Condition Structural Index using Principal Component Analysis for undamaged, damage and repair conditions of carbon fiber-reinforced plastic laminate

This article deals with the data reduction technique using the principal component analysis applied to the carbon fiber–reinforced plastic panels for structural health monitoring approaches. Two carbon fiber–reinforced plastic panels subjected to damage and repair coincide with typical aircraft repair procedures found in the aircraft structural repair manual. The panels were simulated with 30 mm diameter of partial and full penetration damages using a diamond-coated router. The data (50 observations) were captured for the undamaged, damaged, and repaired conditions by placing lead zirconate titanate smart sensors at 100 mm across the damaged and repaired structures. A time-based data response was captured for post analysis during the interrogation on the structure at each condition. The raw data were captured in a Lamb waveform, and the interested features were extracted using Morlet wavelet analysis to evaluate the Condition Structural Index and Amplitude-Based Assessment for each condition retrieved from the Gaussian-like distribution. The results were evaluated using the principal component analysis technique in order to distinguish the characteristic of the undamaged, damaged, and repaired conditions. The results showed that in all cases considered, it was possible to distinguish the conditions of undamaged, damaged, and repaired states with promising accuracy and repeatability of the data

A structural health monitoring of a pitch catch active sensing of PZT sensor on normal, damage and repair aircraft spoiler

At present, aircraft structural integrity is a concerned due to heavy usage of composite materials and cost saving on the operational. Structural health monitoring system is one of condition based monitoring introduced to supplement the current aircraft maintenance non destructive inspection. One approach is to embed or attach sensors such as lead zirconate titanate (PZT) to detect the anomalies either passively or actively. Due to the aircraft operational environment the defects and damage are likely to occur. Repair has to be carried out as per recommended and the requirement to replace back the sensors are important in order to monitor back the structure at post repair situation. The Lamb waves generated by using the PZT sensor can be used to monitor the surface structural integrity for damage or pristine condition. The effect of the lamb wave signals when surface condition of the aircraft component changes is concerned. One hundred data sets were recorded for the undamaged, damage and repair condition. An outlier analysis was used to analyze the situation by overlaying the isolated signal spectrum and the range of the voltage peak to peak (Vpp) mean values. Different signals were observed for different type of structural condition tested and more tests were required to make a conclusive solution

Fabrication technique for bio-composite patch repair on laminated structures of CFRP plate

Laminated structures are assembled so that the fibre orientation provides most of desired mechanical properties and the matrix largely determines the environmental performance. Composites laminate structures are used in a wide range of applications in aerospace, marine, automotive, surface transport and sports equipment markets. Damage to composite components is not always visible to the naked eye and the extent of damage is best determined for structural components by suitable Non Destructive Test (NDT) methods. Alternatively the damaged areas can be located by simply tapping the composite surface and listening to the sound. The damaged areas give a dull response to the tapping, and the boundary between the good and damaged composite can easily be mapped to identify the area for repair. Awareness of and inspection for composite damage should be included in the regular maintenance schedules for composite structures. Particular attention would be made to areas which are more prone to damage. The repair can be done by using composite itself or bio-composite. Bio-composite is a reinforcement of natural fibre such as plant and a material that formed by matrix or resin. Then repairs to aircraft structures are controlled and should be carried out according to the Aircraft Structural Repair Manual (SRM). For other applications the repaired components would normally be expected to meet the original specifications and mechanical performance requirements. This paper presents the fabrication technique including patch repair by using bio-composite which is kenaf and its aim to give a general approach to composite fabrication on patch repair in all applications. Through the described approach, the life of the structure is expanded and met the properties requirements such as low cost, fairly good mechanical properties, high specific strength, non-abrasive, eco-friendly and bio-degradability characteristics

A Structural Health Monitoring (SHM) of composite patch repair for aircraft part and structures using principal component analysis

The use of advanced composite structures on aircraft is increasing. New aircraft, such as the Airbus A350 and the Boeing B787, have more than 50% of their structure originating from composite materials especially carbon fiber reinforced plastic (CFRP). Delamination, disbonding, voids and barely visible internal damage (BVID) are some of the damages uniquely found in the composite structure. Once the repair is carried out, the structural health monitoring (SHM) has the ability to detect structural anomalies where human dependency can be minimized. However, most SHM works are concentrating on pristine structure on repaired structure. Therefore the behaviour of SHM at undamaged, damaged and repaired conditions on carbon fiber reinforced plastic (CFRP) are being investigated in this research.. The motivation of the research is to optimize the structural health monitoring (SHM) in comparing the structural response undamaged, damaged and repaired of CFRP structures by using Principal Component Analysis (PCA) through Amplitude Based Assessment (ABA) and Conditional Structural Index (CSI). The objectives of the research are to undertake a feasibility study on Lamb wave propagation over undamaged, damaged and repaired composite panels via smart PZT sensor by using PCA to evaluate the structural conditions of CFRP panels. PZT sensors are used to interrogate and retrieve the surface wave across the investigated structures via online and offline on the undamaged damaged and repaired structures of similar origin. Result shows that although the structural integrity has returned back to its pristine condition, the repaired structure response is diverging from the undamaged conditions. The novelty in this research is the comparative results between undamaged, damaged and repaired response of an aircraft structures originated from CFRP panels which will assist in interpreting the structural health status at maintenance level

A condition structural index (CSI) using principal component analysis (PCA) for normal, damage and repair conditions of CFRP laminate

The paper deals with data reduction technique by using the principle component analysis (PCA) applied to the carbon fiber reinforced plastic (CFRP) panels for structural health monitoring study. Two CFRP panels were subjected to damage and repair coincide with typical aircraft structural repair manual (SRM). Data was taken at normal/ undamaged, damaged and repaired condition by placing PZT smart sensors at predetermined distanced across the damaged and repaired structure. A time-based data response was captured for post analysis during the interrogation on the structure at each condition. The raw data was captured in a Lamb wave form and only the interested intervals were selected by using Morlet wavelet analysis to evaluate the Condition Structural Index (CI) and Amplitude Based Assessment (ABA) for each conditions. The results were evaluated by using the PCA technique in order to distinguish the characteristic of the normal, damage and repair conditions. The results showed that in all cases considered, it was possible to distinguish the conditions of normal, damaged and repaired states with promising accuracy and repeatability of the data