistently increased with decreasing glucose concentration in both normoxic and hypoxic conditions. COL II and COL I expressions increased with increasing glucose concentration up to 5mmol/L. The expression of COMP increased with increasing glucose concentration under hypoxic conditions and interestingly showed an opposite trend under normoxic conditions. However, comparing the chondrogenic capacity of p0 and p2 cells in the different glucose concentrations did not show differences, but the potential of p2 cells was in general lower compared to p0. Hypoxia had stimulatory effects on matrix production compared to normoxia in both passages. Therefore, supplemented glucose concentration in monolayer could induce differences in matrix production, but the chondrogenic potential remained equal. Therefore, this information could be use to a create gradients through a tissue-engineered cartilage.
Segmentation of Malaria Parasite Based on Stained Blood Cells Detection
Authors: Abdul-Nasir Aimi Salihah , Mashor Mohd Yusoff , Mohamed Zeehaida
Published: July 2015

Malaria is characterized by its life-threatening and destructive capability through the cause of widespread sufferings, contributing to the increase in mortality rates throughout the various parts of the world. Since the needs for immediate and appropriate diagnosis of malaria are urgently needed, this paper proposes a procedure for colour image segmentation that has been utilized using the malaria images of P. vivax species. First, the malaria images are enhanced by using modified global contrast stretching technique. Then, cascaded moving k-means and fuzzy c-means clustering is applied in order to segment the infected cell from its blood cells background. In this study, a new colour component namely modified B-Y component is proposed as a modified version of the original B-Y component of C-Y colour model. By using modified B-Y component, the colour properties of the infected cell component will be utilized for stained object identification in malaria image. The proposed colour component is compared to intensity, R-Y and B-Y components for identifying the component of colour that provides the best segmentation result. Finally, median filter and region growing algorithms are applied for smoothing the segmented image and removing any unwanted regions from the image, respectively. The proposed segmentation method has been applied and tested on 100 malaria images. The results indicate that segmentation using the proposed modified B-Y component has produced the best segmentation results with segmentation accuracy, sensitivity and specificity values of 99.37%, 88.22% and 99.82%, respectively.
Inverse Kinematic Analysis of Three Link Mechanism for Fin Actuation of Fish Like Micro Device
Authors: Haq Mazhar Ul , Gang Zhao , Ahad Fazl E. , Ur Rehman Anees , Hussain Muhammad
Published: July 2015

In this paper, inverse kinematic analysis of a proposed three link mechanism of a bio-inspired micro scanning device towed underwater by a surface vessel to actuate its aileron fins for its depth control and for its stabilization against roll is performed. Mechanism is actuated by IPMC actuators. To speed up the design verification process, computer aided simulations are used to perform motion analysis of the proposed IPMC actuated mechanism through Pro/Mechanism tool. Inverse kinematic analysis is performed to find out the joint variables of the mechanism to realize fin actuation along desired path. Displacements, velocities and accelerations of the links constructing mechanism are found out to establish their interrelationship. Results are analysed for the study of mechanism efficacy and for sizing the IPMC actuators. This paper contributes to introduce a new approach of virtual prototyping using advanced simulation tools for analysis and design verification of IPMC actuated mechanisms for biomimetic applications before moving into functional prototype stage.
Dynamic Analysis of IPMC Actuated Fin of a Micro Fish Like Device
Authors: Haq Mazhar Ul , Gang Zhao , Ahad Fazl E. , Hussain Muhammad , Aftab S.M.
Published: July 2015

In this paper, a methodology is presented to perform dynamic analysis of structural linked mechanisms under true actuation cycle and force response of applied IPMC actuators. Dynamic analysis of a three link mechanism for fin actuation of a micro fish like device, towed by a surface vessel through tow cable, is performed through this methodology and same is applicable to other biomimetic robotic applications. Fluid (water) exerts a torque on IPMC actuated fin which is a function of fin's deflection and fluid flow velocity. Dynamic analysis is performed to assess the performance and efficacy of fin actuation mechanism under different loading conditions in terms of fin's deflection, velocity and acceleration. Actuation force is increased by increasing number of applied IPMC actuators of known actuation cycle and force generation response. Applied torque is determined by performing a numerical simulation of IPMC actuated fin against different flow velocities through two-way fluid structure interaction (FSI) approach. Numerical simulation is performed in ANSYS WORKBENCH to capture the complex hydrodynamic interactions between fin and fluid. Effect of increased actuation force against constant flow velocity (towing speed) and of increased flow velocity against constant actuation force are evaluated in terms of fin's deflection, velocity and acceleration. Finally, consequence of increasing the length of the link, connecting IPMC actuators and fin, are appraised for same actuation force and applied torque. Dynamic analysis is performed in Pro/ Mechanism, an advanced simulation tool. A technique of virtual prototyping through simulations is applied to access the performance of the fin actuation mechanism under true loading scenario before going into experimental phase, saving cost and time
Deflection Analysis of IPMC Actuated Fin of a Fish Like Micro Device
Authors: Haq Mazhar Ul , Gang Zhao , Waqas Hafiz Muhammad , Ur Rehman Anees , Aftab S.M.
Published: July 2015

IPMC is used as artificial muscle in bioinspired micro structures/devices due to its low voltage actuation, high bending deformation, rapid response and capability to be operated in aqueous environment. In this paper, deflection analysis of IPMC actuated fin of a micro fish like device is presented to find out angle of attacks generated by IPMC deflection under different voltages applied to it. A novel approach is presented to perform motion analysis of IPMC actuated mechanisms for biomimetic robots under true actuation presentation of the IPMC actuator. This paper also contributes to present velocity and acceleration of the actuator at different voltages. Finally, two different configurations of the fin actuation mechanism are characterized in terms of angle of attack produced by them under same actuation responses of an IPMC actuator. Deflection analysis is performed in Pro/ Mechanism, an advanced simulation tool. A technique of virtual prototyping through simulations is applied to access the performance of both configurations of the fin actuation mechanism under true scenario before going into manufacturing.
Control of the Cobalt Surface Layer Formation on Cemented Carbides
Authors: Pasquazzi Alan , Schubert Wolf Dieter , Weissenbacher Ronald
Published: July 2015

The formation of a surface layer of cobalt on cemented carbides which occurs on cooling during sintering is an often observed phenomenon which has been discussed in the recent literature. The presented work shows different factors which influence the formation of the layer and proposes factor-related mechanisms. For this purpose cemented carbide samples with different compositions, WC grain sizes and carbon contents were produced and studied. The results reveal that besides the cooling conditions also the variations in composition and microstructure of the material play an essential role for the formation of a surface layer.
New Biocomposites for Lightweight Structures and their Processes
Authors: Ouali Ahmed Amine , Rinberg Roman , Nendel Wolfgang , Kroll Lothar , Richter Anne , Spange Stefan , Siegel Carolin , Buchelt Beate , Wagenführ André
Published: July 2015

The development of new biocomposites and efficient manufacturing methods that are suitable for series processing is the purpose of the current sub-project C4 of the Excellence Cluster MERGE, sponsored by DFG (Deutsche Forschungsgemeinschaft). Two different types of materials are combined: bio-based thermoplastic polymers such as bio-polyethylenes or bio-polyamides and renewable reinforcing materials such as thin wood veneer or unidirectional flax fibers. To achieve a high-efficiency in terms of mass-production, reproducibility and flexibility, it is required to perform several steps in the realization of semi-finished and final products. The improvement of the adhesion at the interface of the components, the implementation of continuous processes, in order to increase energetically the yielding, and the final design, through several methods, for future potential applications are so many perspectives to achieve.
Interface Characterization of Hybrid Composite Extrusions
Authors: Reeb Andreas , Schulze Volker , Weidenmann Kay André
Published: July 2015

Through the development of new metal matrix composites, the specific strength and stiffness can be increased above the level of conventional light metal alloys and increase their potential for lightweight applications. The composite extrusion process is a promising manufacturing method for reinforced light metal extrusions. Particularly, the reinforcement with ceramic fibers can increase both the specific strength and stiffness which are essential for lightweight purposes. To exploit the full potential of the reinforcement, the interface of this MMC has to be optimized regarding the load transfer between matrix and fiber and therefore has to offer a strong bonding. In this contribution a hybrid composite is produced by using an Al2O3-fiber/AlMg0.2 composite wire which is embedded in an EN AW-6082 extrusion profile. Both the characterization of the interface and determination of the influence of processing and heat treatment are presented. For that purpose, the composites are characterized qualitatively by metallographic analysis and quantitatively by micro push-out testing of the ceramic fibers prior and after composite extrusion. To investigate the influence of additional heat treatment the state as fabricated, which equals a T4 state of the matrix material, as well as a T6 state with additional solution annealing and artificial ageing are compared. It was found that the extrusion process has a beneficial influence on the microstructure and the mechanical interface properties and therefore confirms applicability of composite extrusion for manufacturing of alumina reinforced profiles. The heat treatment however showed no significant influence on the embedded composite wire and its interface properties.
Influence of the Diamond Surface Termination on the Thermal Conductivity of Al/Diamond- and Ag/Diamond MMCs
Authors: Segl Jakob , Edtmaier Christian
Published: July 2015

MMCs consisting of diamonds and highly conductive metal matrices have been produced via gas pressure assisted liquid metal infiltration and their thermal properties have been investigated. Special attention was paid towards the diamond surface termination and its influence on the diamond-metal-interface and the resulting heat transport across this interface. Altering the diamond terminating surface layer can lead to a rather drastic increase in the thermal conductivity, rendering MMCs with pretreated diamonds double the thermal conductivity of the ones with as-received diamonds. The evolution of those terminating layers with different pretreatment conditions and their influence on the thermal conductivity of the resulting MMCs is rather complex and an ever-growing field of interest for diamond heat sink materials.The observed thermal properties of the MMCs produced in this study will be linked with the established diamond surface termination and will demonstrate the potential that lies within the method of diamond surface modification.
Influence of Reinforcement Geometry on the Very High-Cycle Fatigue Behavior of Aluminium-Matrix-Composites
Authors: Müller Alexandra , Weidner Anja , Biermann Horst
Published: July 2015

During technical operation, high performance materials are partially exposed to high frequency cyclic loading conditions. Furthermore, the small strains in the very high cycle fatigue (VHCF)-regime lead to accumulative damage which causes crack initiation related to an appropriate local deformation leading to final fatal fracture. At the same time, quite high requirements with regard to high number of cycles without any damage are demanded for many applications. Fields of application of these light-weight, but expensive materials, are e.g. in the automobile industry (e.g. engine blocks, cylinder heads, brakes).The fatigue behavior of Al-matrix composites (Al-MMCs) reinforced by alumina particles (15 vol.% Al2O3) or short fibers (20 vol.% Saffil), respectively, was already intensively studied in the LCF and HCF range. The present study is focusing on investigations in the very high cycle fatigue regime at stress amplitudes up to 140 MPa to reach fatigue life of about 1010 cycles. All experiments were carried out using an ultrasonic fatigue testing device under symmetric loading conditions (R=-1). Fatigue tests were accompanied by in situ thermography measurements to record the temperature of the whole specimen and to find “hot spots” indicating changes in microstructure and therefore the initiation or growth of cracks. Moreover, the resonant frequency as well as the damage parameter were evaluated to determine the beginning of damage. For a better understanding of the damage mechanism (matrix decohesion, matrix failure or failure of reinforcement) all fractured surfaces were investigated by scanning electron microscopy. The combination of these methods contributes to a better understanding of the underlying mechanism of damage in aluminum-matrix-composites.
Influence of Mg-PSZ Particle Size on the Fatigue Behaviour of a High Alloy Steel Matrix Composite
Authors: Droste Matthias , Biermann Horst
Published: July 2015

Metal Matrix Composites (MMC) based on a TRIP (TRansformation Induced Plasticity)- or TWIP (TWinning Induced Plasticity)-steel matrix reinforced with MgO-partially stabilized zirconia (Mg-PSZ) are an interesting research field as both components exhibit a deformation-induced or stress-assisted martensitic phase transformation and twinning, respectively. The present work deals with the fatigue characteristics of a reinforced CrMnNi-steel as a function of the ceramic particle size. Therefore, the particles were classified into three grades (grade 1: <10 μm; grade 2: 10-30 μm; grade 3: 30-50 μm) whereas the volume fraction concerning the composite material was kept constant at 10 vol.%. The composites were produced using the hot pressing technique. The tests were performed under total strain control in a range of 0.2% ≤ Δεt≤ 1.2%. The microstructure of fatigued specimens was examined using scanning electron microscopy.
Development and Characterisation of Phenolic Resin Moulding Materials for the Production of New Short Fibre-Reinforced C/C-SiC Composites
Authors: Nestler Daisy , Nier Natalia , Roder Kristina , Päßler Erik , Weißhuhn Julia , Todt Andreas , Würfel Hendryk , Kroll Lothar , Spange Stefan , Wielage Bernhard , Wagner Guntram
Published: July 2015

This article focuses on the development of phenolic resin moulding materials for the production of new carbon fibre-reinforced ceramic composite materials based on C/C-SiC by utilising the LSI (liquid silicon infiltration) production method. The production of these moulding materials is being accomplished by combining phenolic resin and carbon fibres with the addition of a few selected parts of processing aids, during which the influence of the used lubricants on the processability of the moulding materials is examined. The starting materials, microstructures and mechanical properties of the materials were characterised at every step of the entire process (CFRP and C/C composites) as well as the end of the whole production (C/C-SiC composites). During this investigation a link between the portions of the lubricant used, the forming of the porosity and the impact on the mechanical properties was discovered. In regards to the optimisation of the process the involved parties were able to determine an optimal lubricant ratio.
Development and Characterisation of Phenolic Resin Based Liquid Silicon Infiltrated SiC/SiC Composites with SiNx Fibre Coating
Authors: Mainzer Bernd , Frieß Martin , Roder Kristina , Nestler Daisy , Wett Daniel , Wöckel Lydia , Ebert Thomas , Wagner Guntram , Spange Stefan , Koch Dietmar
Published: July 2015

SiC/SiC ceramics consist of silicon carbide fibres embedded in a silicon carbide matrix. As an alternative to classic CVI and PIP routes, Liquid Silicon Infiltration (LSI) was chosen as a technique with short process times to obtain composites with low porosity. Silicon carbide composites show good thermal shock resistance, a low coefficient of thermal expansion and excellent physical and chemical stability at elevated temperatures and are therefore regarded as promising candidates for various applications in jet engines and in power engineering. To build up the matrix, different phenolic resin based carbon precursors were infiltrated in fibre preforms and thermally cured, pyrolysed and siliconized. The aim is to obtain a high carbon yield during pyrolysis and to control the pore morphology in a way that the following liquid silicon infiltration leads to a complete reaction of the carbon matrix with silicon to SiC. The siliconization behaviour and conversion into SiC in dependence of pore morphology and chosen precursor is analysed.At the same time a functional fibre coating has to be developed which protects the fibres from liquid silicon and simultaneously provides a weak fibre matrix bonding. A LPCVD-SiNx fibre coating has been chosen and is investigated in fibre composites especially in terms of protection and reactivity in different atmospheres during pyrolysis and siliconization.
Influence of Different Thawing Salts on the Material Properties of PA66GF30
Authors: Bauer Constantin , Magin Michael , Schalk Thomas
Published: July 2015

Rising weight and cost requirements in the automotive industry have led to an increasing substitution of metals by short-or endless-fiber reinforced thermoplastics. The use of thermoplastic matrices is necessary to meet the cycle time challenges which arise from large production quantities. The substituted components are often applied in the chassis or motor compartment, which means an exposition to environmental influences, e.g. moisture or thawing salts, during the entire operating lifetime. The degradation of the material properties of PA6GF30 due to a longtime exposition in DI (deionized) water, sodium-and calcium-chloride solutions is investigated and the fracture behavior examined by scanning electron microscopy analysis. Also, the fatigue properties were determined on a special test rig, which allows the spraying of the specimen with the different fluids during the mechanical cyclic testing.
Smart Material Composites Substitute Monolithic Structures
Authors: Frick Achim , Spadaro Marcel , Borm Michael
Published: July 2015

The present paper approaches possible advantages of hybrid constructions compared to monolithic design. Hybrid constructions represent multi-material composites where each of the materials employed are optimally utilized. Therefore, materials consumption decreases which leads to material, energy and cost efficiency and finally contributes to sustainability.The investigations targets on a possible substitution of a heavy iron casted pump housing by a metal-polymer hybrid light weight construction and on the achievable total mass reduction. Multi-material composites are prerequisite for lightweight design and promise a huge mass reduction potential.
Influence of the Impregnation Velocity on Impregnation Quality and Mechanical Properties of Vacuum Assisted Resin Transfer Moulding (VARTM) Materials
Authors: Archodoulaki Vasiliki Maria , Merola Massimiliano , Kastanis Dimitrios , Koch Thomas , Carlone Pierpaolo
Published: July 2015

Vacuum Assisted Resin Transfer Molding (VARTM) fabricated FRP laminates generally show significantly small void contents. The apparent difference in void content is generally attributed to the difference in the resin infusion driving force, i.e., vacuum versus injection pressure. In the present study, we contrast the influence of processing parameters on the impregnation quality of FRP laminates. Application of different vacuum pressures (500, 800 and ~103mbar) during VARTM results in different impregnation velocity due to different compaction levels produced. Composite laminates were realized using epoxy resin reinforced with carbon (CF) or glass continuous (GF) fibers. Two different textile architectures, namely unidirectional non-crimp fabrics (UD) and woven-mat (0/90), were used and various processing conditions were employed. Optical microscope observations revealed an unexpected trend relatively to the intra and inter bundle voids concentration with respect to the impregnation velocity, especially using UD-CF and UD-GF reinforcements and low impregnation rate. Tensile and three point bending tests highlighted the strong impact of fiber material and architecture on mechanical properties, whereas the presence of voids played a slight influence on the fiber dominated characteristics analyzed.
Residual Stresses in Intrinsic UD-CFRP-Steel-Laminates - Experimental Determination, Identification of Sources, Effects and Modification Approaches
Authors: Prussak Robert , Stefaniak Daniel , Hühne Christian , Sinapius Michael
Published: July 2015

This paper focuses on the reduction of process-related thermal residual stress in fiber metal laminates and its impact on the mechanical properties. Different modifications during fabrication of co-cure bonded steel/carbon epoxy composite hybrid structures were investigated. Specific examinations are conducted on UD-CFRP-Steel specimens, modifying temperature, pressure or using a thermal expansion clamp during manufacturing. The impact of these parameters is then measured on the deflection of asymmetrical specimens or due yield-strength measurements of symmetrical specimens. The tensile strength is recorded to investigate the effect of thermal residual stress on the mechanical properties. Impact tests are performed to determine the influence on resulting damage areas at specific impact energies. The experiments revealed that the investigated modifications during processing of UD-CFRP-Steel specimens can significantly lower the thermal residual stress and thereby improve the tensile strength.
Mechanical Requirements of Tailored Joining Technologies for Spring Elements in Multi-Material-Design
Authors: Busch Arne , Knorre Michael , Brandt Robert
Published: July 2015

The conflict of targets between mass reduction, strength and costs of a multi-material-design module is addressed by the example of a multi-material hybrid leaf spring. A rather simple model is defined such that one portion of the spring is made by glass fiber reinforced plastic (GFRP) and the other portion by a high strength spring steel.In a rather basic approach the leaf spring is exposed to uniaxial bending. The mass of this module is discussed as a function of the strength of the joint. Subsequently, the leaf spring is exposed to a multi-axial bending, e.g. as an effect of side loads. Hence, the relative strength of the anisotropic portion (GFRP) of the leaf spring is diminished whereas the strength of the isotropic portion (high strength spring steel) is only slightly affected. The mass of the module is discussed in the same way. It is shown up by this analysis that the conflict of targets can be solved in different ways by considering the specific strength of the joint.It is the target of this basic study to derive the mechanical requirement of strength of this tailored joint which has to be met by its design in order to solve the addressed conflict of targets in a preferable optimal way.
Influence of Material Properties on the Bond Strength of a Hybrid Part Consisting of Composite Sheet and Short-Fiber Thermoplastic
Authors: Moritzer Elmar , Budde Christopher
Published: July 2015

A significant advantage of continuous-fiber-reinforced thermoplastics (composite sheets) compared with sheet steel or aluminum is that the forming process can be integrated directly into the injection molding process. To do so, the composite sheet is heated by contact or infrared heating to a suitable temperature, then formed with the closing stroke of the injection molding tool, and subsequently back molded. In this way it is possible to achieve a high level of functional integration, because functional elements such as snap hooks and clips can be directly integrated as part of the molded component without the need for any additional process steps after finishing the part.This study investigates the influence of key material properties on the strength of the bond between such a composite sheet and the back-molded thermoplastic component, determined with a peel test.
Carbon Fiber Reinforced Composite – Toughness and Structural Integrity Enhancement by Integrating Surface Modified Steel Fibers
Authors: Lehmann Benjamin , Selvarayan Sathis Kumar , Ghomeshi Ravand , Gresser Götz T.
Published: July 2015

Carbon fiber reinforced plastic (CFRP) was integrated with steel fibers in order to improve the toughness and to enhance the structural integrity during crash. An epoxy system with internal mold release was chosen as the matrix system. The surface modification of steel fibers was done by sandblasting and twisting in order to improve the fiber-matrix adhesion through mechanical interlocking mechanism. The pull-out test of surface modified steel fiber doubled the adhesive strength. The steel fiber integration increased the maximum bending stress of the composites up to 20% whereas the elongation at break reduced to 2.3%. The energy dissipation factor of the steel fiber integrated CFRPs was also reduced compared to CFRPs without steel fiber. An increase in fracture toughness was observed for the CFRPs with steel fibers that amounts to 17 J.
Cost-Effective Microfibrillar Reinforced Composites for Lightweight Applications
Authors: Krooß Tim , Gurka Martin , Van der Schueren Lien , Ruys Luc , Fenske Stefan , Lenz Christopher
Published: July 2015

Microfibrillar reinforced composites (MFC) are self-reinforced polymer-polymer composites, consisting of a cold drawn (fibrillized) phase in an isotropic matrix. They are manufactured via melt blending of two immiscible polymers with different melting temperatures, followed by a subsequent cold drawing and thermal annealing step. The present study examines the manufacturing of composite material out of melt-spun microfibrillar reinforced filaments. Polypropylene (PP) and Polyethylene terephthalate (PET) were chosen as the low-melting matrix and the high-melting reinforcement phase, respectively.The filaments were woven to flat textile structures and processed to composites via hot pressing. They represent a bidirectional reinforced composite, comparable to other fiber reinforced polymers. To ensure optimized processing the influence of relevant parameters has been investigated with respect to mechanical properties of the MFC‑filaments and the derived composites. In addition, the morphology was visualized by SEM imaging after all manufacturing steps. An important observation was that the reinforcing fibrils are still intact after thermal processing, leading to a significant increase in mechanical properties of the resulting composites. Quasistatic tensile tests show more than 100 % higher modulus and more than 50 % higher strength of the only 20 wt-% reinforced PET‑PP composites compared to neat PP. The influence of the amount of PET reinforcement, the variation in processing conditions and composite layup were investigated. Additionally, an outlook on the melt-spinning of blends with Polyamide (PA) is given. In future work it is meant to show that a broad spectrum of tailored properties can easily be achieved by such polymer blends and composites outperforming existing homopolymers as well as thermoplastic composites like short glass‑fiber‑reinforced Polypropylene.The material cost reduction thanks to adding cheaper mass‑production polymers and the transfer onto conventional manufacturing lines is meant to ensure the feasibility of industrial production. The low density and excellent recycling options of these composites underline their potential for automotive and aircraft applications.
Spin-Blind-Riveting – A New Joining Technology for Hybrid Components
Authors: Podlesak Frank , Hälsig André , Mayr Peter
Published: July 2015

Hybrid components made of metals and fibre reinforced plastics (FRP) need new joining technologies which are suitable for all used materials. At the Technische Universität Chemnitz, Spin-Blind-Riveting (SBR) was developed, a hybrid process which combines blind-riveting, flow drilling and hole moulding. SBR is suitable for FRP, metals and has no need of predrilling. In this paper different material combinations made of aluminium, magnesium and FRP are joint by SBR. Mechanical tests show higher strength than conventional blind-riveting and macro sections show only slight damage to the FRP. It can be said that SBR is a high promising technology to join hybrid components.
Evaluation of Different Hybrid Material Systems and Systematic Analysis of their Physical Mechanisms in Terms of Fatigue
Authors: Hummelberger David , Kärger Luise , Henning Frank
Published: July 2015

Hybrid material systems are designed by the specific combination of different materials. As a result, expanded property profiles can be achieved, which would not be possible with monolithic material solutions. For lightweight, high strength and high rigidity, complex shaped structural components, which are used in the automotive industry and in aerospace, hybrid material systems offer an outstanding potential. A comprehensive understanding regarding the interaction of the individual components of the hybrid material is of great importance for a more efficient design of future structures. In this work, existing hybrid solutions for industrial applications and those, which are subject of current research, are analyzed and categorized first. Intrinsic and extrinsic material combinations are considered at different levels, ranging from hybrid laminates on shell level to complex hybrid structures on component level. Based on the situation analysis, different hybrid solutions are evaluated and compared considering the requirements of the automotive industry. Furthermore, the associated physical mechanisms which are responsible for the respective property profile are considered and explained systematically. The long-term objective of the work is to establish a methodology to derive the necessary physical mechanisms and, based on that, to derive optimal hybrid solutions for desired property profiles.
The Consequence on Structural Adhesive Bonding of Humid Thermoplastic Composites and Possibilities of Prevention
Authors: Bochtler Anselm Tobias , Knappe Christian , Dilger Klaus
Published: July 2015

A modern lightweight design with dissimilar materials such as metals in combination with fiber-reinforced polycaprolactam represents a possible lightweight variant in the automotive body shop. One of the issues arising from the use of polycaprolactam is its hygroscopy. The collected moisture evaporates out during the curing of the adhesive in the paint drying process and causes the adhesive to foam up. This leads to a decrease of the structural bonding strength. Many different factors, such as waterjet cutting processes, transportation and storage in undefined environmental conditions before the gluing process, as well as the flushing bath of the painting pretreatment, can contribute to the component humidity.Based on the common lap-shear test, this essay presents the influence of the substrate humidity on the bonding strength as well as possible pretreatment methods to avoid or decrease the negative influence of the substrate humidity. Using infrared radiation or atmosphere plasma localized at the bonding spot, the substrate begins to dry resulting in a bond with better bonding strength. For the future it is planned to test other options like laser substrate drying, adhesive modifications with regard to viscosity and moisture catcher enrichment.
Characterization of Metal Inserts Embedded in Carbon Fiber Reinforced Plastics
Authors: Gebhardt Johannes , Pottmeyer Florentin , Fleischer Jürgen , Weidenmann Kay André
Published: July 2015

The use of fiber-reinforced-plastics (FRP) contributes to an efficient implementation of lightweight design due to their outstanding specific mechanical properties. The RTM process offers great design freedom and allows the integration of functional elements during manufacturing. Embedded metal elements, so-called inserts, can be used to deal with the load transfer to structural parts. These elements have distinctive characteristics in comparison to other joining technologies. For example, detachable connections can be established with the help of inserts. Due to the fiber continuity not being interrupted and, subsequently, the FRP parts not having to be drilled, there is no local bearing stress. This paper aims at the characterization of metal inserts in FRP parts. The parts are manufactured using the RTM process with a specially adapted RTM mold with exchangeable cartridges for different insert geometries. The inserts are made of metal sheets with welded bushings and are embedded during preforming. The cured FRP specimens are tested under different load conditions to evaluate their suitability for various fields of application. Furthermore, the diameter and thickness of the metal sheet of the insert as well as the thickness of the FRP are varied to identify their influence on the failure behavior and load capacity under tensile loads.
Analyses of Boundary Conditions for Process Integration of Sensor Elements in Complex Fibre-Reinforced Thermoplastic Spacer Structures
Authors: Möbius Teresa , Krahl Michael , Helwig Martin , Adam Frank , Modler Niels , Starke Eric , Sauer Sebastian , Fischer Wolf Joachim
Published: July 2015

The application of hybrid yarns and their further processing to textile preforms enforce adapted manufacturing processes. Furthermore, a consolidation of cross-section varying parts requires an adapted mold and core system for a reproducible production process. Similarly, the application of hybrid yarns facilitates low consolidation pressures and thus favors the integration of electronic components in fibre-reinforced thermoplastic parts. In this paper, the analyses of the boundary conditions for a process integration of sensor elements in complex fibre-reinforced spacer structures are presented.
Laser Assisted Electrical Contacting in Multifunctional GF/PP Composites
Authors: Schilling Niels , Wiegand Niclas , Klotzbach Udo
Published: July 2015

The electrical contacting of an embedded sensoryarn in a unidirectional glass fiber polypropylene (GF/PP) composite realizedby laser processing was investigated. It was shown that compared to thecircular drilled hole the same electrical contacting quality can be achieved atan increased mechanical performance level.
Experimental and Numerical Studies on Integration Thermoplastic Composite Compatible Piezoelectric Ceramics for Actuatory Application of Cylindrical Hollow Structures
Authors: Weber Tony , Gude Maik , Kastner Tobias
Published: July 2015

Regarding the economical use of fiber-reinforced plastics (FRP) as a construction material for structural components whose additional value caused not only in their high specific mechanical properties. Due to the layerwise structure definition of continuous fiber reinforced composites the corresponding production technologies offers a high potential for integration of additional functional elements. Past efforts to the integration of functions in fiber-reinforced composites usual provide in front of a passive use of the piezoelectric effect (eg. structural-health monitoring). Through efficient and structurally defined using of piezoceramic actuators, the planar structure topology of cylindrical hollow FRP profiles can be actively influenced. Based on experimental studies on the definition of basic concepts for the integration of thermoplastic compatible piezoceramic modules (TPM) in fiber composite tubular segments, this paper deals with the understanding and performance capabilities of such actuarical hollow frp structures. The selective excitation and manipulation of the vibration behavior of such rotationally symmetric structures serves for generation of wave effects with radial translational characteristic. The performed experimental studies on the structural behavior of active piezo integral pipe segments are abstracted and compared by means of numerical simulations using multi-physical elements.
Integrative Manufacturing of Textile-Based Sensors for Spatially Resolved Structural Health Monitoring Tasks of Large-Scaled Composite Components
Authors: Haentzsche Eric , Mueller Ralf , Ruder Tristan , Nocke Andreas , Cherif Chokri
Published: July 2015

For the continuous and non-destructive structural health monitoring (SHM) of fiber reinforced plastics (FRP), a one-step integration of one-or two-dimensional strain sensors based on piezo-resistive carbon filament yarns (CFY) into textile reinforced structures of subsequent FRP components has been realized during textile-technological manufacturing processes. The two-dimensional alignment of the sensor layouts is realized by a special process-integrated warp yarn path manipulation (WPM). With suchlike manufactured semi-finished reinforcement structures, a functional model of a small wind turbine blade in glass-fiber thermoset composite design has been build up. Using the CFYs’ piezo-resistive effect, mechanical strains can be measured and visualized due to a correlative change of the carbon filaments resistance. Performing quasi-static load tests on the blade and additional test specimens, comprehensible results of the electro-mechanical behavior and spatially resolving capacity of different sensor integration lengths have been achieved. The performed tests demonstrate, that global and even local mechanical stresses within complex FRP components can be measured spatially resolved using the approach of textile technologically integrated textile sensors.