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Рассматривается проблема имитации эксплуатационного ударного нагружения элементов космического аппарата (КА) при проведении его наземных испытаний на прочность. Предлагается использование одиночных механических ударов. Анализируется понятие эквивалентного механического удара. Обосновывается подход к определению величины и длительности эквивалентного удара, The problem of simulating operational shock loading of spacecraft elements during its ground strength tests is considered in this paper. It is proposed to use single mechanical shocks. The concept of equivalent mechanical impact is analyzed. Substantiates the approach to determining the magnitude and duration of an equivalent impact, Вестник НПО им. С.А. Лавочкина, Выпуск 2 (60) 2023, Pages 70-77

International audience; The primary concern of the current study is estimating the repetitive shock induced damages leading to cumulative fatigue on corrugated cardboard boxes experimentally and numerically. Repetitive shock tests were performed on boxes using a vibration table to construct a Damage Boundary Curve (DBC). To computationally determine this curve, a finite element approach is proposed using an elastoplastic homogenization model for corrugated cardboard. The proposed model was implemented in the finite element software ABAQUS. Thanks to adopted model simplifications, a box can be easily and reliably modelled as a homogenized structure. A calibration method is used to compute a set of effective parameters in homogenized model in order to keep its behavior qualitatively and quantitatively close to the response of a full structural model. For verification, the identified model is used to simulate the box compression test. To replicate the experimental tests, simulations of successive repetitive shock pulses are carried with the proposed model for oligocyclique and limited endurance fatigue. To reduce computational costs, we propose a simple method for unlimited endurance fatigue by extrapolating a trend line after some training cycles. The proposed method shows good agreement with experimental results.

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2021-03-01, 資料番号: PA2110030000

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2021-01-05, 資料番号: PA2110029000

Pyroshock events during a Nanosatellite launch might lead to mission failure. Therefore, it is important to be able to simulate such events during mission design. This study introduces a procedure to perform the Nanosatellite qualification shock test using a metal-to-metal impact facility. Such a facility was constructed with a capacity to generate mechanical shock waves up to 10 000 g for an out-of-plane (OOP) impact, and 5000 g for an in-plane (IP) impact. Furthermore, several experiments were carried out to establish a calibrating procedure, for both the IP and the OOP impacts. The experiments showed that increasing the impactor mass will raise the amplitudes of the lower frequency region of the Nanosatellite shock response spectrum (SRS) curve. Furthermore, increasing the impact velocity will introduce a higher impact energy to the SRS curve. A practical and cost-effective solution was presented to overcome the IP excitation limitation, through using a commercial silicon rubber pad as an interface between the testpod and the resonating plate. This approach proved to be successful in rectifying the lower frequency region modes for the IP impact test. The measurements were successfully validated using the positive and negative SRS approach. The experimental setup was verified using 1-D and 2-D numerical elements via the commercially available finite element analysis software ABAQUS.

During the launching of spacecraft, the on-board devices will undergo a series of pyroshock environments. In order to verify the reliability of these devices under these pyroshock environments, all of them are needed to take the shock test before launching. This paper has carried out an in-depth research on the simulation method of the pyroshock based on the true explosive excitation. In this study, a simulator containing multiple adjustment parameters is presented and the safety is considered by the design of the protective cover. And the working process of this setup is simulated with the explicit dynamic codes LS-DYNA. What’s more, the effects of the adjustment parameters on the three factors of shock Response Spectrum (SRS) of the resonant board are explored carefully. The rules achieved in this paper are verified by a typical example. The results indicate that the improved simulator can avoid the danger of explosive and make full use of the advantage of actual explosive excitation. And the test condition can be quickly realized at the simulator according to the effect rules of the three adjustable parameters. Keywords: Adjustable parameters, Maximum Expected Flight Environment (MEFE), Protective cover, Pyroshock, Shock Response Spectrum (SRS)

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2019-11-15, 資料番号: PA2010037000

In this paper, we propose a bistable shock structure based on the thermal actuation principle, which overcomes the response time limitation of heating and cooling in typical thermal actuators and enables a rapid release of energy. Thus, force with a steep rising edge can be applied on a target. Using a bistable shock structure to generate on-chip shock loads, we propose an automated and resettable method for shock testing of microstructures. We characterize the microscale shock process by high-speed camera and finite element simulation (FEM). The method can simulate the dynamic response of key structures in MEMS devices under mechanical shock conditions, and therefore, can be used to evaluate shock fracture strength of microstructures.

The COVID-19 pandemic exposed primary care (PC), and policies aimed at integrating it into provincial health systems, to a “shock test.” This paper draws on documentary analysis and qualitative interviews with PC and health system stakeholders to examine shifts in Alberta's pre-pandemic PC integration model during the first nine months of the pandemic. We begin with an account of three elements of the province's pre-pandemic model: finance, health authority activity and community activity. We describe these elements as they shifted, focusing on two indicators of change: novel virtual care billing codes and personal protective equipment (PPE) distribution channels. We draw out policy planning lessons for improving PC integration under normal and future pandemic conditions, namely, by facilitating rapid updates of virtual care billing codes, analyses of the impact of care delivery and backstopping of PPE markets and supply chains for PC.

A nonlinear dynamic model for describing shock response of half-sine programmer in shock test is constructed, in which many important factors in half-sine programmer such as size, hard nonlinearity, damping and initial impact velocity are considered, based on the damped Duffing equation, and the empirical static stiffness and shock stiffness calculation formulas of cylindrical rubber isolator. The shock pulse of half-sine programmer is measured and calculated by using shock test machine and Runge-Kutta method. Taking the minimum determination coefficient between the calculated and the measured shock pulse as the optimization objective, the parameters in the present model are determined by using quantum genetic algorithm (QGA), and meanwhile the extreme capacity in the present model for describing the dynamic behavior of half-sine programmer under shock excitations can also be verified. Experiments were implemented with drop shock test machine. The experimental results show that the present model is precise and efficient, and the prediction errors of pulse peaks and pulse widths were all below 5%, the waveform fitting errors between the calculated and the measured pulses are all less than 15%. The present results are helpful for designing the half-sine programmer.

The application of gyroscopes in harsh environments has always been a hot topic. As a high-quality material for manufacturing gyroscopes, quartz crystals need to be designed and optimized to meet the normal operation of gyroscopes in harsh environments. The Micro Electronics Mechanical System(MEMS) quartz tuning forks resonant gyroscope is one of the quartz gyroscopes. The elastic structure (V-shaped beam) between the anchor support point and tuning forks plays a vital role in the MEMS quartz tuning forks resonant gyroscope. This structure determines the natural frequency of the gyroscope, and more importantly, determines the shock resistance of the gyroscope structure. In this article, the MEMS quartz tuning forks gyroscope with different V-shaped beam thicknesses are simulated and analyzed by finite element analysis simulation software. After the modal analysis and shock simulation (the half-cycle sine shock pulse with amplitude of 1500 g (g is the acceleration of gravity) and duration of 2 ms in the six shock directions), the results show that when the beam thickness is 80 &mu, m, the maximum stress is 94.721 MPa, which is less than the failure stress of quartz crystal. The gyroscope&rsquo, s shock resistance is verified through shock testing.

In order to achieve reasonably aero-engine landing shock data induction, first filter the shock data samples through ESD (Energy Spectrum Density) and SRS (Shock Response Spectrum), and then Actual SRS and Standard SRS were given on relevant standards and mathematical statistical methods. Casing shock of aeroengines were measured during landing, and Actual SRS and Standard SRS of two types of aero-engine installed in the same aircraft were obtained. The differences of shock characteristics on different directions in the same position were analyzed with the differences of shock characteristics of two types of aero-engine. The results show that the shock characteristics on different directions on the same position may vary greatly, and it is possible to reduce the risk of shock damage through changing installation direction of equipments or structures. Shock characteristics of two types of aero-engine may vary greatly, so that measured shock data of corresponding aero-engine should be selected as test condition on the shock test of airborne equipments or structures. The conclusions provide some guidance for shock absorption design of aero-engine and installation of airborne equipment.

Zırhlı araçların mayın patlamasına karşı korunması için son yıllarda ciddi çalışmalar yapılmaktadır. Zırhlı araçların patlama etkisine karşı dayanımlarını arttırmak için enerji sönümleme kabiliyetleri yüksek malzemeler tercih edilmektedir. Sunulan Yüksek Lisans Tezinde koruge (ondula) geometrisine sahip çekirdekten oluşan sandviç plakların şok dalgası etkisi altında sönümleme performansı Sonlu Elemanlar Yöntemi ile incelenmiştir. İlk çalışma olarak dört model oluşturulmuştur. Bu dört model şok tüp testlerindeki numuneler ile belirlenmiştir. Ardından Sonlu Elemanlar Yöntemi ile şok yükü altındaki performansı incelenmiştir. Şok tüp test cihazında Yüksek Hızlı kameralar desteği ile gerçekleştirilmiş olan şok testlerinden elde edilen deplasman-zaman değişimleri Sonlu Elemanlar Modellerinin doğrulanması için kullanılmıştır. Sonlu Elemanlar analizleri Ls-Dyna kullanılarak gerçekleştirilmiştir. Aynı deplasman değerlerini elde etmek amacıyla CONWEP patlayıcı modeli oluşturulmuş ve patlama analizleri gerçekleştirilmiştir. Patlama analizlerinde elde edilen deplasman değerleri şok testi ve şok analizi ile karşılaştırılıp değerlendirilmiştir. Maksimum deplasmanların birbirlerine çok yakın olması farklı bir modelin sadece patlama analizi ile doğrulanmasının önünü açmıştır. İkinci çalışma olarak koruge çekirdek içerisindeki hücre boşluklarının balistik jel dolgu (viskoelastik jel) ile doldurma yönteminden elde edilen alternatif sandviç modellerin performansları incelenmiştir. Viskoelastik jel için beş model oluşturulmuştur. Viskoelastik jel dolgulu sandviç tasarımlarının Sonlu Elemanlar Analizleri CONWEP yöntemi kullanılarak gerçekleştirilmiştir. Çalışma sonucunda viskoelastik jel dolgunun şok dalgasını sönümlemeye dönük sağladığı iyileştirme ortaya konmuştur. In recent years, major works have been carried out to protect armored vehicles against mine blast. In order to enhance the strength of armored vehicles against blast effects, materials that have high energy absorbing capability are preferred. In the presented Master Thesis, damping performance of sandwich plates consisting of core with corrugated geometry under the effect of shock wave was investigated with Finite Element Method. Four models were created for the first study. These four models were determined by samples in the shock tube tests. Then, performances under shock load were investigated with the Finite Element Method. Displacement-time changes obtained from the shock tests performed with the support of High-Speed cameras in the shock tube test device were used to verify the Finite Element Models. Finite Element Analyses were performed using Ls-Dyna. CONWEP blast model was created to obtain the same displacement values and blast analyses were performed. The displacement values in the blast analysis were compared and evaluated by shock test and shock analysis. The maximum displacements are very close to each other paved the way for a different model to be verified by only the blast analysis. As the second study, performances of alternative sandwich models obtained by filling cell cavities in corrugated core with ballistic gel filling (viscoelastic gel) method were investigated. Five models were created for the viscoelastic gel. Finite Element Analysis of viscoelastic gel filled sandwich designs were performed using CONWEP method. As a result, improvement provided by the viscoelastic gel filler to dampen the shock wave was revealed.

In this work, we compared the survivability of epitaxially encapsulated (EPI) MEMS disc resonating gyroscopes (DRGs) with ten different designs up to shocks near 50,000g. Though most DRGs survived, there are clear differences in the performance of devices post shock. Devices are clustered into their respective shock groups, but some devices maintain their superior performance even in the face of extreme shock. This work expands on the previous work of understanding shock resistance in gyroscopes and which devices may maintain performance under various conditions.

Статья посвящена наземной отработке динамики посадки макета посадочного аппарата КА «ЭкзоМарс-2020», описанию параметров ударных испытаний., The article covers ground verification of landing dynamics of the ExoMars-2020 Landing Module mockup, description of shock test parameters., Вестник НПО им. С.А. Лавочкина, Выпуск 1 (47) 2020

The paper studies the simulation of shock test for a propulsion motor equipped on an AUV. According to DDAM, the modal parameters are calculated using finite element analysis. Then the input spectrum of impacting acceleration is given based on modal analysis. The response after shocking is analyzed at last. Distribution of the stress in different directions are given, showing that the shock resistance performance of the propulsion motor satisfied the shock test.

The aim of this study was to investigate the effects of vitamin E and selenium, marjoram (Origanum spp.), and ajwain (Trachyspermum ammi) extracts on growth performance and lysozyme activity of rainbow trout fingerlings. The results of this study showed that adding ajwain (1%) and marjoram (2%) extracts and Vitamin E plus selenium (1%) significantly increased (P

Equipments on shipboard have been exposed to various shock waves caused by underwater explosions such as a torpedo or mine. To survive the underwater shocks, most of equipments on shipboard should be installed with shock isolation systems. In this paper, the development of the shock absorber using ring springs has been introduced. The design approach and its non-linear numerical analysis have been investigated. The performance of the shock absorber has been not only evaluated by the shock test according to MIL-S-901D but also compared with the simulation result to verify the reasonableness of the non-linear calculation.

The breakage of boulders/cobbles in conglomeratic deposits are reported to occur along tectonic lines. The authors have been undertaking both in-situ investigations and laboratory experiments to understand the fundamental mechanism and causes of the breakage of the boulders/cobbles. Some sampling and observations are done in the close vicinity of Horai district, which is located along the famous Median Tectonic Line of Japan. In addition, some sampling of broken boulders/cobbles was done in Seno-umi in Suruga Bay, Shizuoka by Bousei-maru investigation ship of Tokai University. A drop-weight equipment was developed to carry out experiments on the boulders/cobbles sampled from Horai district, Kusanagi and Miho district of Shizuoka City, which constitute Nihon-daira formation. The authors report the outcomes of this experimental study in relation to mega earthquakes in the past. Furthermore, some numerical studies on ideal cases were carried out in order to see the stress state causing the breakage of the boulders.

International audience; Slamming is a dynamic phenomenon in which a high magnitude pulse peak pressure occurs in a short time duration when the bottom structure of a ship impacted against the sea surface. This phenomenon can cause damage in the structure due to fluid-structure interaction (FSI) thus, plays a vital role in designing and manufacturing of ships for naval applications. In this paper, high performance sandwich structure, having many opportunities and challenges for the marine structural design, were studied experimentally using a high-speed shock test machine to examine the water entry problem. In addition, a velocity control system was used to calibrate and preserve the approximately uniform velocity throughout the slamming impact. Sandwich panels with different thicknesses i.e. 27 mm and 37 mm therefore, having different stiffness's were exposed under constant impact velocities of 6 and 8 m/s at the deadrise angle 10°. Experimental results were then compared and verified by the numerical investigation based on explicit Smoothed Particle Hydrodynamics (SPH) method. This study focuses on the overall structural response, deformation, and hydrodynamic response of the structure during the dynamic impact designed for naval applications.

When designing a laboratory shock test to simulate a shock environment measured in the field, the SRS serves as a common reference. If the two SRS are the same, then the laboratory test is considered to be representative and have the same damage potential as the field environment. But, what does it mean for two SRS to be the same? What features in the SRS are most important to represent faithfully in the laboratory environment? Another question is: how can the component designer use the SRS to make design decisions to make the part robust to shock. To answer this question, one again must know what features of the SRS are important and how to use them in component design. In Chap. 4, we briefly discussed how to assess the potential severity of shock excitation on a structure when we introduced the SRS. In this chapter, we expand on that to answer those questions and assist the component designer in passing shock tests.

Classical shocks are defined by a single, one-sided shock pulse with a non-zero velocity change. There are five classical shocks: the haversine, half-sine, initial and terminal peak saw-tooth, and trapezoidal pulse shapes. Each of these shocks is easily described mathematically and can be easily replicated using shock test machines. This chapter discusses the different types of classical shocks and their unique characteristics and their similarities. Discussion of SRS properties specific to classical shocks and more generally to shocks with a non-zero velocity change is included. Also included are methods for interpreting specific SRS features, such as the low-frequency slope and the shock bandwidth, as they relate to the classical shocks.

The characteristics of a dual-pulse shock caused by an UNDEX (underwater explosion) are described through many standards. Shock signals required to evaluate the survivability of equipment by a shock test machine are also described. To generate various types of shock signals described in the standard, Shock test machines (STMs) require adjustment to various levels of shock occurring in surface ships and submarines. Therefore, the characteristics of each component of a STM should be changeable to generate various shock signals. This paper describes the concept of a STM that can generate various types of dual-pulse shocks. Moreover, this paper suggests an analytic method to determine the characteristics of each component of a STM to generate the required shock signal for various specimens. A method for adjusting the shock signals using a magnetorheological damper is specifically suggested. The results of dynamic analysis using the characteristic values of each component determined by this method shows that the required shock signal can be generated by this concept of the shock test machine.

Structure durability under shock load is evaluated by performing a shock resistance test. Saw-tooth shock wave is generated in a specific environment and transmitted to the structure. The saw-tooth shock wave is generated using a specific impact test system. In general, the impact test system is generally composed of three types: Drop, lateral and rotational. Each type of impact test system has different detail parts. This study applies the drop-type impact test system. A test table, a fixed table, and a shock programmer compose comprise the drop-type impact test system. The drop-type impact test system uses the initial height of the test table, where the specimen is mounted on. The impact velocity in the drop-type impact test is determined by the initial height of the test table. The shock programmer generates the shock wave transmitted to the specimen mounted on the test table, which is then. The shock wave transmitted to the specimen is then generated by the shock programmer material. Parameter research of the parameter testing on the shock programmer has to be performed using the drop-type impact test system to generate the saw-tooth shock wave with non-linear characteristics. This study generates the saw-tooth shock wave by designing and simulating the lead shock programmer. Lead is considered as the shock programmer material. The accuracy of the simulation program (i.e., LS-Dyna) is verified by performing the drop shock test of theon the three types of lead shock programmer with three types. The results of the time history on the test table acceleration between the simulation and the test are compared with those of the shock test and the simulation. The shock test and simulation results are plotted using the tolerance range of the saw-tooth shock wave presented in MIL-STD-810G. The saw-tooth shock wave generated using the lead shock programmer with conical and truncated conical shape is estimated using the verified simulation program. The aspect ratio of the conical and truncated conical lead shock programmer is presented to generate the saw-tooth shock wave is also presented.

This paper presents the LAser Shock Adhesion Test (LASAT) using symmetrical laser shocks. The study is part of ComBoNDT European project that develops new Non-Destructive Tests (NDT) to assess adherence properties of bonded composite structures. The technique, its principle, and the experimental setup are first presented. To evaluate the technology, a various contaminated CFRP assemblies are tested using the LASAT. For each case, their bonding strength is discriminated from a reference bonding strength. If the results are promising, they also rise a lot of questions concerning the state of the material post laser shot. A series of photomicrographs of tested areas are performed showing how the contamination impacts the crack propagation pattern. The study concludes on the technology capability to differentiate a correct assembly from a contaminated one.

Optical telescopes are the most intriguing investigative instruments used for astrometric monitoring and for investigation of celestial objects. Literature presents several investigations concerning the expected imaging performance of optical telescopes and sources of influence which can affect the obtained image quality. In fact its features can drastically decrease in presence of induced vibrations, kinetic movements and mechanical shock, which can come from external sources (i.e. ambient disturbance) or internal signals (i.e. working conditions of the telescope). It should be noted that in the perspective to predict vibrations level which could affect the device, several solutions have been proposed in literature by using wind-tunnel tests (to emulate ambient effects), fluid-dynamic analysis, simulations, shock test, etc. However, very often, these methods implies approximations in terms of induced vibrations as respect the real scenario. In this context, we present here measurements campaigns to study the real kinetic influences which affect a telescope and to analyze the most critical points where these movements are applied. The analyses here conducted arouse interest during the design and the mounting of the instrument and also in order to design specific active compensations, mechanical filters, feedback control and helpful for real-time vibration corrections. In the present study, several types of induced movements will be accounted through 3D measurements and considerations in terms of impressed accelerations.

Mounts for shipboard equipment in naval ships play an important role for vibration and shock suppression. New large-capacity resilient mounts, SDR-D30 and SDR-D45, have been developed. This paper involves performance tests for the mount which have maximum load of 30 kN and 45 kN, respectively. The performance tests have been carried out for several mounts based on military standards, such as MIL-M-19863D(SH), MIL-M-21693C(SH), MIL-M-17508F(SH), and MIL-S-901D(NAVY). The test items consist of deflection at upper rate load test, dynamic stiffness, uniformity, static load-deflection(axial, transverse and longitudinal), drift test, fatigue test, and shock test. From these performance tests, it is confirmed that the two mounts have good performances based on military standards.

This paper presents a procedure of determining the causes of increased vibration of a fan plant and its support structure in the PUC 'Subotička toplana'. Excessive vibrations were observed following the installation of the frequency converter, thus a methodological approach of testing-analysis-diagnosis has been applied. Based on the definition of the causes of this problem, the paper also suggests possible repair procedures.

Both analyses of the damage boundary and shock response spectrum (RSR) are the basis for the development of the protective packaging system. The shock analysis through lab test and numerical simulation found that the root cause of packaging failure was due to the stress of the critical component beyond the yield limit of the material. Lab shock test data showed that the packaging design based on the damage boundary is conservative, and the RSR could be helpful and provide support to develop more effective packaging system. Furthermore, numerical simulation can accurately analyze the component and the entire product packaging system in great detail.

Article history: Received October 6, 2014 Accepted 2 February 2015 Available online 2 February 2015 In this research, the influences of modal properties of a micro cubic satellite on equivalent static loads (due to combination of quasi-static and dynamic loads during launch time) have been studied. The study shows that the magnitude of equivalent static loads can be affected by satellite effective modes and effective mass distribution along natural frequencies. Besides, when to distinct launchers with different dynamic environments candidate for launch, analytical results illustrate that sometimes the equivalent static combined load value can be higher for the launcher with smaller quasi-static loads. This phenomenon is due to effective modal mass distribution of the satellite. Consequently, a higher combined load may be occurred during launch for smaller quasi-static conditions. Furthermore, in separation phase of satellite from the launcher, the satellite modal parameters influence the magnitude of applied shock load in both axial (launch) and lateral directions, importantly. Thus the present study yields reliable input values for separation shock test which considers dynamic properties of the satellite in comparison with some standards and launcher manuals, suggest a rough estimation of shock load, neglecting the satellite structure dynamic behavior. © 2015 Growing Science Ltd. All rights reserved.

In this study, an anaerobic baffled reactor (ABR) with seven chambers was applied to treat medium-strength synthetic industrial wastewater (MSIW). The performance of startup and shock test on treating MSIW was investigated. During the acclimation process, the chemical oxygen demand (COD) of MSIW gradually increased from 0 to 2,000 mg L

The particular study case in this thesis is the shock test performed on the LISA Pathfinder satellite conducted in a laboratory environment on a dedicated test bed: Vega Shock Test Apparatus (VESTA). This test is considered fully representative to study shock levels produced by fairing jettisoning event at Vega Launcher Vehicle, which induces high shock loads towards the satellite. In the frame of this thesis, some transient response analyses have been conducted in MSC Nastran, and a shock simulation tool for the VESTA test configuration has been developed. The simulation tool is based on Nastran Direct Transient Response Analysis solver (SOL 109), and is representative of the upper composite of Vega with the LISA Pathfinder coupled to it. Post-processing routines of transient response signals were conducted in Dynaworks which served to calculate Shock Response Spectra (SRS). The simulation tool is a model of forcing function parameters for transient analysis which adequately correlates with the shock real test data, in order to understand how the effect of shock generated by the launcher is seen in the satellite and its sub-systems. Since available computation resources are limited the parameters for analysis were optimised for computation time, file size, memory capacity, and model complexity. The forcing function represents a release of the HSS clamp band which is responsible for fairing jettisoning, thus the parameters which were studied are mostly concerning the modelling of this event. Among many investigated, those which visibly improved SRS correlation are radial forcing function shape, implementation of axial impulse, clamp band loading geometry and refined loading scheme. Integration time step duration and analysis duration were also studied and found to improve correlation. From each analysis, the qualifying shock environment was then derived by linear scaling in proportion of the applied preload, and considering a qualification margin of 3dB. Consecutive tracking of structural responses along shock propagation path exposed gradual changes in responses pattern and revealed an important property that a breathing mode (n = 0) at the base of a conical Adapter translates into an axial input to the spacecraft. The parametrisation itself was based on responses registered at interfaces located in near-field (where the clamp band is located and forcing function is applied) and medium-field with respect to the shock event location. Following shock propagation path, the final step was the analysis of shock responses inside the satellite located in a far-field region, which still revealed a very good correlation of results. Thus, it can be said that parametrisation process was adequate, and the developed shock simulation tool can be qualified. However, due to the nature of shock, the tool cannot fully replace VESTA laboratory test, but can support shock assessment process and preparation to such test. In the last part of the thesis, the implementation of some finite element model improvements is investigated. Majority of the panels in spacecraft interior exhibited shock over-prediction due to finite element model limitation. Equipment units modelled as lump masses rigidly attached with RBE2 elements to the panel surface are a source of such local over-predictions. Thus, some of the units were remodelled and transient responses were reinvestigated. It was found that remodelling with either solid elements, or lump mass connected to RBE3 element and reinforced by RBE2 element, can significantly improve local transient responses. This conclusion is in line with conclusions found in ECSS Shock Handbook.

The feasibility of applying bio-augmentation tactics to remit the influence of transient oxytetracycline (OTC) shock on the anaerobic ammonium oxidation (ANAMMOX) process was evaluated. The bio-augmentation was applied together with shock test, with OTC shock concentration of 518 mg L−1 and 1-h duration. 0.655–2.62 g volatile suspended solid (VSS) sludges were varied to optimize bio-augmentation dosage (BAD), and appropriate bio-augmentation time (BAT) was determined. The validity of the bio-augmentation was indicated by recovery performance and sludge characteristics. The restoring time of 38 h for bio-augmented reactor was shorter than that of non-bio-augmented reactor (45 h), and heme c content was increased respectively from 0.195 ± 0.001, 0.267 ± 0.047, 0.301 ± 0.049, to 0.340 ± 0.053 μmol g−1 VSS with the BAD of 0.655, 1.31, 1.97, 2.62 g-VSS. The results suggest that bio-augmentation enhances the recovery of ANAMMOX performance following OTC shock and BAT and BAD are key operational factors.

It is not unusual for portable devices to be damaged when they are accidentally dropped on hard floors. Shock tests are increasingly being used to evaluate the drop impact response of portable devices. However, the underlying failure mechanisms have not been fully theoretically explored. There are two candidate failure mechanisms that can account for the drop impact fragility of the display in a smart mobile phone during a shock test: weakest link failure and cumulative damage failure. The weakest link theory provides a basis on a Weibull distribution and the cumulative damage theory on an inverse Gaussian distribution. This article proposes a discrimination procedure for the two distribution types. The probability of correct selection is computed using asymptotic results on the ratio of the Maximum Likelihood (ML) to discriminate between the two distributions. Expressions are provided that can be used to compute the asymptotic distributions of ML estimators or their functions when there is model mis-spec...

Development of small satellites (50kg or less) is undergoing all over the world. Regardless its size, any satellite has to be tested for space environment. Various environment tests, such as vibration, vacuum, low and high temperature are necessary. Especially, shock test is one of the most difficult tests. The shock test needs to satisfy the SRS (shock response spectrum) requirement imposed by the launcher. If the SRS obtained in the test does not exceed the SRS requirement level, the test is invalid. At the same time, the SRS level as low as possible while satisfying the requirement is desired to protect the satellite from the overstress. SRS obtained by an air-gun type shock machine was analyzed using a commercial finite element code (LS-DYNA) to investigate the SRS at low frequencies, 100 to 300Hz, which is very difficult to control in the actual test. The analysis showed that controlling the friction of the slide table is effective to change the slope of SRS at the low frequencies. The lower the friction, the higher slope of SRS is obtained.

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.

The vibration characteristics of railway vehicles are very complex because they are not only dependent on vehicle and track conditions but also on operating conditions. Vibration can cause the failure of rolling stock equipment. To verify that the quality of rolling stock equipment is acceptable, it should be able to withstand vibration tests of reasonable magnitude and duration. There are many standards for vibration and shock tests of equipment in Korea. In this paper, we have reviewed and compared the standards (KS R 9144, R 9146 and IEC 61373) for vibration and shock tests.

Investigation of seal performance is of utmost importance for the development of hydraulic seals especially those employed in high pressure applications and subjected to shock loading. Over the years many apparatus and methods have been adopted to experimentally investigate the seal performance in terms of leakage, friction and wear with one or other limitations. This article describes the design and development of a test rig, which can experimentally assess the performance of reciprocating hydraulic seals. This test rig has features to study experimentally the contact mechanics phenomena at sealing interface and verify theoretical results thus can support development of a sealing system for shock loading applications which involves high pressures of the order of 1000 bar. The test rig is in line with ISO standard but equipped with added features to cater to high pressure & shock test and test of rotary seals.

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.

The common failure modes and failure mechanisms of multilayer chip inductors were studied and a detailed study on the open-circuit failure mechanism, the short-circuit failure mechanism and the mechanism of poor tinning was made in this paper. Then some prevention and improvement measures were given. At last, combined with the pulse current test, the temperature shock test, the resistance to soldering heat and the resistance to dissolution of metallization test, the experiments results indicated that the relevant failure mechanisms were correct.

In this study, the reliability of the traditional equivalent drop theory for transport packaging was experimentally evaluated, and a new physical model that considers the factor of friction was proposed. Using this new model, mathematical shock response equations of a shock test and a test at free-fall were deduced. In addition, a correcting condition was reached. To let the equivalent free-fall height be exactly equivalent, a new friction equivalent drop theory was proposed. This theory not only significantly reduces experimental errors and improves the accuracy of equivalent experiments but also provides a new theoretical basis for experimental analysis of structural cushioning materials. Copyright © 2012 John Wiley & Sons, Ltd.

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.