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Coated metallic stents are the next generation of metallic stents with improved surface properties. To evaluate the degradation behavior of stents in vitro, different in vitro degradation models can be applied: (i) static immersion test: degradation under static fluid condition, (ii) fluid dynamic test: degradation under flowing fluid, and (iii) electrochemical corrosion test: degradation under the influence of electric potential. During these experimental procedures, stents interact with the simulated blood plasma, and degradation products are formed in the form of depositions on the stent surface, likewise in vivo experiments. These deposited crystals act as a hindrance to the application of important characterization techniques (e.g., mass loss measurement for the calculation of corrosion rate and examining the adhesion of the coating to metallic stents after fluid dynamic exposure). Therefore, to better characterize the coatings, the removal of these depositions is significant. In this work, we investigate the influence of in vitro test conditions in fluid dynamic biostability tests on the biostability of titanium oxynitride (TiOXNY) coated stainless steel stents by adapting various fluid dynamic experimental parameters. The experimental conditions are based on modification in the components of fluid dynamic setup (e.g., tubings), simulated body fluid (SBF), with and without Ca++ and Mg++ ions, and the cleaning procedure (use of water, acetone, and isopropanol). Four different experiments were conducted under various experimental parameter sets. SEM and EDX measurements were used for the identification of degradation products after each experiment. This study highlights the importance of optimized experimental conditions showing negligible depositions when utilizing Puriflex tubing or a comparable artificial vessel, SBF devoid of Ca++ and Mg++ ions, and performing sample cleaning with distilled water in an ultrasonic bath. The presented conditions were optimized for titanium oxynitride coated samples. A similar approach could be applied to other samples with or without some small variation.

The paper presents the experimental results of static and dynamic compressive tests conducted on ceramic-elastomer composites. The alumina ceramic preforms were fabricated by the four-step method: ceramic mixture preparation, consolidation under pressure, presintering, and sintering under pressure, respectively. To obtain ceramic preforms with a similar volume fraction of open pores, but with different pore sizes, alumina powder with different particle size and a ceramic binder were used, as well as pore-forming agents that were evenly distributed throughout the volume of the molding mass. The composites were obtained using vacuum pressure infiltration of porous alumina ceramic by urea-urethane elastomer in liquid form. As a result, the obtained composites were characterized by two phases that interpenetrated three-dimensionally and topologically throughout the microstructure. The microstructure of the ceramic preforms was revealed by X-ray tomography, which indicated that the alumina preforms had similar porosity of approximately 40% vol. but different pore diameter in the range of 6 to 34 µm. After composite fabrication, image analysis was carried out. Due to the microstructure of the ceramic preforms, the composites differed in the specific surface fraction of the interphase boundaries (Sv). The highest value of the Sv parameter was achieved for composite fabricated by infiltration method of using ceramic preform with the smallest pore size. Static and dynamic tests were carried out using different strain rate: 1.4·10−3, 7·10−2, 1.4·10−1, and 3·103 s−1. Compressive strength, stress at plateau zone, and absorbed energy were determined. It was found that the ceramic-elastomer composites’ ability to absorb energy depended on the specific surface fraction of the interphase boundaries and achieved a value between 15.3 MJ/m3 in static test and 51.1 MJ/m3 for dynamic strain rate.

The elastic modulus, shear modulus, and Poisson’s ratio of timber are the elastic constants characterizing its material properties. In this paper, the transient excitation method was used to dynamically measure the 10 elastic constants of the falling larch wood under the condition of the free board and cantilever board, that is, 3 elastic moduli E, 3 shear moduli G, and 4 Poisson’s ratios μ. The other two Poisson’s ratios μ were derived using the principle of orthogonality. At the same time, the elastic modulus, shear modulus, and Poisson’s ratio under static conditions were tested and verified by symmetrical four-point bending, asymmetrical four-point bending, and tensile methods. This study is expected to have good application value and practical significance for timber as an engineering structural material, which is widely used in architecture, decoration, furniture, transportation, musical instruments, and in other fields.

Elastomer is one of the important material for the hoses, sealants and tubes in the components of fuel delivery system in diesel engine vehicles due to the factor of compatibility with diesel fuel. However, concern were arise that presence of alcohol, fatty acid component and other factors such as water content in the alternative fuels which is blended biodiesel fuel and different chemical composition from the diesel fuel may increase further uncertainty to the consumer of diesel engine or diesel engine manufacturers in terms of compatibility issue. Thus this paper intends to assess current and typical test standards on their efficacy of representing the fuel system of diesel engine vehicles. Respectively, ASTM D471 are based on laboratory immersion studies and the experimental conditions are differ from the real service conditions in the fuel system of diesel engine vehicles. Even though number of previous studies regarding to the compatibility of elastomer components has been reported, there is a need to set up the exact material that present in the fuel system of diesel engine vehicles. This is especially right for elastomers since their resistance is mainly depends on their elemental compositions. As such, introduction of the dynamic testing approach that may be applied when assessing the compatibility study between blended biodiesel fuel that simulate the actual fuel system of a diesel engine vehicles before carrying out in the field trials.

Prestressed high-strength concrete (PHC) pipe pile has the advantages of high single pile bearing capacity, a wide range of applications, good driving resistance, fast construction speed, etc. It has been widely used in high-rise buildings, bridges, ports, and other industries. The application of extra-long PHC pipe piles with a length of more than 50 m is increasing. However, there are few studies on the drivability and hammering criteria of extra-long PHC piles. To analyze the drivability of extra-long piles and predict their bearing capacity, in this paper, high-strain dynamic tests were carried out on 14 test sections with the pile foundation of Temburong Bridge in Brunei as the research background. The hammer stop control criteria calculated according to the Hiley formula would lead to excessive hammering. Three types of damage occurred during construction: pile shaft breakage, weld tearing, and pile head breakage. The weight and drop height of the piling hammer selected for this project were appropriate, and the extra-long test piles can be hammered to the design depth. The values of Cp (Compression of the pile) and n (the efficiency of the blow) were fitted based on the dynamic test data, which provided a more accurate reference for the selection of subsequent piling parameters of the project. It provides a more accurate calculation method for predicting the bearing capacity of extra-long PHC piles and provides control criteria for pile stopping and a scientific basis for their design and construction.

In this work, dynamic test results of D-bolts are presented. The rock bolt specimens studied are 20 and 22 mm in diameter and 0.8–1.5 m in section length. The bolts were tested at an impact velocity of 5.4–6.2 m/s and with impact energy varying from 10 to 60 kJ. In total, over 50 drop tests were conducted during a period of three years. The dynamic tests show that a D-bolt section of 22 mm × 1.5 m can sustain an impact of 56 kJ of a dynamic impact and absorb 60 kJ of energy prior to failure. The maximum impact energy of the 22 mm bolt is thus 37 kJ/m of bolt and the maximum energy absorption is 40 kJ/m. The displacement of the D-bolt increases linearly with the impact energy. A theoretical solution has been obtained for the relationship between the impact energy and the displacement of the bolt. It states that the energy absorption of a D-bolt section is proportionally related to the volume of the bolt section and the tensile strength and ultimate strain of the bolt material. It was also found that the magnitude of the impact energy determines whether or not the bolt fails, while the impact momentum determines how long the impact lasts. The impact duration increases linearly with momentum as long as the bolt shank does not fail.

Wood is a non-homogeneous and orthotropic natural polymer material. It is important to test the wood shear modulus and elastic constants accurately and reliably using dynamic methods. Based on the introduction of the advantages of six common methods for dynamic testing of wood shear modulus, such as free plate torsional mode method, free bar torsional vibration method, and Timoshenko beam iterative method, issues associated with the applicability and accuracy of these methods are also pointed out. Recent methods, such as the free square plate torsional mode method and the square plate static torsional strain method, that were developed to dynamically test the shear modulus of wood and wood composite materials, are presented as effective ways to tackle these issues. These new approaches are expected to provide beneficial technical support for using small specimens, overcoming the size effect of specimens, simplifying the testing procedures, improving the test accuracy, and expanding the application range in the dynamic testing of wood shear modulus. These approaches have practical significance in promoting the industrialization and development of structural engineering, furniture and interior decoration, transportation, military, and musical instrument industries.

This paper investigates the collapse diagrams (energy-absorption and efficiency diagrams) under dynamic compression tests (drop tests) with an impact loading speed of 3.09 m/s. Experimental tests were carried out at room temperature on seven different types of closed-cell rigid polyurethane foams with densities of 40, 80, 100, 120, 140, 145 and 300 kg/m 3 respectively. Based on the measured load-displacement curves, authors plotted the variation of peak stress, energy-absorption and efficiency attributes with respect to density for each type of foam, highlighting the optimum foam density (100 kg/m 3 ). The influence of density and loading direction (in-plane and out-of-plane) on the main mechanical properties are also discussed. Following the investigations it was observed that both efficiency and energy absorption diagrams shows similar results, leading to the conclusion that both methods are reliable. Considering the test setup, a finite element analysis model was developed that aimed to replicate the experimental procedures. Simulations were performed in the com-mercial software Abaqus/Explicit using the implemented Elastic/Crushable foam constitutive model and using the static and dynamic test data for calibration. The energy-absorption and efficiency diagrams obtained from simulations were compared with the experimental data.

This paper presents the dynamic characteristics and seismic performance of the Chen Xiang Pavilion in Xi’an and the influence of the lower stylobate on the dynamic response of the upper wooden structure. An in situ dynamic test was conducted under ambient vibration to detect the natural frequencies and vibration modes of the structure. Three numerical models, including the upper wooden structure, the lower stylobate, and the whole structure (wooden structure and stylobate), were established. Dynamic characteristic and seismic response analyses were performed on the calculated models to investigate the influence of the lower stylobate on the dynamic response of the upper wooden structure. The simulation results indicated that the lower stylobate significantly affected the dynamic characteristics of the upper wooden structure above the third order. The seismic responses of the upper wooden structure were amplified because of the lower stylobate. Under different excitations, the displacement response of the whole structure was up to 1.99 times relative to the upper wooden structure, and the structural shear forces were increased by 15.3%. The dynamic amplification coefficient was magnified from 0.742~0.948 to 1.024~1.776. The Chen Xiang Pavilion has a good energy dissipation capacity, but the lower stylobate is unfavorable for its earthquake resistance.