bluuebunny/crossref_metadata_2025 huggingface dataset:
Membranes of Chitosan and Collagen-Type 1 for Biomineralization/Ostheogenesis
Authors: Pacheco Ricardo B. , Tonoli Marina Salvarani , Beppu Marisa Masumi
Published: November 2013

The main objective of this work was to produce membranes of chitosan and collagen type I and check their ability to undergo “in vitro” calcification. The membranes of chitosan-collagen blends were characterized by TGA, infra-red spectroscopy and DSC. Samples of dense and porous membranes were immersed in solution SBF (Simulated Body Fluid) in order to verify their “in vitro” calcification. The membranes were observed by SEM. The production of chitosan-collagen membranes is possible, in dense and porous versions. We can conclude that the blend is less resistant to high temperatures, in comparison to pristine chitosan membranes shown in literature. Through the initial assays of calcification, we observe that it is possible to induce the calcium deposition on a chitosan-collagen membrane, as seen by SEM. Microscopy of fracture surfaces showed fibril structures, probably formed by collagen.
Biomimetics and Marine Materials in Drug Delivery and Tissue Engineering: From Natural Role Models to Bone Regeneration
Authors: Ben-Nissan Besim
Published: November 2013

During the last two decades learning from nature has given us new directions for the use of natural organic and inorganic skeletons, drug delivery devices, new medical treatment methods initiating unique designs and devices ranging from nanoto macro scale. These materials and designs have been instrumental to introduce the simplest remedies to vital problems in regenerative medicine, providing frameworks and highly accessible sources of osteopromotive analogues, naofibres, micro and macrospheres and mineralising proteins. This is exemplified by the biological effectiveness of marine structures such as corals and shells and sponge skeletons to house self-sustaining musculoskeletal tissues and to the promotion of bone formation by extracts of spongin and nacre seashells. Molecules pivotal to the regulation and guidance of bone morphogenesis and particularly the events in mineral metabolism and deposition similarly exist in the earliest marine organisms because they represent the first molecular components established for calcification, morphogenesis and wound healing. It emerges that bone morphogenic protein (BMP) molecules-the main cluster of bone growth factors for human bone morphogenesis-are secreted by endodermal cells into the developing skeleton. Signalling proteins, TGF and Wnt-prime targets in bone therapeutics-are present in early marine sponge development. Furthermore, ready-made organic and inorganic marine skeletons possess a habitat suitable for proliferating added mesenchymal stem cell populations and promoting clinically acceptable bone formation. In this paper we review the nature, morphology and extent of this association and use of these structures for bone grafts, drug delivery and extracts such as proteins for regenerative medicine. As an example, in human biology a study of matrix vesicles will teach us valuable lessons on how proteins are captured and coated; and how the vesicle is able to dock and fuse with their target. We will describe significant technological trends aimed at producing delivery vehicles using natural-origin soft and hard organized matter; fabricated into capsules and cell-delineated assemblies.Therole model for this specific biomimicry is the filtering microskeleton of Foraminifera. We will outline new selected strategies based on our and others works for the engineering of new bone, based on biomimicry themes using these bioceramics building blocks.
Nano-Hybrid-Composite Scaffolds from Substituted Apatite/Gelatin
Authors: Mostafa Amany A. , Ibrahim Doreya M. , Korowash Sara I. , Fahim Fawzia , Oudadesse Hassane
Published: November 2013

Precursors for the preparation of Si-CHA (silicon and carbonate substituted hydroxyl-apatite) were added in stoichiometric composition in amounts either 30 or 50 solid wt. % to a solution of gelatin to form hybrid nano-composite scaffolds (B(G/Si-CHA)). Temperature was maintained at 40°C and pH at 8 during the reaction. Glutaraldehyde was added to complete the cross-linking then washed. Thereafter, glycine was added to the product to get rid of any glutaraldehyde remnants. Both, 30 and 50% obtained scaffolds were compared with ones containing the same proportions from previously prepared nano powders of the Si-CHA named (C(G/Si-CHA)). The four types and a control one made of gelatin alone (G) were examined by X-ray diffraction (XRD), infrared spectroscopy (FTIR), transmission and scanning electron microscopy (TEM & SEM) and mercury porosimeter. In vitro study was carried out on the prepared scaffolds by immersing in simulated body fluid (SBF) solution for different periods between 1and 28 days. The change in the percentage of the different ions with time in the solutions was followed. Results of IR showed the reaction of the carboxylic groups of gelatin with the added ingredients giving a homogeneous distribution of the inorganic phase formed (Si-CHA). High porosity reaching 94% was achieved with macro and micro pores without the addition of a porogen material.
Preparation and Characterization of Collagen/Hydroxyapatite Microsphere Composite Scaffold for Bone Regeneration
Authors: Sanosh Kunjalukkal Padmanabhan , Gervaso Francesca , Sannino Alessandro , Licciulli Antonio
Published: November 2013

In the present work Collagen/Hydroxyapatite microsphere (Col/mHA) scaffold with a multiscale porosity was prepared. Col/mHA composite scaffold was prepared by freeze-drying/dehydrothermal crosslinking method. The HA microspheres (mHA) were obtained by spray drying of nanohydroxyapatite slurry prepared by precipitation technique. XRD analysis revealed that the microspheres were composed only of pure HA phase and EDS analysis revealed that Ca/P ratio was 1.69. The obtained microspheres had an average diameter 6 microns, specific surface area of 40 m2/g by BET analysis and BJH analysis shows meso porous structure having an average pore diameter 16nm. SEM analysis shows that the obtained Col/mHA scaffold had a macro porosity ranging from micron to 200 microns with meso porous mHA embedded in the collagen matrix.
Recent Progress in the Field of Multicomponent Biocompatible Nanostructured Films
Authors: Shtansky Dmitri V. , Levashov Evgeny A. , Batenina Irina V. , Gloushankova Natalia A. , Anisimova Natalia Yu. , Kiselevsky Mikhail V. , Reshetov Igor V.
Published: November 2013

Multicomponent bioactive nanostructured films (MuBiNaFs) with an excellent combination of chemical, mechanical, tribological, and biological properties were developed and deposited by sputtering of composite targets produced via the self-propagating high-temperature synthesis method. Reviewed substrate materials included Ti-, Ni-, and Co-based alloys, insoluble polymers, and deimmunized donors bones. Our results showed that the MuBiNaF deposition can be effectively combined with either a bulk material modification to improve its mechanical properties, or a surface modification to control surface roughness and blind porosity. Among other promising applications, the fabrication of hybrid materials incorporated with stem cells or medicine is mentioned.
Bio-Ceramics for the Next 25 Years: Challenges and Opportunities
Authors: Hench Larry L.
Published: November 2013

This paper examines challenges and opportunities for the field of bio-ceramics to achieve innovative solutions in two important areas of healthcare; regenerative medicine and personalized versus statistical-based diagnosis and therapy of individual patients. These opportunities are based upon use of new minimally invasive bio-photonics technology that can produce patient specific cell-based data to minimize costs, time and use of animals in developing and testing new bioactive ceramics. Changing the research culture is necessary to achieve significant improvements in the cost/benefit ratio of healthcare for aging populations. The approaches advocated in this paper have potential to achieve this cultural change.
In Vitro Evaluation of the Cytotoxicity of Some New Titanium Alloys
Authors: Bărbînţă Andreea Carmen , Earar Kamel , Crimu Carmen Iulia , Drăgan Lucia Anişoara , Munteanu Corneliu
Published: November 2013

Titanium alloys are widely used in medical applications, due to their good mechanical properties, high corrosion resistance and biocompatibility. The aim of this paper was to investigate the cytotoxicity of novel titanium alloys: Ti21Nb6Zr15Ta, Ti25Nb10Zr8Ta, Ti17Nb5Zr5Al, Ti7Nb7Zr2Al with fibroblast-like cells derived from human osteosarcoma cell line (HOS). The results were compared with that of conventional biomedical alloys, like Ti6Al7Nb and Ti6Al4V. In vitro citotoxicity of titanium alloys was evaluated by fluorescence microscopy and MTT colorimetric assay. The results showed that the materials analyzed had no cytotoxic effects on HOS fibroblast-like cells, permitting their attachment and proliferation. Also the new titanium alloys present a higher cell viability than that of the conventional alloys. As a consequence, the TiNbZrTa and TiNbZrAl alloys can be considered as potential candidates for biomedical applications.
The Micro CT Evaluation of Different Types of Matrices in Rats Bone Augumentation
Authors: Rusu Laura Cristina , Mănescu Adrian , Negrutiu Meda Lavinia , Sinescu Cosmin , Ardelean Simina , Hoinoiu Bogdan , Rominu Mihai
Published: November 2013

Introduction. The osteoconductive materials are very important in the bone regeneration procedures. The aim of this paper is to evaluate the interface between the old bone and the new regenerated one.Materials and methods. Ten rat femurs were used for this investigation. Under strict supervision, ten holes were drilled in the rat femurs and then filled with Bio-Oss® (Geistlich, Wolhusen, Switzerland). matrix. The samples were obtained after 3 month from the procedure and were investigated by MicroCT. A common Synchrotron Radiation X-Ray micro-CT experiment was performed at the SYRMEP Beamline of the ELETTRA Synchrotron Radiation Facility (Trieste, Italy). The 900 radiographic projections were acquired with a beam energy of 29 keV over 180° (0.2 degrees step) with a resolution of 9μm. A sample – detector distance of 16 cm was considered. The tomographic reconstruction was performed by means of the common filtered back-projection method. The 3D reconstructions were obtained at the University of Ancona using specific software, VGStudio Max.Results: The synchrotron offered 900 microCT files that were used to make the 3D reconstruction of the bone. After tomographic reconstruction, 3D renderings of obtained data may be made by electronically stacking up the slices. These 3D volumes may be also sectioned in arbitrary ways, zoomed and rotated in order to locate better the individual details. While the 2D slice images and 3D renderings are very useful for making qualitative observations of an internal concrete structure, the real benefit is the quantitative information that can be extracted from the 3D datasets.The reconstructions allow observing the normal rat bone, the new regenerated bone and also the rest of nonactivated matrix of Bio-Oss® (Geistlich, Wolhusen, Switzerland). The system permits to make measurements in order to quantify the volume of the new bone formation and also the status of the bone defect, in order to define the healing process.Conclusions: The MicroCT method proves to be an important imagistic tool for nondestructive evaluation of the interface between the new regenerated bone and the old one from the rat femurs. This method allows numerical quantification of the new regenerated bone and define the healing bone process.
The Aesthetic Effect of All-Ceramic Pressed Crowns According to the Thickness and Color of the Materials Used - An In Vitro Study
Authors: Drafta Sergiu , Popescu Adelina , Naicu Vlad
Published: November 2013

The final color of all-ceramic restorations may be influenced by the varying thickness of the dental abutment. Eighty A2 color (MO and LT) ceramic discs and eighty A3.5 color and four different thicknesses composite discs of were produced. The measurements were performed using the Vita Easyshade spectrophotometer. The results were statistically analyzed. Conclusion: There are no significant differences (perceived by the human eye) of the color parameters in the CIE L*a*b* system when comparing different combinations.
In Vitro Evaluation of New Dental Software for Shade Matching
Authors: Culic Bogdan , Prejmerean Vasile , Gasparik Cristina , Culic Carina , Dragos Cristian , Dudea Diana
Published: November 2013

In this study we evaluate a new computer software developed for determining tooth color parameters obtained from digital images taken in a general practice working conditions. In order to evaluate the accuracy of the program, we used as samples dental shade tabs. The tabs were measured using a dental spectrophotometer, and then photographed and measured using our program (Toodent). L, a, b values of the CIE Lab color space were obtained. The results were also automatically expressed in dental shade tab code. The results analysis was made by comparing the L, a, b values obtained by the program, with spectrophotometer ones taken from the same shade tab. A statistical indicator was created in order to evaluate the accuracy of the program. Further evaluation of the program shall be made, in order to be used in routine clinical color selection.
Transfemoral Fixation in Soft Tissue Cruciate Ligament Reconstructions – Composite Versus Polymeric Implant Analysis
Authors: Laptoiu Dan , Marinescu Rodica , Botezatu Iozefina
Published: November 2013

Different methods are available for ﬁxation on the femoral side of a quadruple soft tissue autograft in anterior cruciate ligament reconstruction and the best method is still to be found. There are also a large number of polymers in current practice, with a trend towards ceramic composites, required for better bone formation around the implant. If ceramic – polymer composites have better bioactive properties can be demonstrated only by long term in vivo follow up. Several methods of trans-femoral fixation are currently in use in our clinic – two of them being compared in this study: Rigidfix (Mitek DePuy Westwood, MA) and Biosteon (Stryker). First system produces a very stiff fixation using two implant pins made of poly-L-lactic acid (PLLA); the second technique is using a large composite (25% hydroxyapatite and 75% PLLA) suspension system with the mechanical advantage of achieving a “ press-fit” graft fixation in the tunnel. We prospectively follow our cases with clinical visits at 1, 3, 6 and 12 months – for research purposes, in a series of 20 cases (10 from each group) MRI (Siemens, 1,5 Tesla) were performed at same time intervals. Volume loss of the implant, tunnel enlargement, presence of osteolysis, ﬂuid lines, edema and postoperative pin replacement by bone tissue were evaluated. There was no edema or signs of inﬂammation around the bone tunnels at more than 24 months of folllow-up. Several of the Biosteon sites were surrounded by an area of increased signal on the fat-suppressed images. At 12 months, the femoral implants showed an average volume loss of 80% (±10%) P\0.05), respectively. At 3, 6, and 12 months volume losses range from 5 % (±2%), 29% (±19%) and 89% (±7%) for the composite implant. The femoral tunnel enlargement was less than 50% of the original bone tunnel volume after 12 months. Bone ingrowth was observed in all patients. Use of a composite ceramic – polymer bioabsorbable material (enhanced to form bone) will be easily incorporated by the body, retain strength for an adequate period of time, obviate the need for secondary procedures such as hardware removal, and facilitate revision surgery.
The Potential of Antibiotic Collagen Based Biocomposites for the Treatment of Bone Defects
Authors: Cristescu Ioan , Marina Lucian , Vilcioiu Daniel , Safta F. , Istodorescu M. , Stere A.
Published: November 2013

Antibiotic delivery systems used in the past have consisted primarily of impregnated cement beads that required routine removal once the antibiotic had eluded completely. With the development of collagen scaffolds that could be used to fill bony defects the antibiotic cold be delivered from the scaffold used to sustain local bone growth. Over the course of two years antibiotic loaded collagen scaffolds were used in the local treatment of 21patients suffering of complicated fractures including bone defects, infections or pseudoarthrosis, all of them of traumatic nature. At the time of the initial surgical debridement or at subsequent second look procedures once local tissue viability was observed the antibiotic loaded collagen scaffold was inserted in the tissue defect and never removed. Excellent results were obtained and the infection was brought under control by use of both surgical and antibiotic modalities. Bone grafting was used in 6 cases where the defects were extensive. Where there was less extensive bone destruction the scaffold was a good adjuvant in new bone formation. Use of antibiotic loaded collagen scaffolds is a reliable and effective means of local antibiotic delivery system combining both the new bone formation capacity of the scaffold to hold osteoblasts with the ability to deliver high doses of antibiotic in the local tissue environment and thus avoiding the systemic toxicity.
Biomechanics of Vertebroplasty: Effect of Cement Viscosity on Mechanical Behaviour
Authors: Craig Julie R.M. , Dunne Nicholas
Published: November 2013

Vertebroplasty is a minimally invasive surgical procedure, which requires efficacious percutaneous cement delivery via a cannulated needle to restore the strength and stiffness in osteoporotic vertebral bodies. Cement viscosity is understood to influence the injectability, cohesion and cement retention within the vertebral body. Altering the liquid to powder ratio modifies the viscosity of bone cement; however, the cement viscosity-response association between cement fill and augmentation of strength and stiffness is unknown. The aim of this study was to determine the relationship between viscosity, cement fill and the potential augmentation of strength and stiffness in an open pore foam structure that was representative of osteoporotic cancellous bone using an in vitro prophylactic vertebroplasty model. The results showed a strong linear correlation between compressive strength and stiffness augmentation with percentage cement fill, the extent of which was strongly dependent on the cement viscosity. Significant forces were required to ensure maximum delivery of the high viscosity cement using a proprietary screw-driven cement delivery technology. These forces could potentially exceed the normal human physical limit. Similar trends were observed when comparing the results from this study and previously reported cadaveric and animal based in vitro models.
Osteoconductive Bone Substitutes as Treatment of Benign Lytic Lesions
Authors: Dragosloveanu Serban , Cristea Stefan , Zaharie Dan
Published: November 2013

Benign lytic lesions represent a frequent pathology in our clinic. Regarding therapy, we approach these benign tumors through curettage and filling the defects with bone grafting or bone substitutes like hydroxyapatite crystals and tricalcium phosphate.We want to evaluate the efficiency of both bone grafts and bone substitutes regarding bone consolidation, osseointegration and time until absorption for tricalcium phosphate and hydroxyapatite crystals combination. We analyzed 14 patients treated in our clinic through curettage and defect filling during the last three years: 9 patients’ beneficiated from bone grafting and for the other 5 we used a hydroxyapatite and tricalcium phosphate combination from the same supplier. Diagnoses were bone cyst, non-ossifying fibroma and giant-cell tumor. Therapeutic method was linked with bone graft availability. Follow-up was 24 months through periodical x-ray controls in our clinic. Bone consolidation was satisfactory in all cases with no defect collapse. In conclusion, bone substitutes like combinations of hydroxyapatite crystals and tricalcium phosphate are a useful and safe method for surgical treatment of strictly benign lytic tumors.
Study of Bone Restoration Ca-Si-Zn Complex
Authors: Chung Ren Jei , Wang Huey Yuan , Chen Kai Shiang , Wu Huan Yu
Published: November 2013

In this research, the purpose is to carry out the in vitro study of the plasticity hybrid complex. The main components of the material are tricalcium silicate (C3S, Ca3SiO5) and collagen. In vitro studies, including cell toxicity test (MTT), flowcytometry detection and alkaline phosphatase test (ALP) were carried out to evaluate the biocompatibility of the materials and soaking mediums. Results showed that soaking mediums of different amounts of materials didn’t affect cell growth harmfully. Moreover, the soaking mediums would stimulate the osteoblast and trigger the biomineralization processes leading to higher secretion of ALP during cultivation.. The results in this research showed that the biocompatibility of our hybrid complex for future applications.
Synthesis and Characterization of an Experimental Zn-Hydroxyapatite Powders with Application in Dentistry
Authors: Prodan Doina , Moldovan Marioara , Prejmerean Cristina , Silaghi-Dumitrescu Laura , Boboia Stanca , Popescu Violeta , Pascalau Violeta , Molea Andreia , Diana Lazar , Perhaiţa Ioana
Published: November 2013

In the present study, Zn-hydroxyapatite (Zn-HA) was synthesized, the powder was thermally treated at different temperatures and then characterized. The Zn-HA powder was characterized mainly by FTIR and XRD, but have been performed investigations like SEM, BET and size distribution. The addition of ZnO in hydroxyapatite causes alleged interactions with the existing groups in HA, which amend the corresponding signals to these groups in the IR spectra. X-ray diffractograms for samples (untreated and heat-treated) have been recorded and microstructural parameters for the all samples have been calculated. The obtained average sizes of the crystallites and the network tensions support the idea that Zn-HA powders are nanostructured. The SEM images and size distributions for Zn-HA indicate a cluster of crystals with nanometer-scale of the population-base. Was determined the adsorption-desorption isotherms for Zn-HA powder at 100 o C and 800 o C. The dates obtained from the analysis of particle size distribution indicates for the Zn-HA powder an size distribution for granules in the range from 0.05 to 0.3μm
Radiographic Analysis of Bone Remodeling around Hydroxyapatite Coated Femoral Stems
Authors: Marinescu Rodica , Laptoiu Dan , Botezatu Iozefina
Published: November 2013

The study presented in the current paper was designed to investigate periprosthetic bone remodeling associated with two cementless HA coated stem models, ABG-II (Stryker) and Corail (DePuy), randomly implanted in 40 active patients at Colentina Clinical Hospital,Romania. Anteroposterior with neutral rotation and Lequesne profile radiographs of both hips were taken and several data were recorded: acetabular angle, rotation center of the hip, rotation center height with respect to the greater trochanter tip, femoral cortical thickness, cortico-medullary index at three areas (lesser trochanter (LT), 8 and 12 mm distal to LT), and osteoporosis severity according to the Singh index. The presence of osteolytic lesions in the proximal femur was assessed according to the scale proposed by Goetz in the radiographs obtained at the end of the follow-up (1 to 5 years). The radiological results showed that all stems were stable, and no evolutive radiolucent lines have been observed. We also have noticed minimal remodelling changes in 7 hips (36.61%), with minor cancellous bone densification mainly in zones 2 and 6, without cortical hypertrophy or osteoporosis. A decreased bone density in zones 1 and 7, secondary to stress-shielding, has been evident in 5 hips. Stem subsidence has been similar to that reported in literature with other hydroxyapatite coated designs.
Charge State of Silver Halide Colloids Determines the Antibacterial Activity in Amorphous Calcium Phosphate
Authors: Gross K. , Kalnina Daina , Stankeviciute Zivile , Nikolajeva Vizma
Published: November 2013

Removal of bacteria is important not only at implantation, but after long-term implant/prosthesis use. This requires strategies that employ different approaches for combating bacteria. Halides have the potential of an additional mechanism, and together with silver may provide a more powerful antibacterial strategy. Silver iodide was synthesized as colloids with a positive and negative charge and incorporated into an amorphous calcium phosphate (ACP) to provide a possible greater antibacterial action. Colloids were characterized by FTIR spectroscopy and the charge measured by zeta potential. Phase analysis by X-ray diffraction patterns confirmed the formation of b-AgI nanoparticles. Minimum inhibitory concentrations (MIC) for preventing the growth of Staphylococcus aureus andPseudomonas aeruginosa were lower for ACP containing negatively charged silver halides. Amorphous calcium phosphates with silver iodide exhibited good inhibition capacity. Solubility was determined by the increase in pH and the release of silver after 48 hours. The minimum bactericidal concentration (MBC) was also determined. This work has shown the effect of AgI charge in amorphous calcium phosphate for providing antibacterial action.
Nano Calcium Phosphate Powder Production through Chemical Agitation from Atlantic Deer Cowrie Shells (Cypraea cervus Linnaeus)
Authors: Gunduz Oguzhan , Sahin Yesim Muge , Agathopoulos Simeon , Agaogullari Duygu , Gokce Hasan , Kayali E.S. , Aktas Cenk , Ben-Nissan Besim , Oktar F.N.
Published: November 2013

The process is a simple chemical method and aims to produce nano-structured calcium phosphate powders from natural sources, for biomedical applications. For this purpose, Atlantic Deer Cowrie (ADC) shells (Cypraea cervus Linnaeus, 1771) were collected from a local gift store in Istanbul. The empty shells were cleaned and crushed then were ball milled and sieved under 100µm. The raw powders were suspended on a hotplate stirrer for a simple chemical agitation. The temperature was kept at 80°C for 15 min. and then appropriate amount of H3PO4 was added by titration into the prepared solution to form calcium phosphate precursors. The solution was stirred on a hotplate for 8 hours then dried at 100°C for 24 hours. Afterwards the resulting dried sediments were collected and heat treated between 400-800°C for 4 hours, dependent on the required specific calcium phosphate phase. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were carried out for identifying various hydroxyapatite (HA), tricalcium phosphate (TCP) and other calcium phosphate phases. Various particle sizes ranging from nano to micron, are obtained depending on the chemistry used and the processing technique applied during the production. A range of calcium phosphate phases can be obtained from ADC shells, by using a simple and economic conversion method. Proper cleaning methods developed and appropriate preparation techniques will enable us to use these nano calcium phosphate powders in orthopedic and dental applications.
Failure Mechanisms of an AISI 4135 Steel Submitted to the Disk Pressure Test under Helium and Hydrogen Gas
Authors: Ardon Kevin , Gasperini Monique , Charles Yann , Furtado Jader
Published: November 2013

The present work focuses on the experimental multi-scale characterization of fracture of an AISI 4135 steel by using the Disk Pressure Test (DPT). In order to precise the specific features of hydrogen embrittlement, comparison was made between disks burst under helium and hydrogen gas. SEM - EBSD analysis of disks samples before and after the test allowed to analyze and to compare the main microstructural mechanisms of the failure process. The location of the main crack initiation was consistent with Finite Element (FE) simulations of the DPT.
Mechanical Behavior of Steel-Chips-Reinforced Concrete
Authors: Djebali Said , Bouafia Youcef , Larbi Said , Bilek Ali
Published: November 2013

This work is a part of an industrial waste development program. It is devoted to the study of recyclability of chips resulting from the machining of steel parts as reinforcement for concrete. We are particularly interested in this study in the rheological behavior of chips reinforced fresh concrete and its mechanical behavior at young age. The evaluation of the workability indicates that the sand over gravel optimal ratios (S/G), corresponding to the composite minimum flow time, are S/G = 0.8 and S/G = 1. The study of the chips content (W) influence on the workability of the concrete shows that the flow time and the optimal ratio S/G increase with W. Mechanical characterization tests (direct tension, compression, bending and splitting) show that mechanical properties of chips reinforced concrete are comparable to those of the two selected reference concretes (concrete reinforced with conventional fibers: EUROSTEEL fibers corrugated and DRAMIX fibers). Chips provide to control concrete a significant increase in strength and some ductility in the post-failure behavior of the composite. Recycling chips as reinforcement for concrete could be thus favorably considered.
Influence of the Microstructure near the Interface on the Fatigue Life of Explosively Welded (Carbon Steel)/Zr Clads
Authors: Prażmowski M. , Paul Henryk , Rozumek Dariusz , Marcisz Ewa
Published: November 2013

The paper presents joint zone microstructure and the test results obtained for fatigue cracks in zirconium-steel bimetal under bending. The materials were joined with explosive welding technology, and special attention was paid to characteristics of the joint zone.
Taguchi Optimization of Process Parameters for Forming Time in Incremental Sheet Forming Process
Authors: Liu Zhao Bing , Li Yan Le , Daniel W.J.T. Bill , Meehan Paul
Published: November 2013

ncremental sheet forming (ISF) is a new promising technology due to its flexibility and low-cost tooling properties compared with conventional forming processes. However, it is only suitable for small-batch production because of its incremental feature inducing relative long forming time. Presently, widespread usage of the process is restricted by a lack of predictive understanding of the process due to its complexity. In this paper, the aspect of forming time is studied by investigating the effects of four distinctive process parameters (step over, feed rate, sheet thickness and tool diameter). An effective analysis tool, Taguchi method together with design of experiment (DOE) and analysis of variance (ANVOA) is utilized to study the effects of the four process parameters on forming time and further to optimize parameter combinations in order to minimize forming time. Using these techniques, experimental results show that the step over of spiral tool path is the most important process parameter affecting forming time followed by feed rate. Sheet thickness and tool diameter have little effect on forming time. The comparison between the prediction of optimized parameter combination and the confirmation test result has further demonstrated the effectiveness of the proposed method. It is worth noting that the results of this study will indicate a further direction on how to optimize process parameters to find a balance between forming efficiency (forming time) and forming quality (forming accuracy and surface roughness).
An Experimental Investigation of Edge Strain and Bow in Roll Forming a V-Section
Authors: Abeyrathna Buddhika , Rolfe Bernard F. , Hodgson Peter , Weiss Matthias
Published: November 2013

V-sections were roll formed from two grades of steel, and the strain on the top and bottom of the strip near the edge was measured using electrical resistance strain gauges. The channels were bent to a radius of 2 and 15 mm along the centerline. The steel strips were of mild and dual phase steel of yield strength 367 MPa and 597 MPa respectively. The longitudinal bow was measured using a 3-dimensional scanning system. The strain measurements were analysed to determine bending and mid-surface strains at the edge during forming.
The peak longitudinal edge strain increased with material yield strength for both profile radii. For the 15 mm radius, the bow was larger in the dual phase steel than in the mild steel. For the 2 mm profile radius, the bow was smaller compared with the 15 mm profile radius and it was similar for both steels. It was observed that the difference between the peak longitudinal edge strain and yield strength to Youngs modulus ratio of the material is an important factor in determining longitudinal bow.
Investigation and Comparison of Heat Transfers Analysis Used in Commercial FEM for Metal Forming
Authors: Flitta Isaac , Hatzenbichler Thomas , Buchmayr Bruno
Published: November 2013

During an Aluminium extrusion process, the extrusion parameters, i.e. friction, heat transfer, etc. are significantly influence by the temperature gradients produced in the billet during transfer to the container and after upsetting the container. The heat transfer at the tool/billet interface governs the temperature profile throughout the billet and tools during extrusion and consequently has a critical influence on the results. Although FEM technique offers great potential, care must be taken when applying the analysis to the hot extrusion of rate sensitive alloys. The most useful approach of an FEM simulation would thus be to include both the tooling and the billet in the calculation as discretised meshes. Because of the occurrence of the conductive and convective heat transfer, the deformation during hot extrusion is not adiabatic and estimation of the temperature increase is alloy dependent. The aim of this paper is to investigate and to compare how commercial FEM codes assign and deal with the heat transfer parameter at the tool/material interface. Three commercial FEM codes were investigated and compared; Simufact, Deform and Forge. The usefulness and limitation when using commercial FEM codes are discussed. Methods to assess difficulty of comparison are presented. The work illustrates the essentials of numerical analysis in the comprehension of the thermo-mechanical events occurring during large deformation. Results are presented for velocity distribution and temperature evolution in both materials and tools. It is shown that the heat transfer parameter to be extremely sensitive when attempting to simulate the hot deformation. Moreover, the accuracy of the results does not only depended on the geometric definition of the tooling and material data but also the governing boundary conditions between the material and tooling.
The Influence of Mechanical Mold Vibration on Temperature Distribution and Physical Properties of Al-11.8%Si Matrix Composites
Authors: Sayuti M. , Sulaiman S. , Baharudin B.T.H.T. , Ariffin M.K.A.
Published: November 2013

Mechanical vibration was introduced into the Aluminum alloy matrix composite during solidification process. The cooling curves of composite with mechanical vibration were measured and compared without mechanical vibration. The thermal conductivity and thermal diffusivity properties of the Al/TiC composite were investigated. The result indicated that the mechanical vibration reduces the temperature inhomogeneity of melt. The density of the composite with 10.2, 12, 15Hz and 16 Hz of mechanical vibration improved apparently compared with the composite without mechanical vibration. The thermal conductivity and thermal diffusivity properties of composites with mechanical vibration are also both improved significanly.
Comparison of Ironing in Warm and Hydromechanical Deep Drawing of Low Carbon Steel
Authors: Singh Swadesh Kumar , Gupta Amit Kumar
Published: November 2013

Deep drawing involves conversion of flat thin sheet metal blanks into parts of desired shape. In the present investigation, the process parameters of warm forming are compared with those of Hydromechanical deep drawing. Warm deep drawing process of circular blanks in Ironing stage is investigated using a 20 T hydraulic press. Hydro-mechanical deep drawing is a process for producing cup shaped components with the assistance of a pressurized fluid. There is an increase in the drawability of low Carbon steel by increasing the oil gap (gap between punch and die) but to make exactly cylindrical shape, the cup is subjected to ironing in the later part of drawing operation. Thickness distribution which describes the quality of the drawn cup is compared in both warm and Hydromechanical deep drawing using experiments and finite element simulations. Keywords- Warm forming,Hydromechanical, deep drawing, Drawability.
Investigation on Failure Limit of the Perforated Sheet for Truss PCMs in Multiple Pin Stretch Forming
Authors: Kim Sang Woo
Published: November 2013

Periodic cellular metals (PCMs) based on lattice truss structure have been developed for a wide range of potential applications with their lightweight and multi-functionality. Although divers methods to fabricate truss PCMs, such as investment casting, perforation-bending, and extrusion-EDM, have been reported, the processes have been limited to fabricate flat plates. The paper proposes a new method, multiple pin stretch forming, to fabricate the truss PCM with various cross-sectional shapes. The process has some advantages to fabricate the truss architecture with locally different height and reduce the waste of material during perforation process compared with conventional processes. However, since a 3-D truss structure is built up by tensile deformation of truss members in the process, it is important to design the geometry of precursor sheet to avoid unexpected fracture and make full use of elongation of a given material. The paper focused on the design of precursor sheet through the investigation on failure limit in multiple pin stretch forming. The forming failure were predicted by FE simulations combined with a ductile fracture criterion for various geometrical conditions, and a forming failure diagram was constructed and verified with experiments. And finally, pyramidal truss PCMs with flat and stepped cross section were fabricated successfully without any defects.
Effect of Temperature on Mechanical Behaviour of High Manganese TWIP Steel
Authors: Shterner Vadim , Timokhina Ilana , Beladi Hossein , Hodgson Peter
Published: November 2013

The aim of the present study was to investigate the role of deformation temperature on the active deformation mechanisms in a 0.6C-18Mn-1.5Al (wt%) TWIP steel. The tensile testing was performed at different temperatures, ranging from ambient to 400°C at a constant strain rate of 10-3 s-1. The microstructure characterization was carried out using a scanning electron microscopy. The deformation temperature revealed a significant effect on the active deformation mechanisms (i.e. slip versus twinning), resulting in different microstructure evolution and mechanical properties. At the room temperature, the mechanical twinning was the dominant deformation mechanism, enhancing both the strength and ductility. Dynamic strain aging (DSA) effect was observed at different deformation temperatures, though it was more pronounced at higher temperatures. The volume fraction of deformation twins significantly reduced with an increase in the deformation temperature, deteriorating the mechanical behavior. There was a transition temperature (~300°C), above which the mechanical twinning was hardly observed in the microstructure even at fracture, resulting in low ductility and strength. The current observation can be explained through the change in the stacking fault energy with the deformation temperature.
Analysis of Automated G-Clip Machine Processes and Substation Process with Simulation by Using CAD Software
Authors: Ariffin M.K.A. , Kamaluddin Rohaya , Tang S.H. , Mohamed Saiful Bahri
Published: November 2013

The paper presents the work of analysis of Automated G-clip Paperclip machine of using Solidworks Simulation and a comparison between results of each analysis in cutting process using design of experiment (DOE) and followed by design verification of simulating the cutting process after design changes. It emphasizes on the analysis of process and additional substation process to overcomes current machining problem. The current problem is occurred at the cutting station, which lead to poor quality product. There is two-design stage, which is preliminary of design of experiments conducted in order to fulfill the design validity and design verification. Application of longitudinal cyclic transfer system in feeding with pre-straightener substation is implied for comprehensive feeding of the wire with 1.3 mm diameter in 2 second. Forming dies with stepper motor controller give the precise positioning and repeatability of movement since good stepper motors have an accuracy between 3 5% of a step and this error is non-cumulative from one step to the next. By incorporating the new station in simulation procedure for this machine, it shows that the product quality is improved.
Niobium Containing Advanced High Strength Steels for Automotive Applications – Processing, Microstructure, and Properties
Authors: Bhattacharya Debanshu
Published: November 2013

Two major drivers for the use of advanced steels in the automotive industry are fuel efficiency and increased safety performance. Fuel efficiency is mainly a function of weight of steel parts, which in turn, is controlled by gauge and design. Safety is determined by the energy absorbing capacity of the steel used to make the part. All of these factors are incentives for the automobile manufacturers to use Advanced High Strength Steels (AHSS) to replace the conventional steels used to manufacture automotive parts in the past. AHSS is a general term used to describe various families of steels. The most common AHSS is the dual-phase steel that consists of a ferrite-martensite microstructure. These steels are characterized by high strength, good ductility, low tensile to yield strength ratio and high bake-hardenability. Another class of AHSS is the complex-phase or multi-phase steel which has a complex microstructure consisting of various phase constituents and a high yield to tensile strength ratio. Transformation Induced Plasticity (TRIP) steels is another class of AHSS steels finding interest among the U.S. automakers. These steels consist of a ferrite-bainite microstructure with significant amount of retained austenite phase and show the highest combination of strength and elongation, so far, among the AHSS in use. High level of energy absorbing capacity combined with a sustained level of high n value up to the limit of uniform elongation as well as high bake hardenability make these steels particularly attractive for safety critical parts and parts needing complex forming. A relatively new class of AHSS is the Quenching and Partitioning (Q&P) steels. These steels seem to offer higher ductility than the dual-phase steels of similar strengths or similar ductility as the TRIP steels at higher strengths. Finally, martensitic steels with very high strengths are also in use for certain parts. The most recent initiative in the area of AHSS is the so-called 3rd Generation AHSS. These steels are designed to fill the region between the dual-phase/TRIP and the Twin Induced Plasticity (TWIP) steels with very high ductility at strength levels comparable to the conventional AHSS. Enhanced Q&P steels may be one method to achieve this target. Other ideas include TRIP assisted dual phase steels, high manganese steels and higher carbon TRIP type steels. In this paper, some of the above families of advanced high strength steels for the automotive industry will be discussed with particular emphasis on the role of niobium.
Mechanism of Variable Helix Tools in Suppressing Chatter Using Process Damping for Machining Titanium Alloys at Low Cutting Speed
Authors: Shaharun Muhammad Adib , Yusoff Ahmad Razlan , Reza Mohammad S.
Published: November 2013

Titanium is difficult-to-cut materials due to its poor machinability and thermal conductivity when machining at high cutting speed. To overcome this machining titanium alloy problem, this study in interaction between machining structural system and the cutting process are very important. One of the main problems in the cutting process is chatter vibration. Due to chatter problem, the mechanism to suppress chatter named, process damping is a useful method can be manipulated to improve the limited productivity of titanium machining at low speed machining in milling process. In the present study, experiment are conducted to evaluate and study the process damping mechanism in milling using different types of variable tools geometries. These tools are variable he-lix/uniform pitch, variable pitch/uniform helix and variable helix and pitch and uniform helix/pitch. The result showed that the variable helix and pitch tools is very significantly improve process damping performance in machining titanium alloy compare to traditional of regular tools and other irregular tools.
Tool Wear and Surface Roughness when Machining AlSi/AlN Metal Matrix Composite Using Uncoated Carbide Cutting Tool
Authors: Said M.S. , Ghani J.A. , Che Haron Che Hassan , Yusoff Shahrizan , Selamat Mohd Asri , Othman R.
Published: November 2013

Aluminium silicon alloy (AlSic) matrix composite reinforced with aluminium nitride (AlN) particle is a new generation material for automotive and aerospace application. This material has low density, light weight, high strength, high hardness and stiffness. Metal Matrix Composit (MMC) material is one of the advanced materials which have good future prospects. This paper presents the study of tool wear and surface roughness investigation when milling AlSi/AlN Metal Matrix Composite using uncoated carbide cutting tool. The volume of AlN reinforced particle was 10%. The milling process was carried out under dry cutting condition. The uncoated carbide insert parameters used were cutting speed of (250-750 m/min), while feed rate and depth of cut were kept constant at 0.15 mm/tooth of 0.3mm respectively. The Sometech SV-35 video microscope system and Mitutoyo surface roughness tester were used for tool wear measurements and surface roughness respectively. The results revealed that the tool wear increases with cutting speed (450 m/min). While at high cutting speed, the surface finish improves. It was found that the cutting speed of 750m/min was optimum condition for obtaining smooth finish and longer tool life. Keywords: AlSi/AlN Metal Matrix Composite milling process, tool wear, and surface roughness, uncoated cemented carbide tool
Analytical Chatter Stability Prediction for Irregular Types of Milling Tools
Authors: Yusoff Ahmad Razlan , Mansor Muhammad Hatifi , Hussain Hazami Che , Abidin Muhammad Azwan Zainol
Published: November 2013

High productivity, low cost and high profits in machining processes is important aspects in aerospace, automotive and tool/die metal manufacturing industries. However, the dynamic deflection of tool and work piece systems generates unstable cutting forces when machining with high material removal rate. The main focus of this paper is the study of variable tool geometries effect on chatter stability. A semi discretization method (SDM) was utilized to predict numerical chatter using variable helix, pitch and variable helix and pitch tools effect at high radial immersion. The results showed that variable helix and variable pitch milling tools exhibit better unstable behavior at 25 percent radial immersion.