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Technical Paper

Fatigue Endurance Limit of Fasteners in Automotive Application

2022-03-29
2022-01-0260
Fastener commonly used in automotive industry plays an important role in the safety and reliability of the vehicle structural systems. In practical application, bolted joint would never undergo fully reversed loading, there always will be positive mean stress on bolt. The mean stress has little influence on the fatigue life if the maximum stress is lower than a threshold, which is the yield stress of the bolt. However, when the sum of the mean stress and the stress amplitude exceeds the yield stress, the endurance limit stress amplitude decreases fast as the mean stress increases. The purpose of this paper is to research fatigue endurance limit of fastener and establish the threshold for safe design in automotive application. In order to obtain the fatigue endurance limit at different mean stress levels, various mechanical tests were performed on M12x1.75 and M16x1.5 Class 10.9 fasteners using MTS test systems.
Technical Paper

An On-line path correction method based on 2D laser profile measurement for Gluing Robot

2022-03-08
2022-01-0016
Gluing is an essential fastening step in the field of aircraft assembly except for riveting and bolting. Generally, the robotic programs of gluing are generated in CAM environment. Due to the positioning errors and deformation of the workpiece to be glued in the fixture, the nominal pose and the actual pose of the workpiece are no longer consistent with each other. The Robot trajectory of dispensing glue are adjusted manually according to the actual pose of the workpiece by robot teaching. In this paper, an on-line gluing path correction method is developed by 2D laser profile measurement. A pose calibration method for 2D laser profiler integrated into a gluing robot by measuring a fixed center point of a standard ball is proposed to identify the position and orientation of the laser sensor, which enables the accurate transforming coordinates between the robot frame and the sensor frame. Meanwhile, the pose of the gluing tool mounted on the end of the robot is calibrated.
Technical Paper

Intuitive Robot Programming and Path Planning based on Human-Machine Interaction and Sensory Data for Realization of various Aircraft Application Scenarios

2022-03-08
2022-01-0011
Human-machine interaction (HMI) technologies enable the automation of various manufacturing and assembly applications while maintaining high flexibility. In this context, human-robot collaboration (HRC) capable robots should no longer function as autonomous systems, but much more as assistance systems or as colleagues for workers. In connection with shorter product life cycles, increasing variant diversity and individualization, the challenge arises to set up flexible robot systems, which can be reprogrammed and commissioned with little effort in a short period of time with preservation of the required accuracies. Therefore intelligent path planning is essential for development of flexible robot systems. In this paper different approaches are presented that allow the worker on the shop floor to rapidly and easily program a robot to implement new motion tasks based on a camera system without programming knowledge. Thereby various points are selected manually on an image.
Technical Paper

Simulation Environment for Modeling and Testing of Autonomous Assembly in Space for Multiple Robotic Arms

2022-03-08
2022-01-0012
Multi-arm robotic assembly in space is an increasingly popular research topic as robotic arms can be used to decrease repair costs. We propose a simulation framework to model different scenarios of multi-arm robotic assembly in space with an ever-changing harsh environment. Simulation is a valuable, viable, and low-cost option for testing the developed algorithms without the need to re-create the orbital conditions in an elaborate and expensive laboratory environment. The proposed simulation framework uses the open-source tools: ROS Kinetic and Gazebo 7. We propose a system where robotic arms coordinate and collaborate to drive a screw into a plate autonomously. A move-able robot with a 3D sensing camera maps the environment and, using image recognition and localization, notifies the arms of obstacles and the locations of the screw and plate models. The arms calculate a collision-free path to the model, grasp the object, and return to a shared location.
Technical Paper

Visualization Techniques for Simulation-Based Dependent Failure Analysis

2022-03-08
2022-01-0032
Failure analysis of engineering systems typically emphasises identification and mitigation under an independent failure assumption with dependent failures treated as the exception rather than the rule. Some frameworks for addressing dependent failures through analysis appear in standards including NUREG 0492, ISO 26262, MIL 1629 A, and ARP4761 amongst others. The purpose of identifying these dependencies is to allow system analysts to determine and quantify the factors that influence dependent fault probabilities. Once defined, failure relationships can be incorporated into a Discrete Event Simulation (DES) of the system, providing a mathematically rigorous estimate of system utility (e.g., availability, reliability). Nonetheless, the output of a simulation must not only provide an expected value of performance but also allow the analyst to identify the downstream impact of probabilistic dependencies between system elements.
Technical Paper

Tool Wear Detection in Automated Drilling Operations of Aircraft Structure Components using AI Methods

2022-03-08
2022-01-0040
In fuselage barrels, the mechanical joints are fabricated using a riveting process. With the key feature of rivet bore size and quality of hole, the riveting operation can lead to serious defects with rivet play or fracture due to non-uniform load distribution. Conventional approaches of tool wear inspection lead to delayed diagnosis of tool wear, eventually leading to quality defects in the previous holes generated till the event of tool breakage. To increase the robustness of conventional tool wear inspection, the frequency of inspection is being increased leading to interruptions in productivity. Hence, online tool wear measurement and signaling systems provide efficient solutions with the elimination of direct methods of tool wear inspection. Therefore, this paper presents a feasibility study to detect tool wear in drilling operations using additional sensors combined with the use of AI methods.
Technical Paper

Information Retrieval for Aviation Applications

2022-03-08
2022-01-0044
There is a recurring need for automatic Information Retrieval (IR) from quality documents, price tags, part markings, receipts, purchase orders and technical manuals - which are otherwise non-parsable. IR coupled with search functionalities has a wide range of applications from warehouses, shop floors, marketplaces to even cockpits in the aviation sector. It helps in semi-automating workflows like document reviews, quality checks, collaborative Q&As and contextual extraction of information. These workflows make laborious tasks more intuitive and easier, thereby reducing the workload of the engineers using them. The paper describes an AI based IR platform which caters to the aforesaid scenarios in a scalable manner and integrates seamlessly with similar problems across different domains.
Technical Paper

Avionic Latch Optimization and Production using Additive Manufacturing

2022-03-08
2022-01-0048
Additive Manufacturing (AM) provides significant opportunities in aerospace applications, especially for low-volume, highly customizable parts. Besides the flexibility of part design, the approach offers significant potential of reducing product manufacturing complexity and improving in-service performance. This paper discusses an example which is in serial production at Howmet Fastening Systems. The part is a latch used in a hold-down assembly for avionics. The primary driver for the initiative was the need for increased torsional strength within the geometric constraints of the baseline design. Finite Element Analysis was used to redesign one load limiting component to improve overall torsional capability. Design for AM (DFAM) was used to successfully produce the parts without any defects with limited post-processing. Comprehensive testing included component tensile, fatigue, and microstructure characterization along with assembled part testing.
Technical Paper

Computer Aided Engineering-based Evaluation of a Purpose-built Tooling Concept for the Electroplating of Functional Coatings on Aerospace Components

2022-03-08
2022-01-0045
Industrial hard chrome plating is a rather complex, lengthy and labour-intensive process: typically, the low cathodic current efficiency of Cr plating baths results in limited deposition rates, taking an hour to deposit a thickness of 25 mm on any size of the part. In the majority of cases, the hard Cr plating process requires the use of tooling structures, making the process strongly operator-dependent and therefore, highly prone to errors. According to the Fokker Landing Gear BV team, operator-independence as well as process simplification are expected to be achieved by developing a purpose-built tooling concept. An intelligent support of employees in their increasingly complex work is also sought and thus far addressed by implementation of modern smart technologies. One of them is computer modeling and simulation, which enables to mirror the physical world in a virtual model.
Technical Paper

Super Flush Torque Controlled Screw

2022-03-08
2022-01-0017
Aerodynamic and cosmetic requirements are more and more stringent on new aircraft programs. External aircraft surfaces should ideally be free of any discontinuities and fasteners are usually local points of concern. While pins or lockbolts generally exhibit flush and smooth head surfaces, screws have inherent driving recesses which remain visible after finish paint application. Such screws are typically used in combination with anchor nuts to attach the panels closing thin wing boxes. The AeroDrive™ screw is a global solution to avoid recesses while improving mechanical characteristics of such structural joints. The AeroDrive™ screw features an additional drive head designed to break at a defined torque during installation, leaving a flush and smooth head surface.
Technical Paper

Accuracy Analysis for a Flow Line Process using a Mobile Holding Fixture for Machining CRFP Components

2022-03-08
2022-01-0041
The aerospace sector is challenged to produce airplanes more efficiently and resiliently in the future. This leads to an increasing demand for improving productivity and flexibility as well as providing solutions for sustainable developments. A bottleneck in production is the machining of large-scale components. Apart from the machining tasks, non-productive tasks like fixture adjustment, component handling, referencing and localization are performed within the machining station and can constitute up to 50% of the overall workload. In the UniFix project, Fraunhofer IFAM is participating in the development of a mobile fixture system for large-scale aircraft components, like vertical tail plane and landing flap components of the single aisle aircrafts.
Technical Paper

Skinny Fixture for Use with A Gantry Riveting Machine

2022-03-08
2022-01-0015
Electroimpact provides a solution of a gantry riveting machine which works in cooperation with a wing panel fixture. The fixture features stringer clamps along the length but also needs to reconfigure so that fasteners can be accessed by the heads of the machine. In a recent development we have made the header boards of the fixture both narrow in width and shallow in depth. This has a large operational advantage. Almost all of the fasteners can be installed without disturbing the tooling. And the motions of the tooling are considerably reduced. This was a cooperative effort of the tooling designers and the machine designers, primarily on the stringer side of the panel. How much of a time savings does this provide in comparison with the previous approach? About 20%. This paper will explain how this was done. We have already implemented this solution on ten systems and more are in progress on major aircraft programs.
Technical Paper

HSCR Steel Competes with 300M Steel

2022-03-08
2022-01-0052
Aircraft landing gears and structures have stringent performance requirements. They are subjected to severe loads, corrosion, and adverse environmental conditions, and have complex shapes which vary in thickness. 300M steel is widely used for high stress aircraft landing gears and structures. This steel is not corrosion-resistant and requires protective coatings. Plating of 300M steel involves using cadmium for corrosion resistance on external surfaces and chrome for wear resistance on internal surfaces. New restrictions have listed cadmium and chrome coatings as substances of concern due to the environmental and health risks associated with the manufacturing of cadmium and chrome coatings. Recently, a new alternative non-toxic zinc-nickel coating is being developed, however, the zinc-nickel coating does not solve the corrosion problem if it cracks.
Technical Paper

AFP 4.0

2022-03-08
2022-01-0043
There are at least three significant cost driving problems with the lamination of modern composite aerospace components. These problems are exaggerated for high production rate systems but affect all forms of automated fiber placement style lamination. 1) The amount and cost of capital equipment is extremely high. 2) The input costs are very high. 3) Autoclaves are huge and expensive and Airframers seem to dislike them a great deal. This paper’s topic will address the problems associated with item 1) Excessive capital equipment due to poor utilization of AFP equipment and the steps recently taken to increase it by a factor of at least 4. We will explain how the quality systems in place structurally hold our AFP equipment to such low utilization and explain how AFP4.0 addresses these factors.
Technical Paper

Development of Exfoliated Graphite using Innovative Chemical Technique for Aerospace Applications

2022-03-08
2022-01-0051
Several conventional methods on preparation of exfoliated graphite are in practice. However, their major limitations are poor quality of exfoliated graphite, lower yield, more expensive with higher processing time. To address these issues, a unique method for development of exfoliation of graphite using tri-solvents namely Water, Ethanol and Acetic acid is attempted in the present work. Ethanol acts as a supporting group for the long term stable dispersions of ex-graphite nanosheets. Glacial acetic acid, which readily dissolves in water, penetrates through the layers of graphite sheets and breaks the -C=C bond force between layers with the help of stirring and sonication resulting in exfoliation of graphite layers. Exfoliated graphite nanosheets were produced by using optimized mixtures of water, acetic acid and ethanol. XRD, SEM and FTIR studies have been carried out on the developed exfoliated graphite.
Technical Paper

Design and Development of a Mobile Robotic System for Aircraft Wing Fuel Tank Inspection

2022-03-08
2022-01-0042
This paper presents the design and development of a remote visual inspection robotic system for fighter jet aircraft wing fuel tank inspection. Aircraft wing fuel tank inspection is a challenging area of maintenance which requires a considerable amount of preparation and involvement of several tasks in order to conduct effective Visual and Non Destructive Inspection. The environment of an aircraft wing fuel tank poses several challenges due to the extremely hazardous nature including both physical and atmospheric constraints. The aircraft wing of a fighter jet aircraft such as the Eurofighter Typhoon is much narrower in comparison to a A320 wing and the subassemblies within the wing pose additional difficulty to access certain areas which therefore, requires disassembly of surrounding structures leading to additional time spent on the inspection. The primary focus of the robot is the design of the mobility method.
Technical Paper

Impact of stator segmentation on the performance of aerospace propulsion machines

2022-03-08
2022-01-0039
Electric machines with a high power density are required for aerospace applications. Halbach permanent magnet machines using rare earth magnets with high remanent flux density and soft magnetic materials having high saturation flux density are used to achieve the power density targets of aerospace industry. The need for high saturation flux density necessitates the use of cobalt iron lamination over the conventional silicon steel. However, cobalt iron is very expensive i.e. order of 10 in comparison to silicon steel. In addition, cobalt iron is used only for the stator lamination. Therefore, the conventional method of stator fabrication as a single piece results in enormous wastage of high performance and expensive cobalt iron lamination. Consequently, alternate topologies like segmented stators are developed to minimize the wastage of soft magnetic materials. Segmentation is achieved by splitting the stator yoke or teeth.
Technical Paper

Prediction of Residual Stresses in Direct Metal Laser Sintering of Ti-6Al-4V Alloy by Numerical simulation

2022-03-08
2022-01-0047
This paper presents the efforts made in numerical simulation of residual stresses that are induced in Direct Metal Laser Sintering (DMLS) of Ti-6Al-4V alloy structures. The DMLS process is one of the Additive manufacturing processes that is widely used in the manufacturing of metal bodies used in automotive, aerospace and medical applications. However, the major challenge faced in this process is residual stresses that are caused by large thermal gradients. The DMLS manufactured Ti-6Al-4V has lower ductility when compared to hot work ad martensite structure formed due to the rapid solidification. Residual stresses imposed in them are a key contributor to these characteristics, Despite the fact that post-processing techniques such as hot working can alleviate some of the stresses, Some residual stress effects, like as warping and thermal stress-related cracking, are unaffected by post-processing.
Technical Paper

Development of zinc and low carbon steel coatings on ABS plastic by electric arc spraying

2022-03-08
2022-01-0057
Acrylonitrile Butadiene Styrene (ABS) is one of the most sought after engineering plastic for industrial applications especially in the modern aircrafts. Due to its high strength, thermal resistance, dimensional stability, processing ability and affordability, the aircraft interior parts are made up of ABS plastic. However for heavy-duty industrial applications which require corrosion resistance, abrasion resistance and durability, the ABS plastic is not a great choice. Several studies have reported on surface metallization of ABS plastic using conventional electroplating and electroless but meagre information is available as regards use of thermal spray technique. This opens up a huge scope to conduct research in this area using most commonly used materials like zinc and low carbon steel. In the light of the above, the present work attempts to coat zinc and low carbon steel on ABS plastic using electric arc spray technique.
Technical Paper

Influence of hot extrusion on microstructure and slurry erosive behaviour of Al6061-Si3N4-Cf hybrid composite

2022-03-08
2022-01-0049
In recent decades, silicon nitride (Si3N4) & carbon fibres (Cf) have been the most popular reinforcements in the production of MMCs due to their superior wear & corrosion resistance. Al6061 is the most sought after matrix alloy owing to its excellent formability among all Al alloys. Several researchers have reported on sliding wear and corrosion properties of cast composite with Cf & Si3N4 as reinforcements but limited information is available related to slurry erosive wear behaviour of hot extruded hybrid MMCs with Cf as one of the reinforcement. In the light of above, the current work is aimed at investigating the erosive wear behaviour of Al6061 dispersed with Si3N4 (6 wt %) and Cf (1 wt %) hybrid MMC after hot extrusion. Stir casting was used to disperse electroless Ni coated with Si3N4 & copper coated with Cf in Al6061 followed by hot extrusion. Microstructural studies were conducted on cast & hot extruded alloy, it's composite & hybrid composite.
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