Determination of the Fatigue Behavior of Aluminide Coatings by Means of the Impact Testing Method

2007 ◽  
Vol 348-349 ◽  
pp. 645-648
Author(s):  
Kostas David ◽  
K.G. Anthymidis ◽  
P. Agrianidis ◽  
D.N. Tsipas
Keyword(s):  
Fatigue Failure ◽  
Fatigue Resistance ◽  
Failure Modes ◽  
Impact Load ◽  
Fatigue Behavior ◽  
Impact Testing ◽  
Testing Method ◽  
Aluminide Coatings ◽  
The Impact

The impact testing is an efficient experimental method that enables the quantitative and qualitative determination of the fatigue resistance of mono- and multilayer coatings deposited on various substrates, which was not possible with the common testing methods previously available. In this paper the experimental assessment of the fatigue resistance of coatings working under cyclic loading conditions by means of the dynamic impact testing method is presented. The fatigue failure mode, such cohesive or adhesive, of the investigated coatings is determined using scanning electron and optical microscopy, as well as EDX analysis. Critical values of the stress components, responsible for distinctive fatigue failure modes of the coating substrate system are obtained and the fatigue limits of aluminide coatings are illustrated in simple diagrams containing the impact load versus the number of successive impacts that the examined aluminide-P91 system can withstand.

Influence of Human Error on Structural Reliability

2017 ◽  
Author(s):  
Eric Brehm ◽  
Robert Hertle ◽  
Markus Wetzel
Keyword(s):  
Human Error ◽  
Structural Reliability ◽  
Failure Modes ◽  
Structural Model ◽  
Limit State ◽  
Design Procedure ◽  
Material Strength ◽  
Limit States ◽  
The Impact

In common structural design, random variables, such as material strength or loads, are represented by fixed numbers defined in design codes. This is also referred to as deterministic design. Addressing the random character of these variables directly, the probabilistic design procedure allows the determination of the probability of exceeding a defined limit state. This probability is referred to as failure probability. From there, the structural reliability, representing the survival probability, can be determined. Structural reliability thus is a property of a structure or structural member, depending on the relevant limit states, failure modes and basic variables. This is the basis for the determination of partial safety factors which are, for sake of a simpler design, applied within deterministic design procedures. In addition to the basic variables in terms of material and loads, further basic variables representing the structural model have to be considered. These depend strongly on the experience of the design engineer and the level of detailing of the model. However, in the clear majority of cases [1] failure does not occur due to unexpectedly high or low values of loads or material strength. The most common reasons for failure are human errors in design and execution. This paper will provide practical examples of original designs affected by human error and will assess the impact on structural reliability.

Study on the effect of length–short side ratio on the fatigue performance of the rib girder bridge's carriageway slab

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tianlai Yu ◽  
Linlin Zhang ◽  
Zizheng Liu
Keyword(s):  
Reinforced Concrete ◽  
Fatigue Failure ◽  
Fatigue Resistance ◽  
Failure Modes ◽  
Group Structure ◽  
Load Level ◽  
Fatigue Performance ◽  
Short Side ◽  
Content Type ◽  
Side Ratio

PurposeThe fatigue problems of the carriageway slabs of reinforced concrete rib-beam bridges were studied. The analysis of the carriageway slabs could not achieve the actual stress state.Design/methodology/approachBased on this characteristic, the reinforced concrete T-beam group structure system was taken as the research object. Four scale models of the carriageway slabs of reinforced concrete ribbed bridges were designed. The fatigue failure modes and actual fatigue resistance of the carriageway slabs with different length-to-side ratios were systematically studied through static load and fatigue experiments. Based on this, the concrete damage plasticity model (CDP model) was combined with numerical simulation analysis to study the influence of the length-to-short-side ratio of the carriageway slab on the fatigue performance and the remaining bearing capacity.FindingsThe results show that the fatigue failure of the carriageway slab is a three-stage failure; the ratio of the long and short sides has a significant effect on the fatigue performance of the carriageway slab. Under the same fatigue load level, the smaller the ratio of the long and short sides of the carriageway slab.Originality/valueThe fatigue resistance of the unidirectional board is significantly lower than that of the bidirectional board. It is recommended to use the bidirectional board in actual engineering design.

scholarly journals Investigation on the Application of Taylor Impact Test to High-G Loading

2021 ◽  
Vol 8 ◽  
Author(s):  
Li Juncheng ◽  
Chen Gang ◽  
Lu Yonggang ◽  
Huang Fenglei
Keyword(s):  
Pulse Duration ◽  
Impact Loading ◽  
Impact Test ◽  
Impact Load ◽  
Low Cost ◽  
Large Mass ◽  
Impact Testing ◽  
Taylor Impact ◽  
Taylor Impact Test ◽  
The Impact

Taylor impact test is characterized by high impact energy, low cost, and good repeatability, giving it the technical foundation and development potential for application in high-g loading. In this paper, the feasibility of performing high-g load impact testing to a missile-borne recorder by conducting Taylor impact test was studied by combining simulation analyses with experimental verification. Acccording to the actual dimensions of the missile-borne recorder, an experimental piece was designed based on the Taylor impact principle. The impact loading characteristics of the missile-borne recorder were then simulated and analyzed at different impact velocities. In addition, the peak acceleration function and the pulse duration function of the load were fitted to guide the experimental design. A Taylor-Hopkinson impact experiment was also conducted to measure the impact load that was actually experienced by the missile-borne recorder and the results were compared with the results of strain measurements on the Hopkinson incident bar. The results showed that the peak value of impact load, the pulse duration and the waveform of the actual experimental results were in good agreement with the results predicted by the simulations. Additionally, the strain data measured on the incident bar could be used to verify or replace the acceleration testing of the specimen to simplify the experimental process required. Based on the impact velocity, high-g loading impact was achieved with peak values in the 7,000–30,000 g range and durations of 1.3–1 ms, and the waveform generated was a sawtooth wave. The research results provide a new approach for high amplitude and long pulse duration impact loading to large-mass components, and broaden the application field of Taylor impact test.

scholarly journals DYNAMIC IMPACT WEAR AND IMPACT RESISTANCE OF W-B-C COATINGS

2020 ◽  
Vol 27 ◽  
pp. 37-41
Author(s):  
Josef Daniel ◽  
Jan Grossman ◽  
Vilma Buršíková ◽  
Lukáš Zábranský ◽  
Pavel Souček ◽  
...  
Keyword(s):  
Impact Test ◽  
Impact Load ◽  
Protective Coatings ◽  
Impact Resistance ◽  
Impact Testing ◽  
The Novel ◽  
Test Results ◽  
Dynamic Impact ◽  
Impact Deformation ◽  
The Impact

Coated components used in industry are often exposed to repetitive dynamic impact load. The dynamic impact test is a suitable method for the study of thin protective coatings under such conditions. Aim of this paper is to describe the method of dynamic impact testing and the novel concepts of evaluation of the impact test results, such as the impact resistance and the impact deformation rate. All of the presented results were obtained by testing two W-B-C coatings with different C/W ratio. Different impact test results are discussed with respect to the coatings microstructure, the chemical and phase composition, and the mechanical properties. It is shown that coating adhesion to the HSS substrate played a crucial role in the coatings’ impact lifetime.

Determination of the Fatigue Resistance of HVOF Thermal Spray WC-CoCr Coatings by Means of Impact Testing

2007 ◽  
Vol 35 (6) ◽  
pp. 100922 ◽  
Author(s):  
M. R. Mitchell ◽  
R. E. Link ◽  
Constantine David ◽  
Konstantinos Anthymidis ◽  
Pavlos Agrianidis ◽  
...  
Keyword(s):  
Thermal Spray ◽  
Fatigue Resistance ◽  
Impact Testing ◽  
Hvof Thermal Spray

Impact Damage Monitoring in Composite Plates

2004 ◽  
Author(s):  
Frank J. Shih ◽  
Sauvik Banerjee ◽  
Ajit K. Mal
Keyword(s):  
Impact Load ◽  
Impact Damage ◽  
Composite Plates ◽  
Impact Testing ◽  
Far Field ◽  
Internal Damage ◽  
Distributed Sensors ◽  
Surface Motion ◽  
Impact Monitoring ◽  
The Impact

This paper is concerned with the real-time detection of internal damage in composite structural components during impact using the far-field surface motion generated by these events. Impact tests are carried out on graphite epoxy composite plates using an instrumented impact testing system. Contact force and surface motion are measured at several locations on the plate surface. The far-field surface motions, both flexural and extensional waves in the composite plate, are modeled using both approximate and exact solution methods. Postimpact test were performed to determine the extent of internal damage caused by the impact load. Further research on the detection method can lead to the development of a viable impact monitoring system for composite aerospace structures using distributed sensors.

Study on damage behavior of carbide tool for milling difficult-to-machine material

2018 ◽  
Vol 233 (2) ◽  
pp. 735-747
Author(s):  
Yao-Nan Cheng ◽  
Wan-Ying Nie ◽  
Rui Guan ◽  
Wei-Kun Jia ◽  
Fu-gang Yan
Keyword(s):  
Failure Modes ◽  
Impact Load ◽  
Impact Damage ◽  
High Plasticity ◽  
Carbide Tool ◽  
Machine Material ◽  
Tool Failure ◽  
Damage Behavior ◽  
Tool Damage ◽  
The Impact

Water chamber head is an important component of nuclear power unit, and the main material is 508 III steel of difficult-to-machine material, which has the characteristics of high hardness, high strength, high plasticity and high profile shrinkage, etc. During the milling process, the tool is subjected to the cyclic impact load, which make cutting force and cutting heat change violent and occurrence of tool damage failure accelerate. In this paper, the damage behavior of carbide tool for milling difficult-to-machine material is studied first, and then field experiment was carried out on 508 III steel material, tool failure modes were analyzed, which include impact damage and fatigue fracture, and the failure theory and the crack propagation of carbide material were investigated in the process of tool damage. Then, the impact damage model of carbide tool is established based on the classical strength theory, and the critical condition of impact damage is determined according to simulation analysis. Finally, the theoretical model of carbide tool fatigue life is established and the tool fatigue limit is analyzed. Theoretical basis and technical support are provided for the tool failure mechanisms analysis, life prediction, parameter optimization, tool design and development aspects during the study.

Evaluation of the Fatigue Resistance of Chromium Slurry Coating Steel Substrate Compounds by Means of an Improved Impact Testing Procedure

2011 ◽  
Vol 488-489 ◽  
pp. 420-423
Author(s):  
K.G. Anthymidis ◽  
Kostas David ◽  
A. Trakali ◽  
D.N. Tsipas
Keyword(s):  
Fatigue Resistance ◽  
Power Plants ◽  
Steel Substrate ◽  
Turbine Blades ◽  
Testing Procedure ◽  
Impact Testing ◽  
Experimental Results ◽  
Limited Information ◽  
Cyclic Impact ◽  
The Impact

Chromium coatings have been used for the protection of gas turbine blades in power plants during the last years due to their very good resistance against steam corrosion. Microhardness, scratch, adhesion and pin-on-disk sliding tests are commonly used for rapid evaluation of the mechanical properties of these coatings [1,2]. However, very limited information exists on their fatigue resistance. In this paper we present the experimental results of the impact testing examination of the above coatings. This experimental method is capable to assess the fatigue and the impact wear resistance of coatings working under cyclic impact loading conditions. From the experimental results it was concluded that the slurry Cr, Zr coatings deposited on P91 steel showed adequate fatigue strength for the above-mentioned kind of use.

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