scholarly journals Statical Evaluation Of The Europe Bridge Between Kehl And Strasbourg According To The “Guideline For The Recalculation Of Existing Road Bridges” With Specific Mathematical And Structural Examination Of The Cracks In The Superstructure

2021 ◽  
Author(s):  
Leonhard Oechsle
Keyword(s):  
Crack Formation ◽  
Fatigue Cracks ◽  
Structural Safety ◽  
Fe Model ◽  
Structural Examination ◽  
Load Bearing ◽  
Literature Research ◽  
Fatigue Design ◽  
Static Modelling ◽  
Bearing System

<div>This master´s project re-evaluates the Europe Bridge after 60 years of service. The framework for the calculations is provided by the “Guideline for the Recalculation of Existing Road Bridges”. With the help of a computer model, generated by the program SOFiSTiK, and the prescribed loads of the guideline, the required checks in the ULS were performed at the main load bearing system. As the results indicate a high exceedance of the capacity, different alternatives were evaluated to restore the structural safety.</div><div><br></div><div>A specific focus was laid on the assessment of the cracks in a connection of the lateral load bearing system. Initially, a literature research on the crack formation in the superstructure of steel bridges was conducted. The gathered information points towards category three fatigue cracks that were caused by poor fatigue design and a discrepancy between static modelling and execution on site. These conclusions were confirmed by the fatigue checks of the affected connections. However, an analysis of the crack detail with a FE-model of the lateral system shows that the crack has no significant impact on the load bearing behaviour of other components. </div>

scholarly journals Towards a Methodology for Component Design of Metallic AM Parts Subjected to Cyclic Loading

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 709
Author(s):  
Uwe Zerbst ◽  
Mauro Madia ◽  
Giovanni Bruno ◽  
Kai Hilgenberg
Keyword(s):  
Unsolved Problem ◽  
Fatigue Cracks ◽  
Special Focus ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Lack Of Fusion ◽  
Fatigue Design ◽  
Component Design ◽  
Similar Temperature ◽  
Potential Improvement

The safe fatigue design of metallic components fabricated by additive manufacturing (AM) is still a largely unsolved problem. This is primarily due to (a) a significant inhomogeneity of the material properties across the component; (b) defects such as porosity and lack of fusion as well as pronounced surface roughness of the as-built components; and (c) residual stresses, which are very often present in the as-built parts and need to be removed by post-fabrication treatments. Such morphological and microstructural features are very different than in conventionally manufactured parts and play a much bigger role in determining the fatigue life. The above problems require specific solutions with respect to the identification of the critical (failure) sites in AM fabricated components. Moreover, the generation of representative test specimens characterized by similar temperature cycles needs to be guaranteed if one wants to reproducibly identify the critical sites and establish fatigue assessment methods taking into account the effect of defects on crack initiation and early propagation. The latter requires fracture mechanics-based approaches which, unlike common methodologies, cover the specific characteristics of so-called short fatigue cracks. This paper provides a discussion of all these aspects with special focus on components manufactured by laser powder bed fusion (L-PBF). It shows how to adapt existing solutions, identifies fields where there are still gaps, and discusses proposals for potential improvement of the damage tolerance design of L-PBF components.

Age Dependent and Anisotropic Material Properties of Immature Porcine Sclera

2013 ◽  
Author(s):  
Jami M. Saffioti ◽  
Brittany Coats
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Anisotropic Material ◽  
Computational Models ◽  
Fe Model ◽  
Ocular Tissues ◽  
Load Bearing ◽  
Anisotropic Properties ◽  
Age Dependent ◽  
Testing Protocols

Current finite element (FE) models of the pediatric eye are based on adult material properties [2,3]. To date, there are no data characterizing the age dependent material properties of ocular tissues. The sclera is a major load bearing tissue and an essential component to most computational models of the eye. In preparation for the development of a pediatric FE model, age-dependent and anisotropic properties of sclera were evaluated in newborn (3–5 days) and toddler (4 weeks) pigs. Data from this study will guide future testing protocols for human pediatric specimens.

scholarly journals FEA-Analysis of Shaft and Supports Deformations for Huge Precise Lathe. Statics and Resonances

2018 ◽  
Vol 1 (1) ◽  
pp. 341-348
Author(s):  
Stanislau Dounar ◽  
Alexandre Lakimovitch ◽  
Andrei Ausiyevich ◽  
Andrzej Jakubowski
Keyword(s):  
System Simulation ◽  
Static Stiffness ◽  
Load Bearing ◽  
Machining Forces ◽  
Rotor Shaft ◽  
Fea Analysis ◽  
Bearing System

Abstract Load bearing system simulation is provided for a huge lathe to be renovated. Static and modal analyses are done by FEM. Focus was centerline rising, needed for larger rotor shaft machining. Forces between shaft and three supports were applied. Shaft static stiffness is lowered at 1.15 times only for 600 mm centerline rising. Supports have lost its rigidity at 1.42 times. Concrete pouring into bed cavities is recommended for supports flexibility limitation such as tailstock reinforcement. Robustness of bottom resonances is revealed both for rotor shaft (14.5–18.2 Hz) and supports (42.7–55.4 Hz). Centerline rising is allowed on 300 mm at least. It gives possibility to machine extremely large (up to ø2750 mm) shafts.

Influence of the Load-Bearing System of a High-Rise Building on its Stiffness

2015 ◽  
Vol 769 ◽  
pp. 29-35
Author(s):  
Olga Ivankova ◽  
Lenka Konecna
Keyword(s):  
Dynamic Analysis ◽  
Seismic Event ◽  
Short Description ◽  
Load Bearing ◽  
Static And Dynamic Analysis ◽  
High Rise ◽  
Wall System ◽  
Bearing System ◽  
Computing Models ◽  
Storey Building

Static and dynamic analysis of the high-rise (24-storey) building is discussed in this paper. The influence of the change of load-bearing system on its stiffness in the case of seismic event was detected. Two different load-bearing systems were chosen – the wall system (alt.1) and the skeleton system (alt.2). Finite element method was used for the solution of 3D computing models. Short description of the building, used material, applied load, a type of the subsoil and obtained results are mentioned. Dynamic analysis was repeated for four various seismic areas in Slovakia.

Fatigue Life Prediction of Microstructures

2012 ◽  
Author(s):  
Gustavo M. Castelluccio ◽  
David L. McDowell
Keyword(s):  
Grain Size ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Crack Formation ◽  
Fatigue Cracks ◽  
Fatigue Crack Initiation ◽  
Modeling Framework ◽  
Small Cracks ◽  
Engineering Alloys ◽  
Bimodal Grain Size

The formation and early growth of fatigue cracks in the high cycle fatigue regime is influenced by microstructuctural features such as grain size and morphological and crystallographic texture. However, most fatigue models do not predict the influence of the microstructure on early stages of crack formation, or they employ parameters that should be calibrated with experimental data from specimens with microstructures of interest. These post facto strategies are adequate to characterize materials, but they are not fully appropriate to aid in the design of fatigue-resistant engineering alloys. This paper presents a modeling framework that facilitates relative assessment of fatigue resistance among different microstructures. The scheme employs finite element simulations that explicitly render the microstructure and a methodology that estimates transgranular fatigue growth for microstructurally small cracks on a grain-by-grain basis, including consideration of growth within grains (embedded analytically) and stress redistribution as the cracks extend. The methodology is implemented using a crystal plasticity algorithm in ABAQUS and calibrated to study fatigue crack initiation of a bimodal grain size distribution found in RR1000 powder processed Ni-base superalloys for turbine disk applications.

The Structural Safety Test Research for 300 MW PWR Control Rod Driver Machine Pressured Shell

2005 ◽  
Author(s):  
Weiming Sun ◽  
Xing Ren ◽  
Kangda Zhang
Keyword(s):  
Safety Margin ◽  
Operating Mode ◽  
Structural Safety ◽  
Test Results ◽  
Load Bearing ◽  
Control Rod ◽  
Safety Test ◽  
Inner Pressure ◽  
Asme Code ◽  
Analyze Structure

The safety analysis and test research are done to inspect the safety of 300MW control rod drive machine (CRDM) pressured shell structure in a systematic way. The test result agrees accords with FEA result. In actual operating mode (300 °C) inner-pressure fatigue simulative test, the axial and hoop pre-cracks are made, and the fatigue crack growth is observed. The load-bearing capability and deformation are tested in shell-burst test. Based on test research, this paper analyses theoretical load-bearing capability and safety margin in accordance with ASME CODE Sec. III design is calculated. Elastic-plastic fracture mechanics theory and GEGB.R6 method is used to analyze structure safety. The test results show pressure shell’s safety allowance is large enough.

Parallel Load-Bearing and Damping System Design and Test for Satellite Vibration Suppression

2020 ◽  
Vol 10 (4) ◽  
pp. 1548 ◽  
Author(s):  
Shenyan Chen ◽  
Zihan Yang ◽  
Minxiao Ying ◽  
Yanwu Zheng ◽  
Yanjie Liu ◽  
...  
Keyword(s):  
Vibration Suppression ◽  
Fe Model ◽  
Damping Force ◽  
Load Bearing ◽  
Force Velocity ◽  
Design Requirements ◽  
Bearing Design ◽  
Series Type ◽  
Vibration Tests ◽  
Important Design

The traditional series-type satellite vibration suppression scheme significantly decreases satellite frequency, which leads to difficulty in controlling the amplitude. In the present work, a new parallel viscous damping scheme is adopted on the Payload Adaptor Fitting (PAF), which aims to integrate a load-bearing design and vibration reduction. The vibration amplitude and weight are the most important design requirements of the damping system. The Finite Element (FE) model of PAF was established. Through a series of analyses, the appropriate number and coefficient of dampers were determined. The damping force was calculated according to the damping coefficient and the relative velocity between the two ends of the damper. Based on the damping force and the installation dimensions, the damping rod was designed. The force–velocity test was carried out on the damping rod prototype, which showed its performance satisfies the requirements. With the topology optimization and sizing optimization technology, the light-weight supports were designed and manufactured. One damping rod and two supports were assembled as one set of dampers. Eight sets of dampers were installed on the PAF. Vibration tests were conducted on the damping state PAF. The results showed that the proposed system is effective at suppressing vibration and maintaining stiffness simultaneously.

New Standard for Assessment of Structural Integrity for Existing Load-Bearing Structures-Norsok N-006

2009 ◽  
Author(s):  
Gunnar Solland ◽  
Inge Lotsberg ◽  
Lars G. Bjo̸rheim ◽  
Gerhard Ersdal ◽  
Vidar-Andre´ Gjerstad ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Regulatory System ◽  
Life Extension ◽  
Design Standards ◽  
Load Bearing ◽  
Fatigue Design ◽  
Design Life ◽  
Advanced Analysis ◽  
The Cost ◽  
Existing Structure

An increasing number of platforms in the Norwegian continental shelf are reaching their design life. For various reasons these platforms will require an assessment of their structural integrity. When performing these assessments the engineer is faced with tasks where little guidance is found in design standards, for several reasons. The two most important being: 1) The analyses that is performed in a typical assessment of existing structure is often applying very advanced techniques and methodology that seldom is used in design of new structures, as the cost of doing advanced analysis is relatively low compared to replacement of an existing structure, but relatively high compared to moderate additions of e.g. steel in the design of a new structure. 2) Design standards are based on theories, methods and experience for structures in a given design life (e.g. fatigue design and corrosion protection design). When this design life is extended, sound methods for ensuring that the structures are still sufficient safe is needed. Such methods will normally be “condition based design”, where inspection, maintenance and repairs are included in the assessment in integrated way. Such methods are not given in normal design standards. For these reasons a new NORSOK standard is developed that gives recommendation on how to deal with the specific aspects that engineers meet when performing assessments of structures in general, but also specifically for assessment for life extension. The standard is named “Standard for Assessment of Structural Integrity for Existing Load-bearing Structures” and is issued as a NORSOK standard and given the number N-006 [1]. The topics that are covered in the standard include: Shut down and unmanning criteria for platforms not meeting ordinary requirements, specific issues for determination of ultimate capacities by use of non-linear methods, cyclic capacity checks, fatigue life extension, requirements to in-service inspection etc. The paper describes the background and the content of the new standard and it presents examples of recommendations given. The role of the new standard in the Norwegian regulatory system is shown.

scholarly journals Impact of local technological concentrators of stresses upon operation properties of parts worked

2017 ◽  
Vol 2 (5) ◽  
pp. 31-37
Author(s):  
Сергей Никитин ◽  
Sergey Nikitin ◽  
Владимир Макаров ◽  
Vladimir Makarov ◽  
Михаил Песин ◽  
...  
Keyword(s):  
Crack Formation ◽  
Fatigue Cracks ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Local Surface ◽  
Surface Machining ◽  
Gear Teeth ◽  
Conjugate Surfaces ◽  
Complex Profile Surfaces ◽  
Transition Areas

It is defined that during the machining of complex surfaces in parts operating under large fluctuating loads, in critical transition areas of profile conjugate surfaces there are formed local technological concentrators of stresses contributing to formation, development of fatigue cracks and to further destruction of parts in the course of operation. Such phenomena are discovered, for instance, at high-loaded gear teeth machining, at turbine blade profile surface machining, at manufacturing large-modular tapered threads and other parts having complex profile surfaces. There are developed and introduced methods for value decrease of such stress concentrators on the basis of the application of different methods for local surface plastic deformation of a surface layer in transition areas of profiles. As a result the probability of fatigue crack formation decreased considerably and fatigue strength in parts machined increased essentially.

scholarly journals BOUT THE PROBLEM OF ANALYSIS RESISTANCE BEARING SYSTEMS IN FAILURE OF A STRUCTURAL ELEMENT

2018 ◽  
Vol 14 (3) ◽  
pp. 103-113 ◽  
Author(s):  
Anatoly V. Perelmuter ◽  
Oleg V. Kabantsev
Keyword(s):  
Progressive Collapse ◽  
Universal Method ◽  
Dynamic Amplification Factor ◽  
Dynamic Calculation ◽  
Structural Element ◽  
Load Bearing ◽  
Static Calculation ◽  
Dynamic Amplification ◽  
Bearing Structure ◽  
Bearing System

This paper focuses on the methods of calculating load-bearing systems in the case of a failure of a structural element. This kind of failure makes it necessary to assess further behavior of the structure with a possibility of the progressive collapse development. The stress-strain state analysis of a load-bearing system in the case of a failure of a structure is carried out by two main methods – static and dynamic calculation. It is shown that the static calculation (quasi-static analysis using the dynamic amplification factor) is not a universal method. This paper justifies the application of the direct dynamic calculation in the mode of direct integration of motion for the design analysis of load-bearing systems with high rigidity stories (protection structures for a load-bearing system). It also gives recommendations for selecting parameters of the direct dynamic calculation in the case of a failure analysis of a bearing structure.

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