Pre-test Simulations Research Articles

Mastering Sedation and Associated Respiratory Events through Simulation-Based Training: A Randomised Controlled Trial Involving Non-Anaesthesiology Residents.

Non-anaesthetists commonly administer procedural sedation worldwide, posing the risk of respiratory events that can lead to severe complications. This study aimed to evaluate whether simulation-based learning could lead to enhancements in the clinical proficiency of non-anaesthesiology residents in managing sedation and related respiratory complications. Following the evaluation of baseline clinical performance through a pre-test simulation, 34 residents were randomly allocated to either participate in an innovative simulation-based learning module (intervention group) or view a brief self-learning video (control group). After a one-month period, their clinical performance was assessed again in a post-test simulation involving respiratory arrest during procedural sedation. Two independent assessors rated each resident's performance using video recordings and a scoring tool with scores ranging from 0 to 19/19. The two assessments were averaged for each performance, and the pre- to post-test change was calculated for each resident. While baseline clinical performance was similar, mean (SD) increase in clinical performance was significantly greater in the intervention group than in the control group (+2.4 (1.6) points versus +0.8 (1.3) points, respectively; p = 0.002). Our simulation-based learning sedation module resulted in the enhanced management of sedation-related complications compared to baseline and minimal self-learning. Simulation-based medical education may offer an effective approach for equipping non-anaesthesiology residents with essential skills to mitigate risks associated with sedation. (ClinicalTrials.gov identifier: NCT02722226).

The impact of tutoring on nursing students' clinical judgment: A quasi-experimental study.

Nurses' lack of clinical judgment often leads to adverse patient outcomes due to failure to recognize clinical deterioration, intervene, and manage complications. Teaching clinical judgment through a nursing process can help nursing students provide safe and competent patient care with improved health outcomes and to pass the National Council Licensure Examination for Registered Nurses (NCLEX-RN). The aim of this study was to examine the effect of tutoring on clinical judgment of undergraduate nursing students utilizing Lasater's Clinical Judgment Rubric (LCJR). This study also compared the clinical judgment of male and female nursing students and students from different semester levels. This quasi-experimental study utilized a single group pretest, posttest design. A convenience sample of n = 40 undergraduate nursing students from the Los Angeles County College of Nursing and Allied Health participated in the study. The participants underwent a pretest simulation, four sessions of the Clinical Judgment Model (CJM)-based tutoring, and a posttest simulation. The posttest clinical judgment scores (35.70 ± 3.6) were significantly different from the pretest scores (25.78 ± 5.20). The tutoring had a significant effect on the clinical judgment of nursing students t(39) = -11.64, n = 40, p < .001, at 95% CI of the mean difference. Enhancing nursing students' clinical judgment is crucial to provide high-quality, safe patient care with improved health outcomes. The CJM-based tutoring is an effective strategy for developing clinical judgment in nursing students. This new teaching approach can train students to critically think, develop clinical judgment, and prepare for the complex healthcare environment. Therefore, nurse educators should focus on integrating clinical judgment into the prelicensure nursing program curriculum as a priority.

Shake-table testing and numerical simulation to select the FRCM retrofit solution for flexure/shear deficient RC frames

This paper presents shake-table and numerical investigations to select a retrofit strategy for reinforced concrete (RC) frame structures using fiber-reinforced cementitious matrix (FRCM) composites. Two FRCM alternatives are investigated, namely polyparaphenylene benzobisoxazole (PBO) and carbon FRCM composites, denoted as ‘P-FRCM’ and ‘C-FRCM’, respectively. The study focuses on implementing the selected retrofit material with spike anchorage systems to delay the debonding failure and addresses different failure modes of RC framing systems, including shear or flexure failure. The first phase of this study involves pre shake-table test (STT) simulation to investigate the effectiveness of the selected retrofit technique in delaying local and global damage states and failure modes. STT campaigns are undertaken in the second phase to assess the seismic performance of framing systems retrofitted with different FRCM materials and verify their fiber-based modeling approach. The verified numerical modeling approach of the retrofit techniques is utilized in the third phase to upgrade a benchmark RC moment-resisting frame (MRF) building. A parametric study involving inelastic pushover analyses (IPAs) and multi-record incremental dynamic analyses (IDAs) is finally conducted to assess the vulnerability of the retrofitted building with different FRCM alternatives. It is concluded that the adopted two retrofit techniques significantly reduced the collapse damage state at the design and maximum considered earthquake intensities by up to 59% and 46%, respectively. Although the P-FRCM composite has 38% higher tensile strength and 76% higher ultimate tensile strain than C-FRCM, it slightly improves the overall seismic performance by up to 9% based on the adopted seismic performance index. Owing to the higher cost of P-FRCM compared with its counterpart, a performance-to-cost index confirmed that the C-FRCM composite is the preferred retrofit technique for MRF structures.

Pre-test simulation and a scoping test for dryout and remelting phenomena of an in-vessel debris bed

The present study is intended to investigate the dryout and remelting phenomena of a debris bed during the late phase of an in-vessel severe accident progression. The SIMECO-2 facility at KTH is adapted to conduct the experimental investigation. For selection of an appropriate debris bed in the facility, pre-test simulations are performed by using the COCOMO code to determine: (i) simulant materials of debris particles; (ii) debris bed particle diameters; (iii) configuration and geometry of the debris bed (e.g., shape, layers, dimensions). Candidate particulate beds packed with different mixtures of particles are identified and simulated to obtain their thermal hydraulics in the hemispherical slice test section with radius of 500 mm and width of 120 mm. Based on the simulation results, a particulate bed is chosen and loaded in the SIMECO-2 facility for a scoping investigation. FBG probes with multiple measurement points of each probe are employed to acquire the temperature field of the particulate bed inductively heated. A video recording is applied to detect the dryout and remelting phenomena. In the scoping test, the dryout phenomenon occur first at the elevation of 5 cm from the bed surface under the induction heating power of 14.8 kW, which are comparable with the data predicted by the COCOMO code (6 cm from the bed surface under the heating power of 13.8 kW) in the pre-test simulations.

Numerical simulation of natural convection and heat transfer in a molten pool with embedded cooling tubes

This study described the natural circulation and heat transfer of a molten pool in a specifically designed core catcher conceived for a pressurized water reactor. In addition to external cooling, the core catcher features internal cooling tubes embedded in the molten pool. To investigate the coolability in such a configuration, first, a full-scale core catcher simulation is conducted to give a preliminary study under a real SA situation. Results illustrated that cooling efficiency can be remarkably enhanced due to the inner tubes. Then a test facility of the 2D slice with the geometrical scaled factor of 1:4 has been developed, and molten salt (NaNO3–KNO3) experiments will be implemented in the near future. This study also performed a pre-test simulation using molten NaNO3–KNO3 as a stimulant to study the heat transfer and flow characteristics of the salt pool. The melt convection in the test section was represented by a two-dimensional mesh with a WMLES turbulence model using the FLUENT code. The simulation captured the heat transfer enhancement by the cooling tubes as expected, and the results would help decide the proper test matrix and improvement of instrumentation required to obtain the necessary data for code validation.

Addressing the Lack of Professional Values and Behaviors among New Nurses

Professionalism and safety in patient care are concepts nurses are expected to exhibit in practice. High fidelity simulation was explored to assist in teaching students the behaviors needed to succeed in nursing. Nursing leaders identified areas in which graduates struggle, including critical thinking, skills acquisition, time management, role responsibilities, delegation, and effective communication. The project’s purpose was to analyze students’ perceptions regarding professional nursing values, identify gaps in knowledge concerning professional behavior, and determine perception change of professional values. A pretest post-test simulation intervention was chosen. Improvement in communication and autonomy was noted with statistically significant findings.

Numerical and experimental campaigns for lead solidification modelling and testing

The Computational Fluid-Dynamics (CFD) modelling of Heavy Liquid Metal (HLM) flows in pool configuration is investigated in the framework of the SESAME project. This paper focuses on the coupling between numerical simulations and experimental activity with the objective to make CFD a valid tool in support to the design of safe and innovative Gen-IV nuclear reactors. The attention is focused on the possible occurrence of lead solidification phenomenon. The aim is to demonstrate that the overall modelling of HLM complex systems can include solidification phenomenology by reproducing small/medium scale experiment, making comparison with experimental results, improving the numerical setting (post-test) and evaluating time scales, limitations and computational costs. A dedicated experimental campaign on the SESAME-Stand facility has been performed by the Research Centre Rez (CVR), relying on the use of CFD support, with the specific objective to build a series of datasets suited also for the CFD modelling validation.The numerical simulations of the SESAME-Stand experimental facility performed in STAR-CCM + are described. The model uses liquid lead as working fluid in the pool and air in the cooling channel. By increasing the mass flow rate in the cooling air channel, the solidification process is initiated and the freezing front propagates in the pool until reaching an internal obstacle. The issues encountered in the pre-test simulations have been fully overcome by means of systematic investigations and all the improvements have been applied in the post-test model. A decisive modelling aspect was the correct implementation of the thermal radiation which plays an important role in the cooling process. The numerical model allowed to reach an increased number of initial steady states and accessible transients, according to the experimental matrix. The comparison with the experimental results shows similar temperature configurations and comparable lead frozen fractions in the steady state cases and good agreement in the fast transient solidification-remelting cases.

1966 Structured Teaching to Enhance Laparoscopy Learning

Study Objective To measure the impact of a standardized laparoscopic curriculum on knowledge and simulation skills assessment in Ob/Gyn residents Design Non-Randomized Control Trial Setting Three residency programs in Chicago, IL Patients or Participants Twenty-four residents Interventions A standardized laparoscopic curriculum was developed in accordance with Fundamentals of Laparoscopic Surgery (FLS) training guidelines. The educational program consisted of a didactic lecture with a written pre and post test and laparoscopic simulation training. Residents were trained in peg transfer and precision pattern cutting skills. A skills assessment was administered pre and post simulation training. This skills assessment measured time to completion of peg transfer and time to completion of precision cutting. Data points were assessed using a repeated measures analysis of variance. Measurements and Main Results The residents were evaluated with a significant improvement in knowledge score from 66.7% to 84.4% (p Conclusion Implementing a standardized curriculum improved resident knowledge and simulation skills in laparoscopic techniques. The program demonstrated an improvement in residency learning and could be applied to improve resident training in laparoscopy and FLS training.

Reduced-resolution RANS approach to grid spacer fuel assemblies

One of the main issues in the context of the safety assessment of liquid metal-cooled reactors is flow blockages in fuel sub-assemblies. CFD modelling may be used to predict the temperature and velocity fields inside a fuel assembly under blocked and unblocked conditions. However, the computational cost requirements make it infeasible to model the complete assembly using the resolved RANS, LES or DNS approaches. To this end, a reduced-resolution RANS approach of an assembly is presented and validated in this paper.In order to reproduce and compare with experimental data, the 19-pin hexagonal fuel assembly of the NACIE-UP facility at ENEA in Italy has been selected for the present simulation study. For the flow blockage, a 6-pin edge-type blockage is selected similar to that used in the experimental facility. During the pre-test simulation study, wall-resolved RANS simulations are performed for the unblocked flow conditions. Using the wall-resolved RANS simulations as reference, a mesh sensitivity is performed by subsequently reducing the wall and bulk resolutions. As the blocked flow condition requires transient simulations, the resolution study is only performed for the unblocked flow condition to reduce the computational effort. It is shown that the approach may be used to reproduce the temperature and velocity fields similar to that in wall-resolved simulations within tolerance limits, but at a fraction of the computational cost.Experimental data for unblocked and blocked flow conditions has been made available for the Blocked Fuel Pin Simulator (BFPS) section at the NACIE-UP facility. These experimental data are used to validate the reduced-resolution approach in the post-test analysis. The difference between the present results and the experimental data is attributed for and quantified. Consistent with the literature, two main effects of flow blockages are identified. A local temperature hotspot is observed in the wake of the blockage caused by the coolant recirculation zone. The global effect of temperature peak is observed at the end of the active length downstream of the blockage, caused by the lower mass flow rates in the blocked sub-channels. For the unblocked flow condition, the maximum difference compared to the experimental data is estimated to be 11%. While the error in prediction of the local temperature hotspot and peak temperature at the end of active length is estimated to be 25% and 12%, respectively, for the partially-blocked flow condition. Finally, based on the 19-pin model, the feasibility of the reduced-resolution approach for the complete 127-pin assembly of ALFRED demo reactor is demonstrated. In addition to the unblocked flow condition, the approach is also used for blocked grid spacer conditions. Consistent with the results of NACIE bundle, the two main effects – local and global – of the flow blockage are also observed here. The local effect of temperature hotspot behind the blockage is observed to be dominant for the larger blockage, while the global effect of peak temperature downstream of the blockage is observed to be proportional to the size of the flow blockage.

Inelastic behavior of a bridge bent subjected to truck impact: Experimental and computational study

A unique field experimental study was conducted to investigate the behavior of a reinforced concrete pier bent subjected to impact by a surrogate truck model. The bent was a two-bay, one-story frame that represented a realistic highway structure. It was tested at half scale at the FHWA-FOIL facility. The surrogate truck model consisted of a pendulum with a specially designed impactor that was progressively crushed to represent the impact demands associated with truck collision. The bent was proportioned such that the two exterior columns had different capacities, thereby accommodating two separate tests. After validating the pre-test simulation model using the measured and other experimental data, parametric simulations were conducted to gain insight into the failure response of the bent and to critique the AASHTO truck impact guidelines. The necessity for developing performance-based design guidelines for truck-versus-pier crashes was highlighted.

Pretest Nonlinear Finite-Element Modeling and Response Simulation of a Full-Scale 5-Story Reinforced Concrete Building Tested on the NEES-UCSD Shake Table

A full-scale five-story reinforced concrete building specimen, outfitted with a variety of nonstructural components and systems (NCSs), was built and tested on the Network for Earthquake Engineering Simulation at the University of California, San Diego (NEES–UCSD) large outdoor shake table in the period March 2011–June 2012. The building specimen was subjected to a sequence of dynamic tests including scaled and unscaled earthquake motions. A detailed three-dimensional nonlinear finite-element (FE) model of the structure was developed and used for pretest response simulations to predict the seismic response of the test specimen and for decision support in defining the seismic test protocol and selecting the instrumentation layout for both the structure and NCSs. This paper introduces the building specimen and the shake table test protocol and describes the techniques used for the nonlinear FE modeling and response simulation. Utilized as blind prediction, the pretest simulation results at different scales (global structural level and local member/section/fiber levels) are compared with their experimental counterparts for seismic input (base excitation) of increasing intensity from serviceability to design levels. The predictive capabilities of the used FE modeling techniques are evaluated and possible sources of discrepancies between the FE predictions and experimental measurements are investigated and discussed.

Evaluation of integration methods for hybrid simulation of complex structural systems through collapse

This study examines the performance of integration methods for hybrid simulation of large and complex structural systems in the context of structural collapse due to seismic excitations. The target application is not necessarily for real-time testing, but rather for models that involve large-scale physical sub-structures and highly nonlinear numerical models. Four case studies are presented and discussed. In the first case study, the accuracy of integration schemes including two widely used methods, namely, modified version of the implicit Newmark with fixed-number of iteration (iterative) and the operator-splitting (non-iterative) is examined through pure numerical simulations. The second case study presents the results of 10 hybrid simulations repeated with the two aforementioned integration methods considering various time steps and fixed-number of iterations for the iterative integration method. The physical sub-structure in these tests consists of a single-degree-of-freedom (SDOF) cantilever column with replaceable steel coupons that provides repeatable highlynonlinear behavior including fracture-type strength and stiffness degradations. In case study three, the implicit Newmark with fixed-number of iterations is applied for hybrid simulations of a 1:2 scale steel moment frame that includes a relatively complex nonlinear numerical substructure. Lastly, a more complex numerical substructure is considered by constructing a nonlinear computational model of a moment frame coupled to a hybrid model of a 1:2 scale steel gravity frame. The last two case studies are conducted on the same porotype structure and the selection of time steps and fixed number of iterations are closely examined in pre-test simulations. The generated unbalance forces is used as an index to track the equilibrium error and predict the accuracy and stability of the simulations.

THALLIUM: An experimental facility for simulation of HCLL In-box LOCA and validation of RELAP5-3D system code

The experimental facility THALLIUM (Test HAmmer in Lead LithIUM) was designed to reproduce the hydraulic transient in the HCLL TBS (Helium Cooled Lithium Lead Test Blanket System) breeder loop following the rupture of a Cooling or a Stiffening Plate, i.e. In-box LOCA (Loss Of Coolant Accident). In addition, the facility will be used to validate the simulations of the pressure wave propagation with RELAP5-3D system code. THALLIUM reproduces the geometry of the LLE (Lead Lithium Eutectic) loop of the HCLL TBS and it was installed at the ENEA Brasimone Research Centre. In this paper, the facility is presented in detail, emphasizing the similarities and the differences with the reference HCLL TBS design. Particular attention has been paid to the TBM mock-up and to the TBS Storage/Recirculation Tank, which are the components that required the biggest simplifications among the key components of the facility. An analytical study of the pressure wave was carried out, with the aim to highlight a possible source of inaccuracy that might be displayed in the future simulations with the code. The results of the analytical study show that the fluid-structure interactions will decrease the speed of sound in the LLE. Instead, RELAP5-3D does not consider the fluid-structure interactions and, therefore, a difference between the experimental and the simulation data could arise from the different wave speed. Finally, the RELAP5-3D nodalization and the results of a pre-test simulation are presented. These results proved to be useful for the design of the facility

Resident Education Using a Novel, Low-Cost Postpartum Hemorrhage Simulator With Quantifiable Blood Loss

BACKGROUND: Postpartum hemorrhage is a common and potentially life threatening obstetrical emergency that has shown to be amenable to simulation. METHODS: Fourth year OB/GYN residents participated in a standardized simulation scenario of management of a PPH, prior to and after an educational intervention. The scenario used a novel simulator that quantifies blood loss and was built from low-cost, readily available materials. Residents then underwent an educational debriefing including instruction on PPH management and quantified feedback from their performance during the pretest simulation. Two months later, residents underwent posttesting using a similar PPH simulation. Statistical analysis used paired t test with P-value of less than .05 considered significant. RESULTS: Seven residents completed the pilot study. After the educational debriefing, residents performed corrective interventions earlier in the hemorrhage scenario. The primary outcome, total blood loss at the time of decision to perform exploratory laparotomy, significantly decreased 23% from 2,271 mL on pretest as compared to 1,743 mL on posttest simulation (P=.03). The residents' ability to accurately estimate blood loss improved, however this trend did not reach statistical significance (P=.15). DISCUSSION: Simulation training using this novel, low-cost PPH simulator allows for blood loss at the time of interventions to be accurately recorded and used in educational debriefings. Debriefing using management guidelines and quantified information on resident performance improved resident performance on follow up testing at 2 months.

Comparison of different coupling CFD–STH approaches for pre-test analysis of a TALL-3D experiment

The system thermal-hydraulic (STH) code ATHLET was coupled with the commercial 3D computational fluid dynamics (CFD) software package ANSYS CFX to improve ATHLET simulation capabilities for flows with pronounced 3D phenomena such as flow mixing and thermal stratification. Within the FP7 European project THINS (Thermal Hydraulics of Innovative Nuclear Systems), validation activities for coupled thermal-hydraulic codes are being carried out. The TALL-3D experimental facility, operated by KTH Royal Institute of Technology in Stockholm, is designed for thermal-hydraulic experiments with lead-bismuth eutectic (LBE) coolant at natural and forced circulation conditions. GRS carried out pre-test simulations with ATHLET–ANSYS CFX for the TALL-3D experiment T01, while KTH scientists perform these analyses with the coupled code RELAP5/STAR CCM+. In the experiment T01 the main circulation pump is stopped, which leads to interesting thermal-hydraulic transient with local 3D phenomena. In this paper, the TALL-3D behavior during T01 is analyzed and the results of the coupled pre-test calculations, performed by GRS (ATHLET–ANSYS CFX) and KTH (RELAP5/STAR CCM+) are directly compared.

Board #128 - Research Abstract Comparison of Instructor-led versus Peer-led Debriefing among Nursing Students (Submission #8781)

Hypothesis Debriefing provides students with the opportunity to reflect on their simulation experience in relation to practice.1,2 Although instructor-led debriefing is considered the gold standard5, this needs further inquiry as results from studies are mixed and inconsistent.3,4,5 Approaches like self-debriefing and peer-debriefing or use of multimedia resources that do not require the presence of a facilitator may be a more cost-effective alternative to video-facilitated instructor debriefing6. Despite widespread support, there is little evidence to support the efficacy of the best simulation-based debriefing method. The purpose of this study was to compare the effects of peer-led (PL) debriefing compared with instructor-led (IL) debriefing among nursing students. Such research will inform and support faculty and facilitators in strategies for the promotion of learning through reflection in post-simulation debriefing. Methods This was a non-equivalent control group pretest-posttest design study. A convenience sample of 65 second-year nursing students enrolled in two-week clinical placement rotation in an intensive care unit was randomly assigned to the IL debriefing group (Group A, n = 36) or PL debriefing group (Group B, n = 29). For Group A, after completion of the pretest simulation, an experienced instructor led the debriefing session for participants to reflect on their performances. Printouts from the manikin’s SkillReporter7 and the video recording were used to reflect and analyze students’ actions. The instructor used a standardized debriefing process8 to lead the discussions about the quality of CPR skills and algorithm. Group B underwent PL debriefing, which included two participants comparing their performance with a structured adult BLS video. After the debriefing sessions, the CPR psychomotor skills of both groups were reassessed to identify any differences between the two groups. Results Descriptive statistics and t tests were calculated to summarize the quantitative data using SPSS version 21.0 program. Group differences at each testing interval were analyzed using independent samples t tests. A significance level of p=.05 was chosen. Mean difference of total penalty score in quality of cardiopulmonary resuscitation skills was significantly lower in IL debriefing group than PL group (t = 3.779, p = < .001), that means IL group performed better than PL group. The mean score of satisfaction with simulation experience in IL group was significantly higher than those of PL group (t = 2.698, p = .009). Overall, mean score of quality of debriefing was significantly higher in IL group compared to PL group (t = 4.068, p < .001). Conclusion IL debriefing is an effective method in improving skills performance, and inducing favorable satisfaction, and quality of debriefing among nursing students. This study reports students’ preference for IL debriefing in light of effectiveness, reflective practice, and feedback to participants. Although satisfaction with clinical reasoning and clinical learning was similar in both groups, the quality of subsequent CPR psychomotor skills assessed by raters and data from the simulator, and self-reported satisfaction with simulation and quality of debriefing was higher in the IL group than the PL group. As simulation grows within undergraduate nursing programs, there remains a need to establish the effects of PL debriefing as a possible alternative or addition to the curricula. The impact of the level of student experience, for example final year versus more junior students, needs to be determined if PL debriefing is to be accepted as a viable option within undergraduate nursing education.

Comparison of CFD simulations on two-phase Pressurized Thermal Shock scenarios

Small Break Loss of Coolant Accident (SB LOCA) is one of the most severe transients which may lead to Pressurized Thermal Shock (PTS) on the Reactor Pressure Vessel (RPV) wall. During postulated SB LOCA Emergency Core Cooling (ECC) water is injected into the cold leg, where it mixes with the hot coolant. The mixture of cold and hot coolants flows toward the downcomer. Knowledge of transient temperature distribution in the downcomer is necessary to predict thermal gradients in the structural components of the RPV wall. For the prediction of the temperature fields and heat transfer coefficient between the fluid and wall in the cold leg and the downcomer, reliable computational fluid dynamics (CFD) simulations are needed. To validate CFD models for two-phase PTS scenarios numerical simulations of the TOPFLOW-PTS experiments were performed in the framework of the EU NURISP (NUclear Reactor Integrated Simulation Project) project. The paper presents the post-test CFD simulations of a steady-state TOPFLOW-PTS air/water experiment and the pre-test blind simulations of a steady-state TOPFLOW-PTS steam/water case with condensation. CFD simulations were performed with ANSYS FLUENT, ANSYS CFX and NEPTUNE_CFD. The simulations of the air/water test have shown that correct modeling of the ECC jet behavior is essential for the temperature prediction in the cold leg. For modeling these two-phase flows with rather smooth large free surfaces, Reynolds Averaged Navier–Stokes approach seems to be appropriate. The pre-test simulations of steam/water flow predicted a thermal stratification at the entrance of the downcomer. Finally, the simulations of the TOPFLOW-PTS experiments have depicted considerable differences between the codes and the models.

A comparison of 200 kN magneto-rheological damper models for use in real-time hybridsimulation pretesting

Control devices can be used to dissipate the energy of a civil structure subjected todynamic loading, such as earthquake, wave and wind excitation, thus reducing structuraldamage and preventing failure. The magneto-rheological (MR) fluid damper isa promising device for use in civil structures due to its mechanical simplicity,inherent stability, high dynamic range, large temperature operating range, robustperformance, and low power requirements. The MR damper is intrinsically nonlinearand rate dependent. Thus a challenging aspect of applying this technology is thedevelopment of accurate models to describe the behavior of such dampers forcontrol design and evaluation purposes. In particular, a new type of experimentaltesting called real-time hybrid simulation (RTHS) combines numerical simulationwith laboratory testing of physical components. As with any laboratory testing,safety is of critical importance. For RTHS in particular the feedback and dynamicinteraction of physical and numerical components can result in potentially unstablebehavior. For safety purposes, it is desired to conduct pretest simulations wherethe physical specimen is replaced with an appropriate numerical model yet thenumerical RTHS component is left unchanged. These pretest simulations require aMR damper model that can exhibit stability and convergence at larger fixedintegration time steps, and provide computational efficiency, speed of calculation, andaccuracy during pretest verification of the experimental setup. Several models for MRdampers have been proposed, including the hyperbolic tangent, Bouc–Wen, viscousplus Dahl and algebraic models. This paper examines the relative performance offour MR damper models of large-scale 200 kN MR dampers as needed for pretestsimulations of RTHS. Experimental tests are conducted on two large-scale MRdampers located at two RTHS test facilities at the Smart Structures TechnologyLaboratory at the University of Illinois at Urbana Champaign and the LehighUniversity Network for Earthquake Engineering Simulation facility. It is shown thateach of the MR damper models examined has relative merits and the ultimateselection of the particular model is dependent on the specific RTHS being tested.

On the use of hydrogen in confined spaces: Results from the internal project InsHyde

The paper presents an overview of the main achievements of the internal project InsHyde of the HySafe NoE. The scope of InsHyde was to investigate realistic small-medium indoor hydrogen leaks and provide recommendations for the safe use/storage of indoor hydrogen systems. Additionally, InsHyde served to integrate proposals from HySafe work packages and existing external research projects towards a common effort. Following a state of the art review, InsHyde activities expanded into experimental and simulation work. Dispersion experiments were performed using hydrogen and helium at the INERIS gallery facility to evaluate short and long term dispersion patterns in garage like settings. A new facility (GARAGE) was built at CEA and dispersion experiments were performed there using helium to evaluate hydrogen dispersion under highly controlled conditions. In parallel, combustion experiments were performed by FZK to evaluate the maximum amount of hydrogen that could be safely ignited indoors. The combustion experiments were extended later on by KI at their test site, by considering the ignition of larger amounts of hydrogen in obstructed environments outdoors. An evaluation of the performance of commercial hydrogen detectors as well as inter-lab calibration work was jointly performed by JRC, INERIS and BAM. Simulation work was as intensive as the experimental work with participation from most of the partners. It included pre-test simulations, validation of the available CFD codes against previously performed experiments with significant CFD code inter-comparisons, as well as CFD application to investigate specific realistic scenarios. Additionally an evaluation of permeation issues was performed by VOLVO, CEA, NCSRD and UU, by combining theoretical, computational and experimental approaches with the results being presented to key automotive regulations and standards groups. Finally, the InsHyde project concluded with a public document providing initial guidance on the use of hydrogen in confined spaces.

A procedure for the simulation of failure in thermoplastic composites

Abstract Crash simulation with engineering composites like “glass mat reinforced thermoplastic” (GMT) is still a challenging task, mainly because these materials soften when their ultimate strength is exceeded. This causes the localization of strain, an instability that can only be modeled with finite elements when some kind of regularization technique is applied. This paper addresses the problem of regularization as well as some other relevant problems that occur when the crash of parts built from randomly reinforced plastics such as GMT have to be simulated. Pragmatic solutions are presented and combined to form a procedure for the simulation of the dynamic failure of GMT components consisting of four steps: a regularization technique to prevent the mesh dependence of the simulation results, a way to account for the scatter in the material properties of these materials, a simple representation of the strain rate dependence of the material properties and finally some instructions for the modeling of all relevant details of the geometry of the crashed structure. The final comparison of the results of pre-test simulations with the results of crash tests shows a good correspondence and therefore confirms the proposed approach.