Response and Failure of Internal Structural Subsystems Under Blast and Shock Loading

1994 ◽  
Vol 116 (4) ◽  
pp. 409-418
Author(s):  
D. W. Tennant ◽  
H. S. Levine
Keyword(s):  
Transient Analysis ◽  
Shock Loading ◽  
Failure Modes ◽  
Three Dimensional ◽  
Structural Response ◽  
Steel Structures ◽  
Structural Components ◽  
Nonlinear Transient ◽  
Potential Failure ◽  
Ground Shock

The objective of this paper is to evaluate the ability to accurately predict the motions, structural response, and failure modes of internal structural components subjected to high-intensity airblast and ground shock loading. The cases of interest involve a surface flush, buried reinforced concrete cylinder that is expected to experience negligible damage, within which are contained aluminum and steel structures that may or may not be shock-isolated at the internal attachment points. The structures and subsystems are modeled in detail using the FLEX three-dimensional nonlinear transient analysis code. The analyses were carried out using the soil island approach to represent the local airblast-induced, direct-induced, and crater-related ground shock from a simulated nuclear explosion. A test involving only local airblast effects with hard-mounted internal substructures was conducted. Comparisons of data from this test with calculations will be presented. Calculations will also be included that show potential failure mechanisms for the internal subsystems and their causes.

Analytical and Experimental Simulation of Fan Blade Behavior and Damage Under Bird Impact

1991 ◽  
Vol 113 (4) ◽  
pp. 582-594 ◽  
Author(s):  
H. C. Teichman ◽  
R. N. Tadros
Keyword(s):  
Impact Analysis ◽  
Failure Modes ◽  
Three Dimensional ◽  
Structural Response ◽  
Analytical Models ◽  
Experimental Simulation ◽  
Experimental Program ◽  
Contact Algorithm ◽  
Bird Impact ◽  
Fan Blade

An extensive analytical and experimental program has been undertaken to investigate the Foreign Object Damage resistance capabilities of external components for small gas turbofan engines. A transient nonlinear impact analysis has been used to predict the structural response of fan blades under bird ingestion conditions. This analysis is based on finite elements, a three-dimensional bird load model, and an interactive structure-to-bird contact algorithm. Experiments were designed and carried out to record large blade deformations during bird impact, and were used to validate and calibrate the analytical models. The analytical models and testing program are described, and dominant fan blade response and failure modes are presented. Predicted results demonstrate good correlation with tests. Analysis application to fan blade design and other engine components is recommended.

scholarly journals Nonlinear numerical simulation of punching shear behaviour of reinforced concrete flat slabs with shear-heads

2019 ◽  
Author(s):  
D.V. Bompa ◽  
A.Y. Elghazouli
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Numerical Models ◽  
Three Dimensional ◽  
Structural Response ◽  
Analytical Models ◽  
Shear Behaviour ◽  
Flat Slabs ◽  
Modes Of Failure ◽  
Concrete Damage

This paper examines the structural response of reinforced concrete flat slabs, provided with fully-embedded shear-heads, through detailed three-dimensional nonlinear numerical simulations and parametric assessments using concrete damage plasticity models. Validations of the adopted nonlinear finite element procedures are carried out against experimental results from three test series. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes, numerical investigations are carried out in order to examine the influence of key material and geometric parameters. The results of these numerical assessments enable the identification of three modes of failure as a function of the interaction between the shear-head and surrounding concrete. Based on the findings, coupled with results from previous studies, analytical models are proposed for predicting the rotational response as well as the ultimate strength of such slab systems. Practical recommendations are also provided for the design of shear-heads in RC slabs, including the embedment length and section size. The analytical expressions proposed in this paper, based on a wide-ranging parametric assessment, are shown to offer a more reliable design approach in comparison with existing methods for all types of shear-heads, and are suitable for direct practical application.

Effect of Bolt Clamping Force and Constraint Arrangement on Structural Strength of Bolted Joint

2016 ◽  
Author(s):  
Jianfeng Mao ◽  
Shiyi Bao ◽  
Luo Lijia ◽  
Zengliang Gao
Keyword(s):  
Failure Modes ◽  
Structural Strength ◽  
Three Dimensional ◽  
Frictional Coefficient ◽  
Structural Behavior ◽  
Clamping Force ◽  
Bolted Joint ◽  
Detailed Model ◽  
Deformation State ◽  
Potential Failure

In this article, the effect of bolt clamping force and constraint arrangement on structural strength of bolted joint was investigated by finite element method (FEM) prior to hardware tests. This study developed a numerical simulation to predict the deformation behavior and detect potential failure modes. In achieving it, a three dimensional (3D) detailed model of bolted joint was constructed. FE dynamic simulation was used to simulate the structural behavior of the bolted joint by gradually applying tension force on the ends. The numerical simulations were conducted with the torque of 0.3N.m, 3.0N.m, 6.0N.m at different tensile levels in several frictional states between contact plates. In order to determine the critical friction force on the plates, three kinetic frictions between bolt and plate hole were employed in the FE calculation to detect the shear stress on the bolt. Finally, the structural behavior of the bolted joint was analyzed in terms of stress distribution, deformation state by varying clamping force and frictional coefficient.

Study about Improving the Quality Process Performance for a Steel Structures Components Assembly Using FMEA Method

2016 ◽  
Vol 822 ◽  
pp. 429-436 ◽  
Author(s):  
Cristina Ileana Pascu ◽  
Daniel Paraschiv
Keyword(s):  
Failure Modes ◽  
Action Plan ◽  
Steel Structures ◽  
Maintenance Program ◽  
Working People ◽  
Potential Failure ◽  
Fmea Method ◽  
Quality Of Products

Analysis of failure modes and effects (FMEA) is a method of analyzing the potential failure of a product or process, to develop an action plan aimed at their prevention and increased quality of products, processes and job production environments. As a method of critical analysis, FMEA has very clear objectives aimed at: determination of the weaknesses of a technical system; initiating causes of failure-seeking components; analysis environmental impacts, safety of operation, the product value; provision of corrective actions to remove the causes of the occurrence of defects; provision of a plan to improve product quality and maintenance; determining the needs of technology and modernization of production; increasing the level of communication between departments working people hierarchical levels. FMEA should be used before taking the product. There is no point subsequently, only because customer demands, to achieve FMEA. Therefore, FMEA must be within organizational conduct. Using timely analysis FMEA - Process avoid costly modifications of the technological achievement assembly "stator Housing" by identifying potential defects, avoidance and risk and potential consequences of faults. We studied the potential causes of defects and have proposed improvements. Among these are: implementing and tracking preventive maintenance program; providing specific compliance welding; acquisition of a specialized table seating and download the blank; purchasing a scarfing machine.

Seismic actions on acceleration sensitive non-structural components in ductile frames

2010 ◽  
Vol 43 (2) ◽  
pp. 110-125 ◽  
Author(s):  
S. R. Uma ◽  
John X. Zhao ◽  
Andrew B. King
Keyword(s):  
Spectral Response ◽  
Limit State ◽  
Structural Response ◽  
Response Spectra ◽  
Ultimate Limit State ◽  
Structural Components ◽  
Floor Response Spectra ◽  
Potential Failure ◽  
Response Amplification ◽  
Floor Acceleration

Earthquake loadings standard NZS 1170.5:2004 has introduced new provisions for the design of building parts and non-structural components. The provisions include factors to define peak floor acceleration up the height of a building, and acceleration response amplifications for components that are quite different from overseas counterparts. In this study, acceleration demands on non-structural components located in ductile frame buildings are analysed under earthquake records from crustal and slab events, for design levels representing ultimate limit state and serviceability limit state. A floor response spectra approach is used to study the demands on non-structural components. It is noted that the peak floor acceleration demands with respect to that of the ground are not amplified up the height of the building to the extent suggested in NZS provisions. The floor response spectra show peaks near the modal periods of the building indicating higher demands on the components with periods closer to the building period. However, NZS provisions fail to include this effect, since the spectral response amplification is defined independent of building period. Spectral demands exceed the NZS provisions at the fundamental periods of the buildings, more significantly at serviceability conditions, indicating potential failure of non-structural components with periods close to the building periods. Following the analytical observations from the buildings considered in this study it is clear that the design provisions for non-structural components should be linked to the structural response for specific performance levels rather than the ‘life-safety’ performance level only that is currently adopted in the New Zealand design standard.

Three-Dimensional Thermohydrodynamic Morton Effect Simulation—Part I: Theoretical Model

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Junho Suh ◽  
Alan Palazzolo
Keyword(s):  
Heat Flux ◽  
Theoretical Model ◽  
Transient Analysis ◽  
Three Dimensional ◽  
Fluid Film ◽  
Integration Scheme ◽  
Morton Effect ◽  
Rotor Bearing ◽  
Nonlinear Transient ◽  
Bearing System

The present study is focused on accurate prediction of the Morton effect problem including journal asymmetric heating and the corresponding long period amplitude oscillations using a nonlinear time transient rotor-dynamic simulation. This paper presents a theoretical model of thermal induced synchronous instability problems in a nonlinear rotor–bearing system, and suggests a new computational algorithm for the nonlinear transient analysis of the Morton effect where the dynamic and thermal problems are combined. For the analysis of the Morton effect problem, a variable viscosity Reynolds equation and a 3D energy equation are coupled via temperature and viscosity, and solved simultaneously. Three-dimensional heat transfer equations of bearing and shaft are modeled by a finite element method, and thermally coupled with the fluid film via a heat flux boundary condition. Asymmetric heat flux into the synchronously whirling rotor is solved by the orbit time averaged heat flux from fluid film to the spinning shaft surface. The journal orbit is calculated by the nonlinear transient dynamic analysis of a rotor–bearing system with a variable time step numerical integration scheme. For the computation time reduction, modal coordinate transformation is adopted in dynamic and thermal transient analysis. Thermal bow effect makes a significant change to the dynamic behavior of a rotor–bearing system, and a thermal hysteresis bode plot, that is one of the characteristics of the Morton effect problem, is presented with time varying spin speed.

Scanning Electron Microscopy in Hybrid Microelectronics

1976 ◽  
Vol 34 ◽  
pp. 456-457
Author(s):  
S. Khadpe ◽  
R. Faryniak
Keyword(s):  
Integrated Circuits ◽  
Thick Film ◽  
Integrated Circuit ◽  
Failure Modes ◽  
Three Dimensional ◽  
Circuit Components ◽  
Hybrid Microcircuit ◽  
Electrical Connections ◽  
Scanning Electron

The Scanning Electron Microscope (SEM) is an important tool in Thick Film Hybrid Microcircuits Manufacturing because of its large depth of focus and three dimensional capability. This paper discusses some of the important areas in which the SEM is used to monitor process control and component failure modes during the various stages of manufacture of a typical hybrid microcircuit.Figure 1 shows a thick film hybrid microcircuit used in a Motorola Paging Receiver. The circuit consists of thick film resistors and conductors screened and fired on a ceramic (aluminum oxide) substrate. Two integrated circuit dice are bonded to the conductors by means of conductive epoxy and electrical connections from each integrated circuit to the substrate are made by ultrasonically bonding 1 mil aluminum wires from the die pads to appropriate conductor pads on the substrate. In addition to the integrated circuits and the resistors, the circuit includes seven chip capacitors soldered onto the substrate. Some of the important considerations involved in the selection and reliability aspects of the hybrid circuit components are: (a) the quality of the substrate; (b) the surface structure of the thick film conductors; (c) the metallization characteristics of the integrated circuit; and (d) the quality of the wire bond interconnections.

Three-Dimensional Reconstruction of Two Forms of the Chaperonin GRO EL

1990 ◽  
Vol 48 (1) ◽  
pp. 258-259
Author(s):  
J.L. Carrascosa ◽  
G. Abella ◽  
S. Marco ◽  
M. Muyal ◽  
J.M. Carazo
Keyword(s):  
Three Dimensional ◽  
The Other ◽  
Two Dimensional ◽  
Series Method ◽  
Three Dimensional Reconstruction ◽  
Structural Components ◽  
E Coli ◽  
Dimensional Reconstruction ◽  
Morphogenetic Factors ◽  
Tilt Series

Chaperonins are a class of proteins characterized by their role as morphogenetic factors. They trantsiently interact with the structural components of certain biological aggregates (viruses, enzymes etc), promoting their correct folding, assembly and, eventually transport. The groEL factor from E. coli is a conspicuous member of the chaperonins, as it promotes the assembly and morphogenesis of bacterial oligomers and/viral structures.We have studied groEL-like factors from two different bacteria:E. coli and B.subtilis. These factors share common morphological features , showing two different views: one is 6-fold, while the other shows 7 morphological units. There is also a correlation between the presence of a dominant 6-fold view and the fact of both bacteria been grown at low temperature (32°C), while the 7-fold is the main view at higher temperatures (42°C). As the two-dimensional projections of groEL were difficult to interprete, we studied their three-dimensional reconstruction by the random conical tilt series method from negatively stained particles.

scholarly journals Compressive behaviours of octet-truss lattices

2020 ◽  
Vol 234 (16) ◽  
pp. 3257-3269 ◽  
Author(s):  
Yifan Li ◽  
Huaiyuan Gu ◽  
Martyn Pavier ◽  
Harry Coules
Keyword(s):  
Failure Modes ◽  
Density Ratio ◽  
Three Dimensional ◽  
Compressive Load ◽  
High Strength ◽  
Detailed Comparison ◽  
Compressive Response ◽  
Beam Elements ◽  
Structural Applications ◽  
Octet Truss

Octet-truss lattice structures can be used for lightweight structural applications due to their high strength-to-density ratio. In this research, octet-truss lattice specimens were fabricated by stereolithography additive manufacturing with a photopolymer resin. The mechanical properties of this structure have been examined in three orthogonal orientations under the compressive load. Detailed comparison and description were carried out on deformation mechanisms and failure modes in different lattice orientations. Finite element models using both beam elements and three-dimensional solid elements were used to simulate the compressive response of this structure. Both the load reaction and collapse modes obtained in simulations were compared with test results. Our results indicate that three-dimensional continuum element models are required to accurately capture the behaviour of real trusses, taking into account the effects of finite-sized beams and joints.

scholarly journals The Hydromechanical Interplay in the Simplified Three-Dimensional Limit Equilibrium Analyses of Unsaturated Slope Stability

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 73
Author(s):  
Panagiotis Sitarenios ◽  
Francesca Casini
Keyword(s):  
Analytical Solution ◽  
Slope Stability ◽  
Slope Failure ◽  
Failure Modes ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Three Dimensional ◽  
Stability Limit ◽  
Smooth Transition

This paper presents a three-dimensional slope stability limit equilibrium solution for translational planar failure modes. The proposed solution uses Bishop’s average skeleton stress combined with the Mohr–Coulomb failure criterion to describe soil strength evolution under unsaturated conditions while its formulation ensures a natural and smooth transition from the unsaturated to the saturated regime and vice versa. The proposed analytical solution is evaluated by comparing its predictions with the results of the Ruedlingen slope failure experiment. The comparison suggests that, despite its relative simplicity, the analytical solution can capture the experimentally observed behaviour well and highlights the importance of considering lateral resistance together with a realistic interplay between mechanical parameters (cohesion) and hydraulic (pore water pressure) conditions.

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