Infra-Red Thermography based Inspection of Hybrid Composite Laminates under Flexure Loading

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
R. Bhoominathan ◽  
P. Divyabarathi ◽  
R. Manimegalai ◽  
T. Nithya ◽  
S. Shanmugapriya
Keyword(s):  
Composite Laminates ◽  
Volume Fraction ◽  
Void Content ◽  
Destructive Testing ◽  
Flexural Loading ◽  
Infra Red ◽  
Before And After ◽  
Cfrp Composite ◽  
Structural Parts ◽  
Non Destructive

Generally, the aircraft structural parts are economically high in cost so the materials need to be inspected for defects or damages using various non-destructive testing (NDT) methods like ultrasonic, thermography and acoustic emission. The aim of this project is to characterize the defects in composite laminates before and after the flexural loading using infra-red thermography NDT method. GFRP and hybrid (GFRP+CFRP) composite laminates are fabricated with different orientation such as uni-directional, cross ply, anti-symmetric and angle ply and then tested under flexural loading according to ASTM D790 standard. The volume fraction of the fibre and matrix needs to be found out to know the void content and the mixing ratio of reinforcement and binder.

scholarly journals Assessment of Timber Roof Structures before and after Earthquakes

Buildings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 528
Author(s):  
Nikola Perković ◽  
Mislav Stepinac ◽  
Vlatka Rajčić ◽  
Jure Barbalić
Keyword(s):  
Test Methods ◽  
Timber Structures ◽  
Destructive Testing ◽  
Policy Makers ◽  
Load Bearing ◽  
Existing Structures ◽  
Roof Structure ◽  
Before And After ◽  
Timber Roof Structures ◽  
Non Destructive

The global objective of sustainable development has been greatly directed toward the preservation of existing structures. Therefore, condition assessment and reconstruction of existing timber structures have been gaining importance in recent times. This is particularly evident on timber roofs whose elements are exposed to degradation, either because of rheological effects or due to the direct influence of moisture and biological factors. In case of accidental events, such as an earthquake, the question of the structure’s condition is essential for the condition of the entire building. In order to prove the load-bearing capacity and serviceability of existing structures, as well as to check the need for reconstruction, it is necessary to define crucial parameters that are influencing the condition of materials, elements, and systems. Although there are many non destructive testing methods, the frequency and scope of their use, as well as the decision-making approach, have not been defined. In the paper, non-destructive and semi-destructive methods frequently used for timber structures are explained. A systematic review of criteria to be used in the assessment of load-bearing timber structures in a seismic active area was the main objective of this paper as well as the illustration of non-destructive and semi-destructive test methods through a case study involving roof construction of a hundred-year-old building in Zagreb, Croatia. Pre- and post-earthquake inspection was made. The overall condition of the roof structure after two significant earthquakes can be assessed as satisfactory given that the observed system is a large-span and massive roof structure. The presented results and identification of typical damages after the earthquake are presented in order to facilitate policy makers and for the future implementation of development strategies in the renovation of the city.

Pressurized Infusion: A New and Improved Liquid Composite Molding Process

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
M. Akif Yalcinkaya ◽  
Gorkem E. Guloglu ◽  
Maya Pishvar ◽  
Mehrad Amirkhosravi ◽  
E. Murat Sozer ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Composite Laminates ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Compaction Pressure ◽  
External Pressure ◽  
Void Content ◽  
Liquid Composite Molding ◽  
Molding Process ◽  
Fiber Volume

Vacuum-assisted resin transfer molding (VARTM) has several inherent shortcomings such as long mold filling times, low fiber volume fraction, and high void content in fabricated laminates. These problems in VARTM mainly arise from the limited compaction of the laminate and low resin pressure. Pressurized infusion (PI) molding introduced in this paper overcomes these disadvantages by (i) applying high compaction pressure on the laminate by an external pressure chamber placed on the mold and (ii) increasing the resin pressure by pressurizing the inlet resin reservoir. The effectiveness of PI molding was verified by fabricating composite laminates at various levels of chamber and inlet pressures and investigating the effect of these parameters on the fill time, fiber volume fraction, and void content. Furthermore, spatial distribution of voids was characterized by employing a unique method, which uses a flatbed scanner to capture the high-resolution planar scan of the fabricated laminates. The results revealed that PI molding reduced fill time by 45%, increased fiber volume fraction by 16%, reduced void content by 98%, improved short beam shear (SBS) strength by 14%, and yielded uniform spatial distribution of voids compared to those obtained by conventional VARTM.

scholarly journals Extended Non-destructive Testing Technique Demonstration in a Realistic Environment with Technology Assessment

2021 ◽  
pp. 259-330
Author(s):  
Romain Ecault ◽  
Ana Reguero Simon ◽  
Célian Cherrier ◽  
Paweł H. Malinowski ◽  
Tomasz Wandowski ◽  
...  
Keyword(s):  
Technology Assessment ◽  
Full Scale ◽  
Probability Of Detection ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Evaluation Procedures ◽  
Structural Parts ◽  
First Time ◽  
Non Destructive ◽  
Testing And Evaluation

AbstractThis chapter highlights two advances towards a higher maturity of versatile extended non-destructive testing (ENDT) procedures. Full-scale demonstration tests are presented in realistic user application cases that involve typical production or repair scenarios. Subsequently, the investigations used to assess the probability of detection (POD) are detailed for the respective ENDT processes and application-relevant scenarios in a realistic environment. Although some results indicated that some additional in-depth investigations would be even more enlightening, these demonstrations still clearly showed that developments and progress described in the previous chapters have enabled some of the technologies to achieve a maturity that is sufficient to proceed towards industrial implementation. Some ENDT techniques revealed the presence of contaminants on real structural parts with unknown contaminant amounts. For the first time, POD results obtained for ENDT investigations are presented. Some ENDT procedures permitted POD results to be obtained for several scenarios, while others showed technologically relevant POD only for certain scenarios. For two ENDT techniques, determining the POD helped to enhance the respective testing and evaluation procedures. In most of the cases, it was possible to estimate a preliminary quantification of POD by giving the POD90/95. For some techniques, this value was below the lowest contamination degree.

scholarly journals Integrating Extended Non-destructive Testing in the Life Cycle Management of Bonded Products—Some Perspectives

2021 ◽  
pp. 331-350
Author(s):  
Welchy Leite Cavalcanti ◽  
Elli Moutsompegka ◽  
Konstantinos Tserpes ◽  
Paweł H. Malinowski ◽  
Wiesław M. Ostachowicz ◽  
...  
Keyword(s):  
Life Cycle ◽  
Sensor Arrays ◽  
Product Management ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Related Data ◽  
Related Information ◽  
Post Process ◽  
Structural Parts ◽  
Non Destructive

AbstractIn this chapter, we outline some perspectives on embracing the datasets gathered using Extended Non-destructive Testing (ENDT) during manufacturing or repair process steps within the life cycle of bonded products. Ensuring that the ENDT data and metadata are FAIR, i.e. findable, accessible, interoperable and re-usable, will support the relevant stakeholders in exploiting the contained material-related information far beyond a stop/go decision, while a shorter time-to-information will facilitate a prompter time-to-decision in process and product management. Exploiting the value of ENDT (meta)data will contribute to increased performance by integrating all defined, measured, analyzed and controlled aspects of material transformation across process and company boundaries. This will facilitate the optimization of manufacturing and repair operations, boosting their energy efficiency and productivity. In this regard, some aspects that are currently driving activities in the field of pre-process, in-process and post-process quality assessment will be addressed in the following. Furthermore, some requirements will be contemplated for harmonized and conjoint data transfer ranging from a bonded product’s beginning-of-life through its end-of-life, the customization of stand-alone or linked ENDT tools, and the implementation of sensor arrays and networks in joints, devices and structural parts to gather material-related data during a product’s middle-of-life application phase, thereby fostering structural health monitoring (SHM).

Void reduction in VARTM composites by compaction of dry fiber preforms with stationary and moving magnets

2018 ◽  
Vol 53 (6) ◽  
pp. 769-782 ◽  
Author(s):  
Mehrad Amirkhosravi ◽  
Maya Pishvar ◽  
M Cengiz Altan
Keyword(s):  
Composite Laminates ◽  
Volume Fraction ◽  
Compaction Pressure ◽  
Void Content ◽  
Novel Method ◽  
Improved Performance ◽  
Small Parts ◽  
Induced Defects ◽  
Fiber Preforms

Voids are the most common process-induced defects in composite laminates fabricated by vacuum assisted resin transfer molding (VARTM). Reduction or total elimination of these defects is essential for the improved performance and long-term durability of the structural composites. This study introduces a novel method that reduces the void content in VARTM laminates to below 1% by compacting the fibrous mat before infusion. The compaction is achieved by applying magnetic pressure on the vacuum bag by either stationary or moving magnets which are removed before the resin infusion. To assess the effectiveness of the proposed method, 6-, 12-, and 18-ply random mat glass/epoxy laminates are fabricated by VARTM using compacted and uncompacted mats and their properties are compared. In addition, different sets of magnets are used to investigate the effect of compaction levels on the resin flow and the quality of the final part. The placement of stationary magnets on the entire vacuum bag surface is practical for fabrication of small parts. For medium to large parts, however, magnets with a smaller footprint can be moved to apply the compaction pressure over a larger vacuum bag surface. The results show that by applying compaction pressure of 0.2 MPa or higher either by stationary or moving magnets on the dry preforms, the void volume fraction was decreased by 65%–95% to 0.1%–0.8% in all laminates.

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