Papers by Keyword: Radiography

Abstract: Dissimilar welding of 3mm thickness of AISI 304L austenitic stainless steel plate and AISI 430 ferritic stainless steel plates were performed by Tungsten Inert Gas welding without any filler material by using argon as shielding gas. Welding is carried out according to set of combinations of welding parameters such as welding current (levels of 135,140,145 Ampere), welding speed (levels of 105, 110, 115 mm/min) and shielding gas flow rate (of levels 5,10,15 Litre/min) obtained through Taguchi L9 orthogonal approach for maximizing the ultimate tensile strength by using MiniTab software . Radiography test was performed to know the soundness of the welds. Tensile specimens are fabricated as per ASTM E8 standard for tensile testing. Microstructural observations of the weld are performed. Correlations have been obtained to know the effect of welding speed, welding current and shielding gas flow rate on tensile strength and an optimum level of parameter is obtained at welding current of 145 Ampere, welding speed of 115 mm/min and shielding gas flow rate of 5 Litre/min.

Abstract: 3D imaging techniques have an enormous potential to understand the microstructure, its evolution, and its link to mechanical, thermal, and transport properties. In this conference paper we report the use of a powerful, yet not so wide-spread, set of X-ray techniques based on refraction effects. X-ray refraction allows determining internal specific surface (surface per unit volume) in a non-destructive fashion, position and orientation sensitive, and with a nanometric detectability. We demonstrate showcases of ceramics and composite materials, where microstructural parameters could be achieved in a way unrivalled even by high-resolution techniques such as electron microscopy or computed tomography. We present in situ analysis of the damage evolution in an Al/Al₂O₃ metal matrix composite during tensile load and the identification of void formation (different kinds of defects, particularly unsintered powder hidden in pores, and small inhomogeneity’s like cracks) in Ti64 parts produced by selective laser melting using synchrotron X-ray refraction radiography and tomography.

Abstract: Despite efforts to maintain quality during the construction of reinforced concrete structures, it is relatively common for improper reinforcement to be used, contradicting the project, which can lead to serious structural defects. It is then up to non-destructive testing methods to prove these defects. The key is the choice of the appropriate method and equipment, both in terms of achieving the necessary results and the possibility of their documentation. In recent years, there has been a significant progress in the development of non-destructive methods for the diagnosis of reinforcement and modernization of the technologies used so far, especially in the field of GPR and electromagnetic methods. At the same time, however, for a number of reasons, major limitations appear in the area of a conventional method of radiography. This contribution focuses on the current state of the problem, and it demonstrates the applicability of individual methods and their limitations given by their physical principles and technical solutions on a set of practical examples.

Abstract: Possibilities of non-destructive testing (NDT) methods to assess the quality of permanent joints of powder metal parts were evaluated. Antifriction bushing-bushing couples used in transport braking systems were investigated. The parts made of bronze graphite were crimped by pulsed magnetic deformation by means of electromagnetic equipment with a maximum discharge energy of 30 kJ. The gap between joint parts in the couples was assessed by ultrasonic and radiographic methods. A standard ultrasonic flaw detector Krautkramer USM-25 with an Olympus 4MHz dual-element echo transducer and an industrial x-ray apparatus YXLON EVO 200D were used, correspondingly. In first trial, both methods were equally sensitive to tight and weak connection of joints.

Abstract: Hip fractures/arthrosis were, still are and will be a challenge for the orthopedic surgeon. In this paper we conducted a case study on a rod used for hip replacement due to coxartrosis. The implant was used for hip replacement for NC patient aged 82 years. After twelve months the patient returns for the ablation of osteosynthesis material. Clinical and strengthen the fracture hip is found radiologic hypertrophic and degradation plaque. It was used a rod implant, on which were made following investigations in order to establish the causes that led to the fracture, namely: determining the chemical composition through spectral analysis, analysis macrostructural in stereo, microstructural analysis optical microscope metallographic respectively analysis fractogr aphic electron microscope streak. Complex analysis of the fracture surfaces of the hip prosthesis has led to the ultimate conclusion that the material has been made the hip prosthesis is inadequate chemical purity satisfactory embedding, which has led to breakage within an area of non-homogeneous structure.

Abstract: Foreign body materials enter human body through ingestion, insertion, or deposited by injury and may migrate from the entry site causing inflammation, abscess formation or undergo distant embolization. The aim of this study was to observe the degradation process of iron-based foreign body materials in different site of implantation through radiography approach. Forty two adult male ddy mice were used and iron-based implants were inserted into nape area, subcutaneously and into right femoral muscle using trocar, aseptically. The implants consisted of iron, chromium(Cr)-coated iron and stainless steel surgical wire (SS316L). Serial radiography was performed at day-1, 4 and 14 after implantation. The gray value of material density were then measured at 4 points : 2 points on both end and 2 points on the middle of the implants by using plot profile module in ImageJ® software. Results showed that the radiodensity of the implants from each group in both implantation site was increased at day-4 and materials’ radiodensity implanted subcutaneously showed higher gray value especially at peri-implant site along the side of the implant than those which implanted intramuscularly. Discussion on the degradation process and radiographic measurement is detailed in the manuscript.

Abstract: The heart function suppression during a long-term anestesia should be considered in implant placement surgery. The aim of this study is to determine the effect of propofol and isoflurane combination as a long-term anesthesia on the heart size using radiography vertebrae heart size (VHS) method. Rabbits were injected by propofol 12.5 mg/kg body weight intravenously as an induction and inhaled by 1.0 ml/minutes rate ofisoflurane in facemasked for next 12 hours. Thorax cardiogram in right lateral (RL) and dorsoventral (DV) view were obtained and compared according to duration of anesthesia at 0 hr, 4 hrs, 8 hrs, and 12 hrs. The result showed that heart size on RL view are 7.67±0.50v, 6.67±0.16v, 7±0.00v, and 7.53±0.23v, respectively, while the values on DV view are 7.33±0.23v, 7.06±0.30v, 7±0.2v, and 7.33±0.35v, respectively. The heart size on RL view was decreased after 4 hrs and increased after at 8 to 12hrs significantly (P<0.05) compared to DV view. As the conclusion, propofol and isoflurane combination as a long-term anesthesia had minimal effect on heart size and is a good candidate for long-term biomaterial implant placement procedures.

Abstract: The aim of this study is to determine constitutive constants for elasto-plastic material model with damage for single trabecula based on the indirect simulation of micromechanical testing and its verification at macro level using compression test of the cylindrical sample of the trabecular tissue. Three-point bending test of isolated trabeculae was performed in a shielding box and deflection of the sample was acquired using X-ray microradiography. Measured values (displacements of markers) were used for indirect identification of the material model for single trabecula using finite element (FE) method. The bending test was simulated and results were fitted to experimentally obtained values and the appropriate set of material constants was determined. To verify the applicability of the identified material model the compression test of the complex sample was carried out. Cylindrical sample was incrementally loaded and each loading state was captured using the micro-computed tomography. Material model identified from three-point bending test was applied to the model of complex sample and the simulation of the compression test was performed.

Abstract: Nondestructive testing (NDT) is an important tool in the world of industry. Among different NDT methods, radiography plays a very interesting role both in industry and medicine. Medical and industrial uses of X and gamma rays were recognized since more than 1 century ago. One of the interesting uses of radiography is in archeological and art applications. In this research, radiography was utilized for identification of a damaged art-historical material. The subject is a brass tray belonging to Iran cultural heritage with an estimated age of about 3500 years. The tray was found in Lorestan province and referred to as “Lorestan bonze”. The object was damaged seriously due to heavy corrosion attack. Therefore recognition of the object was a major problem. Normal radiography method can help for object determination, but it suffers some major drawbacks related to contrast and thickness measurement. Image processing technique and a precise thickness measurement method were added to digitized radiographs. A precise radiographic thickness method was introduced and used before for the pipeline radiography. For digital image processing, Canny edge detection method and Gaussian filter were used. Radiography image obtained from this work showed a very clear picture of the original trace of hammered design. These results showed that a combination of radiography, image processing techniques and consideration of physical principles of radiation interaction with materials can produce a very clear image which can be used effectively for hte detail analysis of cultural heritages.

Abstract: Wrought aluminium alloys are prone to hot tearing when cast into near-net shapes. This problem can be overcome by the novel casting technique of rheo-processing combined with high pressure die casting. An industrial engine mounting bracket is produced by rheo-process commercial 7075 with the patented CSIR-RCS and subsequent high pressure die casting. Section thickness changes and constraining geometry make this a difficult component to rheocast. X-ray radiography is used to evaluate hot tearing over the component and is correlated to piston injection shot profile velocities. Gross hot tearing is significantly reduced by a higher injection velocity but turbulent flow entraps air. Faster injection allows more time for flow before final solidification.