Key Engineering Materials Vols. 577-578

Abstract: This paper introduces the experimental corrosion tests that are carried on the existing weathering steel structures in the Czech Republic. The influence of the position and location of the surface in the structure on the resulting corrosion rates can be evaluated using this experimental testing. Typical surfaces of steel bridges are tested, e.g. webs of main girders, upper and lower surfaces of flanges, surfaces affected by leaking salt solutions. Results of the corrosions tests are used for the specification of corrosion prediction model.

Abstract: In the present work a piezoelectric based structural health monitoring (SHM) system is analyzed with the aim of assessing the ability of the piezoelectric patch to detect both edge and embedded delaminations proper of flange-skin composite laminated structures. The boundary element model is developed for piezoelectric solids and is implemented by taking advantage of the multidomain technique to model laminated and cracked configurations. A non-linear spring model interface is then implemented in conjunction with an iterative procedure allowing for the simulation of the finite stiffness of the bonding layers as well as of the non-penetration condition of the delamination surfaces. The dynamic behavior of the damaged structures and of the bonded piezoelectric patch is modeled by means of the dual reciprocity approach. To fully characterize the structure response the fracture mechanics behavior is studied in terms of energy release rate G and mode-mix phase angle Y. Finally, a damage index based on the electrical current output of the SHM system is introduced as an effective identification parameter of the flange-skin delamination occurrence.

Abstract: In Order to Improve the Joining Strength of Friction Stir Spot Welded PVC Joint, Sic Particle was Compounded by the Stirring in the Welding Process. the Influence of Sic Particle Sizes on the Joining Strength was Investigated in this Study. in Case of the Specimen Compounded Sic Particle with Size of 14.6μm, Heat Generated during the Process Significantly Increased and Resulted in Increasing Width of Welded Region. however, According to Result of Hardness Test, Excessive Heat Generated during the Process Led to Degradation of Mechanical Property of the Welded Area in the Specimen Compounded Sic Particle with Size of 14.6μm. on the other Hand, in Case of the Specimen Compounded Sic Particle with Size of 6.5μm, Width of Welded Area was Smaller than that of the Specimen Compounded Sic Particle with Size of 14.6μm and was Similar as that of the Specimen Compounded Sic Particle with Size of 0.5μm. it was Observed that Hardness of the Welded Area was Uniformly Higher in the Joint Compounded Sic Particle with Size of 6.5μm. Specimen Compounded Sic Particle with Size of 6.5μm Showed the Highest Strength among the Joints Tested. it is Considered that the Joining Strength was Affected by both Width and Mechanical Property of the Welded Area.

Abstract: In this paper, the effects of collision velocity on bullet deformation were discussed and performance of protection board made of PC (polycarbonate) plate was estimated. The deformation of the bullet and the PC board after collision were measured by 3-dimensional digitizing machine.Furthermore, the bullet collision analysis was performed by FEM analysis code "LS-DYNA", and the impact load carrying capacity of PC plate was discussed by comparing the experimental results with the analytical ones

Abstract: The widespread Von Mises plasticity model fails to take the hydrostatic and the Lode angle effects into account and the assumption of this model is not valid for all types of metallic alloys. Hence in the present work the applicability of the Von Mises plasticity model in applications on a Ti-6Al-4V Titanium alloy have been analysed. A virtual test methodology, combination of experiments and numerical analysis have been developed. For this purpose various tensile tests on different specimen shapes have been carried out experimentally. These tests have been subsequently numerically reproduced to calibrate a constitutive law which fits every single test best, highlighting the possible effect of triaxiality and Lode angle on plasticity (strain hardening behaviour). An analysis of the specimen fracture surfaces have been carried out to evaluate possible effect of triaxiality and Lode angle down to a microscopic level.

Abstract: Fatigue characteristics of bolted joint tightened with a steel bolt have been discussed extensively. However the fatigue characteristics of bolted joint tightened with a nonferrous bolt have not been sufficiently discussed. In this study, two types of fatigue tests, axial fatigue tests and transverse fatigue tests, for nonferrous bolts were conducted. The nonferrous bolts used in this study made of AZ31 and AZX912 magnesium alloy and A5056 aluminum alloy. The results of both fatigue tests showed that the fatigue limits of the A5056 bolt were the highest of all. The fatigue limits of two kinds of the magnesium alloy bolts were almost the same in both fatigue tests. However the ration of the axial fatigue limits to the transverse fatigue limits were different according to the bolt materials.

Abstract: Ultrasonic Corrosion Fatigue Tests were Conducted for SUS329J3L in Air and 3%NaCl Aqueous Solution. Reduction of Giga-Cycle Corrosion Fatigue Strength was 12.5%. Corrosion Pit was Observed on Corrosion Fatigue Crack Initiation Area. Striation was Predominantly Observed on Crack Propagation Area both in Air and 3% Nacl Aqueous Solution. it can be Concluded that the Reduction of Corrosion Fatigue Strength of SUS329J3L is due to the Corrosion Pit Formation at Corrosion Fatigue Crack Initiation Area.

Abstract: In this paper, the torsional rigidity of micro-lattice plates is investigated using a FE analysis. In particular, the effect of the overall length of the plate and the unit-cell geometry on the torsional rigidity are discussed. Also, a theoretical approach, based on classical beam theory, for predicting the rigidity is proposed, and its effectiveness is verified by comparing with FE results.

Abstract: Fatigue Property of an Extruded AZ61 Magnesium Alloy with the Processing Layer Introduced by Machining was Investigated. Rotating Bending Fatigue Tests were Carried out with the Specimen with and without the Processing Layer. According to Results of the Fatigue Tests, Fatigue Life Significantly Increased by Introducing the Processing Layer to the Specimen Surface. Fatigue Crack Initiation and Propagation Behaviors were Observed by Replication Technique during the Fatigue Test. Fatigue Crack Initiation Life of the Specimen with the Processing Layer was Slightly Longer than that of the Specimen without the Processing Layer. Higher Fatigue Crack Growth Resistance was also Observed when the Fatigue Crack was Growing in the Processing Layer in the Specimen with the Processing Layer. the Longer Fatigue Life Observed in the Fatigue Test in the Specimen with the Processing Layer could be Mainly due to the Higher Crack Growth Resistance. it is Speculated that the Fatigue Strength can be Controlled by Change in Condition of Machining Process. it could be Effective way in Industry to Improved Fatigue Strength only by the Cutting Process without Additional Surface Treatment Process.

Abstract: The Failure of the Interface between Fiber and Matrix under Transverse Loading is the Key Factor Controlling the Failure Process in Composite Materials. the Debonding Process of a Fiber within a Unidirectional Composite is Studied by Finite Element Analyses Using a Representative Volume Element. the Energy Release Rate is Calculated for Different Fiber Volume Fractions. Two Load Cases are Taken into Account, Pure Transverse Tension and Shear Loading.