Shock Test Methods Research Articles

Surface evolution of vermicular cast iron in ultra-high temperature combustion with different single-pulsing duration

The key components in combustion chamber of high power density diesel engines are apt to be damaged rapidly under abnormal combustion. To investigate the surface damage behavior and evolution mechanism of vermicular graphite cast iron in unsteady combustion, a self-developed plasma thermal shock test method was adopted. And the effect of the single-pulsing duration (0.2, 0.5, 5, and 50 s) of combustion on reciprocating thermal shock characteristics was mainly studied. Results showed that as the sample with the longest loading duration (50 s) exhibited the highest mass gain rate (0.05 mg/s), thickness growth rate (0.096 μm/s), roughness (1.889 μm), and hardness (515 HV). The cumulative thickening and spalling of the oxide layer during the plasma impact is the main cause of the changes in ablation rate and surface roughness. And the bainite phase transformation in the heat affected zone increased the hardness of the material.

ЄВРОПЕЙСЬКА ПРАКТИКА ВИРІШЕННЯ ПРОБЛЕМ ЕФЕКТИВНОГО ФУНКЦІОНУВАННЯ ПОВЕРХНЕВОЇ ОБРОБКИ ПОКРИТТЯ. ВІДПОВІДНІСТЬ ХАРАКТЕРИСТИК ПОВЕРХНЕВОЇ ОБРОБКИ ТЕХНІЧНИМ УМОВАМ ДСТУ EN 12271:2021 (EN 12271:2006, IDT)

Introduction. The wearing course of a road pavement is in complicated operational conditions in combination with adverse weather and climatic factors that are characteristic of the country for most of the year. These factors make high demands on the wearing course, in particular arranged by the method of a surface dressing. European practice of solving these issues is based on the provisions of a set of standards that can serve to solve the problems of effective functioning of a surface dressing on roads in Ukraine. Problem statement. The introduction of the requirements of the Association Agreement between Ukraine and the EU [1] into the road sector on a new favorable regime for economic relations, improvement of trade and investment are key factors in economic modernization and sustainable development of the country. European realities indicate that one of the prerequisites for the effective functioning of the road network is, first of all, implementation of modern standards. Actually, in our country there is an urgent need for their updating, in particular for the modern practice of solving the issues for the arrangement of surface dressing of the pavement, especially its design and quality control of work. Therefore, for implementation of the requirements of this Agreement, “DerzhdorNDI” SE has prepared a comprehensive set of national standards in this area with an identical degree of compliance with European requirements. Purpose. The purpose of the work is to promote the implementation of national standards with an identical degree of compliance with European requirements for the efficient operation of layers, arranged by the method of surface dressing on the roads in Ukraine. In this regard, at the present stage, only those requirements are considered, which are set out in the DSTU EN 12271: 2021 (EN 12271: 2006, IDT) «Surface dressing. Specifications» which is being prepared for publication by the National Standardization Body of Ukraine. The related standards, which are applied as a whole, will be updated and presented after their entry into force in the following parts of the article for the acquaintance of the road community. These standards are: –– DSTU EN 12272-1:2021 (EN 12272-1:2002, IDT) Surface dressing - Test methods - Part 1: Rate of spread and accuracy of spread of binder and chippings [2]; –– DSTU EN 12272-2:2020 (EN 12272-2:2003, IDT) Surface dressing - Test methods - Part 2: Visual assessment of defects [3]; –– DSTU EN 12272-3:2020 (EN 12272-3:2003, IDT) Surface dressing. – Test method - Part 3: Determination of binder aggregate bonding by Vialit plate shock test method [4]. Materials and methods Analysis of the national standard DSTU EN 12271: 2021_ (EN 12271: 2006, IDT) Surface dressing - Requirements with identical degree of conformity EN 12271: 2006 (version en) Surface dressing - Requirements[5]. Results The requirements of the national standard for the effective functioning of the surface dressing of roads in Ukraine are considered, further use of which provides an opportunity to improve the performance of works for its arrangement. Conclusion.The implementation of the requirements of the standard will contribute to the establishment of scientifically sound standards for surface dressing. The priority approaches proposed in it regarding requirements, design process and quality control can be approved as modern, requiring application in the road industry. In particular, it is appropriate to introduce requirements for the mandatory arrangement of the test site to confirm surface dressing performance (Type Approval Installation Trial (TAIT)), or measures taking into account the specifics of Factory Production Control (FPC). The use of the requirements of the standard will be facilitated by the development of country regulations or practical recommendations based on regional local conditions, and their implementation in order to create the most relevant areas of effective forms of improving the quality of surface dressing.

Experimental study on mechanical properties of new biaxial compression wire rope isolator

<p indent=0mm>Wire rope isolator is widely used in the field of vibration isolation and shock resistance of naval equipment. To overcome the shortcomings of the poor tensile performance of the traditional wire rope isolator, a new biaxial compression wire rope isolator was designed, and the performance characteristics of the new biaxial compression wire rope isolators and spherical wire rope isolators were tested using vibration and shock test methods. By conducting a comparative experiment, the characteristics of the performance difference are studied. The frequency sweep test results show that the resonance peak of the spherical wire rope isolator is larger than that of the new one at the natural frequency. The fixed frequency test finds that the vibration performance of the new and the spherical wire rope isolator is not much different under different working conditions. The shock test results show that the shock isolation rate of the new biaxial compression wire rope isolator is above 82.5%, and the shock isolation rate in all working conditions is greater than that of the spherical wire rope isolation system, which effectively improves the tensile performance of the spherical wire rope isolator. The new biaxial compression wire rope isolator further improves the shock resistance of the vibration isolator on the basis of maintaining the original vibration isolation effect of the spherical wire rope isolator.

Critical analysis and innovation propositions to the heat and thermal shock test method of the Brazilian Standard NBR 15575 (2013)

The tests of Brazilian Standard NBR 15575: 2013 are part of the knowledge of the civil construction industry, but the heat and thermal shock test is innovative and does not have a consolidated history. The research objective is to analyze the testing critically and present proposals based on data meta-analysis. Results showed that the test is very inaccurate in describing the procedure and equipment. This study proposed adjustments and innovations in the test to provide more reliable results, but it does not make propositions regarding visual inspection and the number of cycles. The study concluded that the lack of information on the testing has direct responsibility for the results and that the suggested proposals have the potential to be incorporated.

탄성플랫폼 충격응답 스펙트럼 기준에 따른 다기능콘솔 충격해석 연구

Prior to installation in a navy ship, shipboard equipment should be qualified by shock test requirements. The multi-function console mounted on the elastic platform of the ship should also withstand given shock loads. In this study, both real shock test methods, as well as numerical computer simulations using the finite element method were used to verify structural durability under shock load conditions. First, we used domestic test facilities to perform possible shock tests, including an impact hammer test, a drop table test and a shaker shock test. Full model tests satisfying the shock response spectrum level were performed. Thereafter, an analytical model of the complex console structure was built by the finite element method. Finally, numerical results were verified by modal test results of the real product and an FEA analysis was also performed with a full model transient response analysis.

Investigation on the thermal properties of the multilayered ceramic coatings deposited using atmospheric plasma spraying

Atmospheric plasma spraying was employed to deposit Zirconia/Alumina (ZrO2/Al2O3) and Zirconia/Alumina-Titania (ZrO2/Al2O3-TiO2) multilayer coatings with bonding material (Ni-Cr-Al) on the EN31 Mild Steel substrate. The investigation was carried out on multilayer ceramic coated specimen by thermal torch and shock test methods. The coated specimens were prepared as per ASTM standards. Micro structural analysis was carried out using scanning electron microscope to investigate the thermal resistance of the two different multilayer ceramic coatings. The results show that the multi-layered ZrO2/Al2O3 coating possesses improved thermal properties when compared to ZrO2/Al2O3-TiO2 multilayer coating.

Impact of External Temperature Environment on Large FCBGA Sn-Ag-Cu Solder Interconnect Board Level Mechanical Shock Performance

The mechanical stability of solder joints in electronic devices with Sn-Ag-Cu is a continuous issue since the material was applied to the industry. Various shock test methods were developed and standardized tests are used in the industry worldwide. Although it is applied for several years, the detailed mechanism of the shock induced failure mechanism is still under investigation. In this study, the effect of external temperature was observed on large Flip-chip BGA components. The weight and size of the large package produced a high strain region near the corner of the component and thus show full fracture at around 200G level shock input. The shock performance at elevated temperature, at 100℃ showed degradation based on board pad designs. The failure mode and potential failure mechanisms are discussed

Thermal and Microstructure Stability of Cordierite–Mullite Ceramics Prepared from Natural Raw Materials

In this study, attempts were undertaken to explore the possibilities to prepare cordierite–mullite composites with potentiality to be used as refractory materials from natural raw materials. Solid state reaction sintering different sample powders at different temperatures from 1,250 to 1,400°C has been applied to prepare cordierite–mullite ceramics. XRD has proved the presence of cordierite and mullite in different ratios as major phases. Thermal shock test method based on heating–quenching procedure, supplemented by scanning electron microscopy and mercury intrusion porosimeter, has been used to demonstrate the thermal stability of different samples.

Reliability Failure Analysis of PCB and its Technological Improvement

Reliability failure analysis is extremely important in the manufacturing process of PCB (Printed Circuit Board). In this paper, we use thermal shock test method to analysis the electrical interconnection reliability of PCB in harsh environment. Also taking into account the reliability of PCB is closely related to its design and technology, approaches of technological improvement are proposed. Finally through temperature shock test method, the results show that the reliability of PCB designed with improved technology is enhanced.

Shock Test and Acceleration Analysis Methods of Marine Diesel Engines to Underwater Explosions

Shock test of marine diesel engine is the important content for ship anti-shock research. Plentiful shock tests of equipments have been carried out abroad, but there is no detailed test methods of diesel engine. According to simulation results, 8-channel acceleration test points are determined. Because diesel engine is working, the measured shock acceleration is interfered by vibration signal. Orthogonal wavelet decomposition and wavelet noise reduction methods are used to separate shock component from test results. The seperated shock component consists of two parts. One is the low-frequency part caused by the shock from diesel foundation and then attenuation through the isolator, the other is the high-frequency part caused by the secondary shock of the retainer.

Stimulation on Anti-Shock Characteristic of Diesel Engine

With more and more attention being paid to anti-shock of the warship by many country’s navy, it is of practical significance to study the anti-shock characteristic of the diesel engine which belongs to the A class facility on warship. Owing to the high price of shock test, simulation combined with partial shock test methods are adopted by many countries to ensure the facility’s anti-shock performance. A numeric virtual platform of TBD234V6 diesel engine generator set is built by means of software MSC.ADAMS and four machine feet of the diesel engine are modeled flexibly. The virtual shock test of the generator set is conducted on this platform according to the German shock standard BV043/85 and anti-shock performance limits of the machine feet is obtained. Hammer experiment is also carried out on the real generator set. After the comparison of the simulation results and the experiment results, the deficiency aspects need to be improved are pointed out at last.

A new scuffing shock test method for the determination of the resistance to scuffing of coated gears

An improvement in the scuffing resistance of toothed gears is achievable by e.g. the deposition of thin, hard coatings onto the gear teeth. However, the testing of the scuffing resistance of coated gears requires the application of specialised test methods.This paper presents a new test method, designed by the authors, called “gear scuffing shock test for coatings”. This method is based on the test method denoted as FZG S-A10/16,6R/110 developed at the Technical University of Munich. Because the FZG test method is dedicated exclusively to lubricating oils, its application for testing coated gears required introducing significant modifications.The developed method has been verified during the testing of the scuffing resistance of gears coated with the low-friction a-C:H:W coating and composite low-friction MoS2/Ti coating. Various material combinations were tested: coating–coating (both gears coated), coating-steel, steel-coating, and for reference steel–steel (both gears uncoated). Mineral, automotive gear oil of API GL-5 performance level, and SAE 80W-90-viscosity grade was used for lubrication.It has been shown that this test method can be successfully applicable to test the scuffing resistance of coated gears—it has a resolution good enough to differentiate between the tested material combinations.

Thermal Shock Tests and Thermal Shock Parameters for Ceramics

Thermal shock test methods and thermal shock parameters for ceramics were reviewed from the following viewpoints: (1) The test methods should be based on the precise estimation of both temperature and thermal stress distributions in a specimen taking into account the temperature-dependent thermo-mechanical properties; (2) The thermal shock parameters must be defined as a physical property of the materials and described as a function of temperature at the fracture point of the specimen; (3) The relation between the strength and fracture toughness of brittle ceramics under a thermal shock load must be the same as the relation under a mechanical load. In addition, appropriate thermal shock parameters should be defined by the thermal shock strength and thermal shock fracture toughness based on stress and energy criteria, respectively. A constant heat flux method is introduced as a testing technique suitable for estimating these thermal shock parameters directly from the electric power charged.

Thermal Shock Cracks Initiation and Propagation of WCp / Steel Substrate Surface Composite at 500°C

In order to provide a theoretical basis for the study of thermal fatigue properties on surface composites, thermal shock cracks initiation and propagation of WCP reinforced high chromium steel substrate surface composites were studied by thermal shock test method at 500 °C. The results show that cracks initiation and propagation begin within a few thermal shock cycles, and after 15 thermal shock cycles, the composites remain intact, indicating a good thermal shock resistance. The thermal shock cracks consist mainly of longitudinal and transverse cracks. Within a few thermal shock cycles, the initiation and propagation of longitudinal cracks play a dominant role; however, with the increase in the number of thermal shock, the transverse cracks may play a key role as the length and number of both types of cracks increases. However, the increase is slow. The longitudinal cracks are mainly caused by the first class thermal stress and the transverse cracks result from the culminant effects of the first and second thermal stress, interacting with each other.

Advances in Shock Testing Facilities for Naval Shipboard Equipments

The capability to withstand non-contact underwater explosions (UNDEX) is an important aspect to be emphasized in the design of modern warships, and shock testing is one of the efficient methods to qualify the ability. A brief history on the research of shock testing of naval shipboard equipment as well as major means in evaluating anti-shock performance of warship equipment is introduced first in this paper. Three prevailing shock test methods: UNDEX testing, virtual shock trial and land-based test with shock test machines are presented with the focus on the advances in shock test machines in US and Europe. Comparison of current shock testing facilities is also given. Moreover, some new concepts of shock test machines are reviewed as well, and three major directions of the development of shock test machines are concluded. The first trend is that shock testing machines are required to generate positive and negative shock pulse to simulate real UNDEX environment made up of shock wave followed by bubble pulse and structural whipping. The second is that shock test machines can test heavy equipments, and the last is that shock pulses can be controlled and customized conveniently.

Aplicação da ferramenta SWOT para avaliação das técnicas de dano ao choque térmico em materiais refratários

A literatura indica diversos tipos de ensaios e diferentes métodos de avaliação de dano por choque térmico. Adicionalmente sabe-se que, em determinadas aplicações, esse tipo de dano é um dos principais responsáveis pela degradação do revestimento refratário. Neste contexto e buscando a melhor forma de reproduzir as condições em serviço do revestimento refratário, o presente trabalho foi realizado visando analisar qual tipo de ensaio de choque térmico e método de avaliação do dano são os mais adequados para avaliar o desempenho destes materiais. Essa análise foi baseada em uma revisão bibliográfica e resultados obtidos em laboratório, em que se comparou e avaliou as vantagens e desvantagens dos métodos mais relevantes encontrados na literatura. Por fim, com o auxilio da ferramenta SWOT foi possível verificar se o método adotado pelos autores desse trabalho é adequado para auxiliar na seleção do refratário para aplicação em calcinadores de leito fluidizado.

Binding Performance of a Zirconia Framework Material and Veneering Porcelain

In this study, the binding performance of a Cercon-based zirconia framework material and special Cercon Ceram S zirconia veneering porcelain is discussed. Rectangular 30 mm × 20 mm × 2 mm porcelain blocks were made from zirconia using the CAD/CAM system. The 2 mm veneering porcelain was then sintered onto blocks at a temperature of 850-800°C with a loading speed of l mm/min. The shear bond strength of the interface was tested. Sintering was studied by visual observation, scanning electron microscopy, energy dispersive spectroscopy (EDS), thermal shock test and other methods. Excellent sintering results of the zirconia framework material and veneering porcelain can be achieved. The cross-sectional morphology of the samples, observed by SEM, shows a uniform, fine, and smooth texture for the veneering porcelain, whereas that of the zirconia framework material shows a rough surface with a uniform and compact texture. EDS results indicate that a small amount of A12O3 and SiO2 is present in the zirconia area, and no ZrO2 or Y2O3 is detected in the veneering porcelain area. No interlayer radial crack or flaw is found throughout the entire thermal shock test of the samples at 60-240°C. Thus, the cracking temperature of the samples is pegged at T&gt;240°C. The shear bond strength of the interface is 32.62±5.77 MPa. Chemical element infiltration exists between zirconia and the veneering porcelain, indicating the chemical bond between the two. An excellent match between the Cercon-based zirconia framework and the special veneering porcelain can be achieved, which can satisfy clinical requirements.

Shock resistance of supercharged boilers through integration with ship structure

The non-linear finite element software ABAQUS was used to simulate the dynamic response of a marine supercharged boiler when subjected to impact loading. Shock resistance was analyzed by the time-domain simulation method. After exhaustive simulations, the effect of air pressure induced by different working conditions on the shock response of a supercharged boiler was reviewed, leading to conclusions about the variability of structural response with different loading parameters. In order to simulate the real impulsive environments of supercharged boilers, the integration of equipment and ship structure was then primarily used to analyze shock response. These distinctly different equipment shock test methods, run under equivalent work conditions, were compared and the causes of discrepancy were analyzed. The main purpose of this paper is to present references for the anti-shock design of marine supercharged boilers.

210 Differences of Natural Frequency between Conventional Cut-off Wheel and Wheels with Slits

Natural frequencies of three types of grinding wheel; a wheel with no slits, with 5-side slits and with 6-side slits, were observed by hammer shock test and finite element method computer simulations. Frequency modes obtained by hammer shock test had good agreement with those obtained by computer simulations. Therefore, it is easy to determine the natural frequencies of grinding wheel by computer simulation without any specialized laboratories or machine shops. Furthermore, it was found that wheels with slits have lower natural frequencies than the one with no slits. Our results may be useful in avoiding undesirable resonance vibrations of wheel.

Pyroelectric Effects on 1T-1C Fram and 1Tr Fram

AbstractPyroelectric effect on ferroelectricity was examined for PZT capacitors with diodes in series. It was observed that the magnitude of the polarization reversal increases as heating rate increases. The polarization reversal begins to decrease as heating rate becomes very high, which may stem from the fact that pyroelectric charges flow through the PZT film at high temperature as the film loses its resistance at the elevated temperature. A pure remanent polarization reversal model is suggested for the polarization reversal caused by pyroelectric charges. Based on the above results, a thermal shock test method is proposed for quality control of FRAM products. The thermal shock test reveals that pyroelectric effect can be minimized by controlling process for 1T-1C FRAM. It was also observed, by the thermal shock test, that imprint dominates pyroelectric effect in 1Tr cell with MFIS structure.