Delamination During Drilling in Composite Laminates

1990 ◽  
Vol 112 (3) ◽  
pp. 236-239 ◽  
Author(s):  
H. Ho-Cheng ◽  
C. K. H. Dharan
Keyword(s):  
Composite Laminates ◽  
Structural Integrity ◽  
Force Feedback ◽  
Thrust Force ◽  
Hybrid Composites ◽  
Assembly Tolerance ◽  
Delamination Fracture ◽  
Performance Deterioration ◽  
Long Term Performance ◽  
Term Performance

Delamination is the major concern during drilling of composite laminates. Delamination, in addition to reducing the structural integrity of the laminate, also results in poor assembly tolerance and has the potential for long-term performance deterioration. Drilling-induced delamination occurs both at the entrance and at the exit planes. This paper presents an analysis of delamination during drilling. The analysis uses a fracture mechanics approach in which the opening-mode delamination fracture toughness, a material parameter, is used with a plate model of the laminate. The analysis predicts an optimal thrust force (defined as the minimum force above which delamination is initiated) as a function of drilled hole depth. Good agreement is achieved with data obtained from drilling carbon fiber-epoxy laminates. An advantage of the model is that it can predict varying degrees of delamination for other materials, such as glass fiber-epoxy, and for hybrid composites. In addition, the optimal thrust force for no delamination can be used to control a drilling machine with thrust force feedback for maximizing productivity.

Long-term performance deterioration models for semi-rigid asphalt pavement in cold region

2021 ◽  
Vol 14 (6) ◽  
pp. 697-707 ◽  
Author(s):  
Ling Yu ◽  
Lingyun You ◽  
Huaizhi Zhang ◽  
Siyu Jia ◽  
Yitong Zhang ◽  
...  
Keyword(s):  
Asphalt Pavement ◽  
Cold Region ◽  
Performance Deterioration ◽  
Long Term Performance ◽  
Term Performance

scholarly journals Data Analytics for Performance Monitoring of Gas Turbine Engine

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
Yuan Liu ◽  
Avisekh Banerjee ◽  
Thambirajah Ravichandran ◽  
Amar Kumar ◽  
Glenn Heppler
Keyword(s):  
Gas Turbine ◽  
Performance Monitoring ◽  
Gas Turbine Engine ◽  
Short Term ◽  
Turbine Engine ◽  
Free Data ◽  
Performance Deterioration ◽  
Long Term Performance ◽  
Term Performance

Performance analysis of a low power rating and partially loaded industrial gas turbine engine (GTE) was carried out by using a model-free data analytic approach. By adopting an efficient input selection method, several performance indices (PI) are proposed to quantify the performance of the GTE. These indices are extracted using engine operating data related to power output and parameters related to fuel consumption, and validated with engine performance monitoring measurements for a three year period corresponding to one time between overhaul intervals. The dependency of the PIs on ambient temperature has been studied by using linear and polynomial fitting curves. Then novel methods are introduced for analysis of short-term and long-term performance deterioration arising from compressor fouling and structural degradation respectively. The results have clearly shown the ability of the proposed PIs to detect short-term compressor fouling as well as long-term performance deterioration, which is directly relevant to the Prognostics and Health Management of gas turbine engine.

scholarly journals Strength Behavior of Lateritic Soil Treated with Alccofine

2019 ◽  
Vol 9 (1) ◽  
pp. 1995-1999
Keyword(s):  
Shear Strength ◽  
Structural Integrity ◽  
Soil Stabilization ◽  
Engineering Properties ◽  
Lateritic Soil ◽  
Weak Soil ◽  
The Stability ◽  
Long Term Performance ◽  
Term Performance

One of the factors that affect the long term performance of a structure is the strength of the underlying soil strata. Presence of weak soil strata beneath the structure will affect the structural integrity. So, enhancing the engineering properties of the weak soil results in the betterment of bearing capacity of the soil. Nowadays, for improving the stability of the weak soil, various soil stabilization techniques are adopted. This paper presents an investigation of using alccofine as a soil stabilizing agent. Variation in shear strength parameters and compaction parameters of the soil is studied by adding different percentages of alccofine 1101 such as 1%, 2%, 3%, 4%, and 5%. Test results revealed that at the optimal rate of alccofine 1101, the shear strength characteristic is increased by 53.71% after a curing period of 3 days.

Material state changes as a basis for prognosis in aeronautical structures

2009 ◽  
Vol 113 (1150) ◽  
pp. 789-798 ◽  
Author(s):  
K. L. Reifsnider ◽  
P. Fazzino ◽  
P. K. Majumdar ◽  
L. Xing
Keyword(s):  
High Performance ◽  
Structural Integrity ◽  
Future Performance ◽  
Material State ◽  
History Of ◽  
Small Set ◽  
History Of Use ◽  
Long Term Performance ◽  
Term Performance

Abstract The long-term performance of aeronautical structures is typically discussed in terms of concepts such as structural integrity, durability, damage tolerance, fracture toughness, etc. These familiar concepts are usually addressed by considering balance equations, crack growth relationships, and constitutive equations with constant material properties, and constant or cyclically applied load conditions. Loading histories are represented by changing stress (or strain) states, only. But for many situations, especially associated with high performance aircraft, the local state of the material may also change during service, so that the properties used in those equations are functions of time and history of applied conditions. For example, local values of stiffness, strength, and conductivity are altered by material degradation to create ‘property fields’ that replace the global constants, and introduce time and history into the governing equations. The present paper will examine a small set of such problems and offer a construct for using related solutions to estimate future performance based on history of use and current material state, a concept typically called prognosis.

scholarly journals Leachability and Microstructural Analysis of Clay and Lime Stabilized/Solidified Polluted Sediment – Long-Term Performance

2019 ◽  
Vol 64 (1) ◽  
pp. 93-105 ◽  
Author(s):  
Djurdja Kerkez ◽  
Dunja Radjenović ◽  
Dragana Tomašević Pilipović ◽  
Milena Bečelić-Tomin ◽  
Nataša Slijepčević ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Microstructural Analysis ◽  
Product Formation ◽  
Sem Analysis ◽  
Polluted Sediment ◽  
German Standard ◽  
Long Term Performance ◽  
Term Performance ◽  
Over Time

The objective of this study is to enable a better understanding of the effectiveness of solidification/stabilization (S/S) technique in treating polluted sediment, and provide the much needed validation of the longevity of the technology. In this research kaolinite and montmorillonite, with a certain proportion of lime, were used for S/S treatment of sediment polluted with metals. Leachability of metals was examined using the toxicity characteristic leaching procedure (TCLP) and the German standard leaching test (DIN 3841-4 S4) prescribed in national legislative. Results indicated successful S/S treatment using both clays and lime, from the aspect of all leached metals even with pH variations over time and slight changes in structural integrity of specimens. X-ray diffraction (XRD), scanning electron microscope (SEM) analyses and porosity measurement were also performed on the prepared monolithic matrices. XRD qualitative and semi-quantitative analysis proved hydration and pozzolanic product formation with increase in their content and finer crystallites formation over time. SEM analysis confirmed the presence of morphologically dense and stable structures while pore size distribution indicated on mesoporous matrices with ongoing compaction over time. Generally, structural microanalysis indicated the formation of hardened matrices over time and hydration process has been fully completed and further carbonation took place. Unconfined compressive strength measurement gave the satisfying results and matured monolite with 30 % of montmorillonite and 10 % of lime can be considered potentially applicable as non-load-bearing material. In summary, all results indicated that this kind of S/S treatment can achieve satisfactory durability and represent reliable and economically feasible technique for long-term remediation of metal polluted sediment.

Fine Particle Mass Monitoring with Low-Cost Sensors: Corrections and Long-Term Performance Evaluation

2019 ◽  
Author(s):  
Carl Malings ◽  
Rebecca Tanzer ◽  
Aliaksei Hauryliuk ◽  
Provat K. Saha ◽  
Allen L. Robinson ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Fine Particle ◽  
Low Cost ◽  
Particle Mass ◽  
Long Term Performance ◽  
Term Performance

Long-term performance of the Hancock bioprosthetic conduit for aortic root replacement

2008 ◽  
Vol 56 (S 1) ◽  
Author(s):  
CC Badiu ◽  
W Eichinger ◽  
D Ruzicka ◽  
I Hettich ◽  
S Bleiziffer ◽  
...  
Keyword(s):  
Aortic Root ◽  
Aortic Root Replacement ◽  
Long Term Performance ◽  
Term Performance
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