Nonlinear Integrated Simulation of Dropped Container Impact With Platform Deck

2020 ◽  
Author(s):  
Zhenhui Liu ◽  
Ragnar Igland ◽  
Ivar Holta
Keyword(s):  
Plastic Strain ◽  
Failure Mechanism ◽  
High Stress ◽  
Steel Structure ◽  
Experimental Tests ◽  
Failure Criteria ◽  
Offshore Structures ◽  
Tensile Fracture ◽  
Integrated Simulation ◽  
The Impact

Abstract Dropped objects are an important hazard for offshore structures. Depending on the impact energy level, significant plastic deformation may happen. In order to capture the failure mechanism correctly, proper numerical settings shall be used. This paper presents a numeric study for an offshore platform deck encounter potential dropped container impacts. Abaqus Explicit solver was used in this study. One challenge in such kind of analysis is to have a correct tensile fracture model to capture the steel failure mechanism within Abaqus and be in compliance with relevant regulation standards/codes. The steel structure is normally discretized by a certain size of quadrilateral or triangular shell elements. High stress concentration and complicated stress states exist in the impact area. Triaxiality based failures were proposed and used in the study. A calibration against experimental tests has been performed to check the validity of different stress state dependent failure criteria (the RTCL based and the 1st principle plastic strain based). It is concluded that the 1st principle plastic strain based criterion originated from DNVGL-RP-C208 gives the most conservative results. Discussions have been performed based on the results, which may shed light on similar engineering projects.

Impact of Fiber Metal Laminates - Literature Research

2020 ◽  
Vol 22 (4) ◽  
pp. 1355-1370
Author(s):  
Bartłomiej Lisowski
Keyword(s):  
Experimental Tests ◽  
Failure Criteria ◽  
Low Velocity Impact ◽  
General Idea ◽  
Tensile Fracture ◽  
Low Velocity ◽  
Fiber Metal Laminates ◽  
Basic Parameters ◽  
Fiber Metal ◽  
Composite Contact

AbstractThe paper refers the general idea of composite materials especially Fiber Metal Laminates (FMLs) with respect to low-velocity impact incidents. This phenomenon was characterized by basic parameters and energy dissipation mechanisms. Further considerations are matched with analytical procedures with reference to linearized spring-mass models, impact characteristics divided into energy correlations (global flexure, delamination, tensile fracture and petaling absorbed energies) and set of motion second order differential equations. Experimental tests were based on analytical solutions for different types of FML - GLARE type plates and were held in accordance to ASTM standards. The structure model reveals plenty of dependences related to strain rate effect, deflection represented by the correlations among plate and intender deformation, separate flexure characteristics for aluminium and composite, contact definition based on intender end-radius shape stress analysis supported by FSDT, von Karman strains as well as CLT. Failure criteria were conformed to layers specifications with respect to von Misses stress-strain criterion for aluminium matched with Tsai-Hill or Puck criterion for unidirectional laminate. At the final stage numerical simulation were made in FEM programs such as ABAQUS and ANSYS. Future prospects were based on the experiments held over 3D-fiberglass (3DFG) FMLs with magnesium alloy layers which covers more favorable mechanical properties than FMLs.

scholarly journals Experimental research of the impact of upper reinforcement on the tension membrane action of narrow three-span reinforced concrete slabs

2020 ◽  
Vol 310 ◽  
pp. 00056
Author(s):  
Miroslaw Wieczorek
Keyword(s):  
Reinforced Concrete ◽  
Failure Mechanism ◽  
Experimental Research ◽  
Experimental Tests ◽  
Concrete Slabs ◽  
Membrane Action ◽  
Experimental Stand ◽  
Reinforced Concrete Slabs ◽  
Reinforced Steel ◽  
The Impact

The aim of the paper was to demonstrate the influence of reinforced steel parameters and quantity on the failure mechanism of four three-span models of reinforced concrete strips with the dimensions 7140×500×190 mm. Two models had only bottom reinforcement, while two were reinforced at the bottom and upper sides. The paper contains the description of the experimental stand and models along with the results of experimental tests which were compared with the results of the calculations based on traditional methods.

Failure mechanism of Ω-shape 3D orthogonal woven composite component under transverse low-velocity impact and subsequent axial compression load

2021 ◽  
pp. 105678952110365
Author(s):  
Zhongxiang Pan ◽  
Mingling Wang ◽  
Zhiping Ying ◽  
Xiaoying Cheng ◽  
Zhenyu Wu
Keyword(s):  
Failure Mechanism ◽  
Damage Zone ◽  
High Stress ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Complex Deformation ◽  
Velocity Impact ◽  
Compression After Impact ◽  
Impact Side ◽  
The Impact

Failure mechanism of complex profile component is always different from that of conventional plate counterpart due to the coupling effect of material and structure. In this work, the low-velocity impact (LVI) and compression after impact (CAI) behaviors of Ω-shape hybrid carbon/Kevlar 3 D orthogonal woven (3DOW) composite made for vehicle B-pillar were comprehensively studied by mechanical tests and mesoscale finite element (FE) analysis at component level, high-speed infrared (IR) thermal imaging, acoustic emission (AE) detection, and microscopic damage morphology characterization. It is found that a through-thickness stress concentration ring leads to high stress state and damage zone penetrating from the impact side to non-impact side along the ring path instead of at the lowest impactor position. The slope effect can not only help the stress conduction downward, but also inhibit the damage propagation from the impact side to the slope. Impact-induced cracks are concentrated around the R corners and extended along the axial direction of the specimen, forming the strip-shaped damage concentration zone along the upper eave of the slope. The Progressive Top-Down Crushing (PTDC) mode of compression after impact is due to the complex deformation process of each yarn such as squeezing, folding and eversion in the crushing process from the top of specimen. And the Middle Indentation Fracture (MIF) mode is the result of bending instability and abrupt fracture. This work presents a reference significance for the further development of composite strengthening components in vehicle bodywork.

scholarly journals Investigation on the Failure Mechanism of Weak Floors in Deep and High-Stress Roadway and the Corresponding Control Technology

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1408
Author(s):  
Dong Zhang ◽  
Jianbiao Bai ◽  
Shuai Yan ◽  
Rui Wang ◽  
Ningkang Meng ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Support System ◽  
Impact Damage ◽  
High Stress ◽  
Field Tests ◽  
Energy Conditions ◽  
Mining Operations ◽  
Static Loads ◽  
Floor Heave ◽  
The Impact

Large deformation of roadway and floor burst are the two major geotechnical hazards encountered with high mining stress in deep mines. In this paper, the stress and energy conditions generated by the impact damage on the rock surrounding a roadway are analyzed, and UDEC software was used to study the deformation characteristics of the roadway, as well as its failure mechanism under the influence of superimposed dynamic and static loads. The results indicate that the soft floor of a deep-buried roadway has a high damage degree and an obvious stress release effect, high static load leads to slow floor heave, and strong dynamic load disturbance is the principal trigger leading to floor burst. In addition, the anisotropy caused by the bedding surface weakens the cooperative characteristics of the support system, resulting in serious instability of the whole rock surrounding the roadway. Full-section anchor cables and inverted arches were adopted to maintain the stability of the rock surrounding the roadway. The monitoring results obtained from field tests show that the adoption of the combined support system effectively avoids floor burst caused by the superposition of dynamic and static loads; the maximum floor heave is 67.9 mm, which is 95% lower than the original value, ensuring safety in coal mining operations.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

Static and dynamic response of sandwich beams with lattice and pantographic cores

2021 ◽  
pp. 109963622110338
Author(s):  
Yury Solyaev ◽  
Arseniy Babaytsev ◽  
Anastasia Ustenko ◽  
Andrey Ripetskiy ◽  
Alexander Volkov
Keyword(s):  
Mechanical Performance ◽  
Lattice Structure ◽  
Unit Length ◽  
Experimental Tests ◽  
Plane Geometry ◽  
Sandwich Beams ◽  
Static Tests ◽  
Three Point Bending ◽  
The Core ◽  
The Impact

Mechanical performance of 3d-printed polyamide sandwich beams with different type of the lattice cores is investigated. Four variants of the beams are considered, which differ in the type of connections between the elements in the lattice structure of the core. We consider the pantographic-type lattices formed by the two families of inclined beams placed with small offset and connected by stiff joints (variant 1), by hinges (variant 2) and made without joints (variant 3). The fourth type of the core has the standard plane geometry formed by the intersected beams lying in the same plane (variant 4). Experimental tests were performed for the localized indentation loading according to the three-point bending scheme with small span-to-thickness ratio. From the experiments we found that the plane geometry of variant 4 has the highest rigidity and the highest load bearing capacity in the static tests. However, other three variants of the pantographic-type cores (1–3) demonstrate the better performance under the impact loading. The impact strength of such structures are in 3.5–5 times higher than those one of variant 4 with almost the same mass per unit length. This result is validated by using numerical simulations and explained by the decrease of the stress concentration and the stress state triaxiality and also by the delocalization effects that arise in the pantographic-type cores.

scholarly journals Experimental and numerical modeling to investigate the riverbank’s stability

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Asad H. Aldefae ◽  
Rusul A. Alkhafaji
Keyword(s):  
Numerical Simulation ◽  
Failure Mechanism ◽  
High Stress ◽  
Physical Models ◽  
Term Condition ◽  
Tigris River ◽  
Soil Settlement ◽  
Failure Angle ◽  
Dangerous Place ◽  
Type Of Failure

AbstractThe purpose of this paper is to assess the failure mechanism of riverbanks due to stream flow experimentally and numerically to avoid recurring landslides by identifying the most dangerous place and treating them by a suitable method. The experiments and the physical models were carried out to study the failure mechanism of riverbank and evaluation of their stability in two cases: short-term condition and long-term condition flow where three models were tested. The Tigris River (Iraq) is considered as a model in this paper in terms of the applied velocity and modeled soil of the banks it was used at the same characteristics in the prototype scale. Also, a numerical simulation was performed using the FLOW-3D program to determine the velocity distribution and to identify the areas subjected to the high stress levels through the water flow. The obtained results in this paper are inspecting of failure mechanism types that occur under the influence of specific limits of flow velocity, which have shown good compatibility with the type of failure in the prototype scale. In addition to calculating the amount of soil erosion, the failure angle, and the amount of soil settlement at the riverbank model is investigated also. The results of experimental work and numerical simulation were well matched, where the standard error rate for Froude number ranged between (1.8%–6.6%), and the flow depth between (2.7%–6.9%).

Failure Mechanism Analysis of Electromagnetic Relay under Mechanical Impact

2013 ◽  
Vol 473 ◽  
pp. 39-45 ◽  
Author(s):  
Guo Wei Zhao ◽  
Yong Chen ◽  
De Yong Li ◽  
Bin Tang
Keyword(s):  
Failure Mechanism ◽  
Magnetic Circuit ◽  
Impact Damage ◽  
Engineering Application ◽  
Air Gap ◽  
Mechanism Analysis ◽  
Mechanical Impact ◽  
Electromagnetic Relay ◽  
Electromagnetic Relays ◽  
The Impact

The aim was to analyze failure mechanism of electromagnetic relay caused by mechanical impact. The principle of electromagnetic relays was studied and the effect of mechanical impact on electromagnetic relays was analyzed in this paper. Based on the established magnetic circuit model, the relationship of the magnetic field strength, the electromagnetic attraction and the impact damage degree was studied. Then, the damage intensity of mechanical impact on magnetic circuit was decided. Afterwards, the structure of electromagnetic relays was improved, and the mechanical impact simulation was studied by ANSYS. The results show that the uncontrollability of electromagnetic relay is mainly caused by air gap, which is aroused by mechanical impact; in addition, the size of air gap is inversely proportional to electromagnetic attraction force. Moreover, the improved structure of relays can increase impact resistance and broaden the scope of engineering application of electromagnetic relay.

Overview of EAF Screening Results on the 900 MWe NPP French Fleet

2016 ◽  
Author(s):  
Thomas Métais ◽  
Nicolas Robert ◽  
Pierre Genette ◽  
Nicolas Etchegaray
Keyword(s):  
Power Plants ◽  
Screening Method ◽  
Experimental Tests ◽  
Degradation Process ◽  
Primary System ◽  
Transfer Coefficients ◽  
Screening Process ◽  
The Usa ◽  
License Renewal ◽  
The Impact

In the wake of numerous experimental tests carried out in air and also in a PWR environment, both abroad and in France, an update of the current thermal fatigue codification is underway in France. Proposals are currently being integrated in the RCC-M code [1]. In parallel, it is necessary to evaluate the impact of codification evolution on the RCS components. In the USA, such evaluations have already been implemented for license renewal to operate power plants beyond their initial 40 years of operation. In order to reduce the scope of the calculations to perform, a preliminary screening was carried out on the various areas of the primary system components: this screening is detailed in an EPRI report [2]. The output of this screening process is a list of locations that are most prone to EAF degradation process and it is on these zones only that detailed EAF calculations are carried out. In France, a similar approach was defined in the perspective of the fourth ten-year visit of the 900 MWe plants (VD4 900 MWe) so as to map out all the locations that are most impacted by EAF and hence concentrate the calculation effort on these specific areas for the VD4 900 MWe. In that respect, a specific methodology to evaluate the factor to account for environmental effects or Fen [3] based on correlations [4] for hot and cold shocks was established. These correlations use data that is readily accessible in transient description documents and stress reports such as temperature change, heat transfer coefficients, ramp duration and geometry. The need for these correlations is specific to the French context due to a need for a preliminary and yet precise idea of the overall impact of the modifications brought to the RCC-M code in fatigue before the VD4 900 MWe. This paper presents the results of the screening method that was applied to the whole RCS of the 900 MWe NPP fleet.

Wave Impact Loads on the Bottom of Flat Decks

2021 ◽  
Author(s):  
Daniel de Oliveira Costa ◽  
Julia Araújo Perim ◽  
Bruno Guedes Camargo ◽  
Joel Sena Sales Junior ◽  
Antonio Carlos Fernandes ◽  
...  
Keyword(s):  
Scale Effects ◽  
Offshore Structures ◽  
Model Tests ◽  
Analytical Models ◽  
Navier Stokes ◽  
Impact Loads ◽  
Wave Impact ◽  
Wave Channel ◽  
Waves And Currents ◽  
The Impact

Abstract Slamming events due to wave impact on the underside of decks might lead to severe and potentially harmful local and/or global loads in offshore structures. The strong nonlinearities during the impact require a robust method for accessing the loads and hinder the use of analytical models. The use of computation fluid dynamics (CFD) is an interesting alternative to estimate the impact loads, but validation through experimental data is still essential. The present work focuses on a flat-bottomed model fixed over the mean free surface level submitted to regular incoming waves. The proposal is to reproduce previous studies through CFD and model tests in a different reduced scale to provide extra validation and to identify possible non-potential scale effects such as air compressibility. Numerical simulations are performed in both experiments’ scales. The numerical analysis is performed with a marine dedicated flow solver, FINE™/Marine from NUMECA, which features an unsteady Reynolds-averaged Navier-Stokes (URANS) solver and a finite volume method to build spatial discretization. The multiphase flow is represented through the Volume of Fluid (VOF) method for incompressible and nonmiscible fluids. The new model tests were performed at the wave channel of the Laboratory of Waves and Currents (LOC/COPPE – UFRJ), at the Federal University of Rio de Janeiro.

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