Investigation and Modeling of Flag Generation in Honeycomb Sandwich Panel Machining

Author(s):  
Derek M. Yip-Hoi ◽  
David D. Gill

Light weight honeycomb structures lend themselves to important applications in aerospace. These range from aerodynamic and structural components such as wing edges, flaps, rotor blades and engine cowlings, to aircraft interior structures such as overhead luggage bins, compartment liners, bulkheads and the monument structures found in galleys and lavatory areas. Often the honeycomb is formed into a composite ply sandwich with fiberglass face sheets bonded to the honeycomb core. These panels are cut to shape using CNC routers and specially designed cutting tools. However, the quality of the cuts generated even with these special tools leaves much to be desired. The low stiffness of the structure leads to imperfections such as fraying of the cut face sheet edges and the generation of flags along the cut honeycomb edge. These impact the ease of assembly and often require manually intensive reworking to mitigate. The cutting of honeycomb structures and sandwich panels is challenging due to low stiffness, anisotropic mechanical properties and a high proportion of interrupted cutting due to the air voids that are present. The cutting mechanics are not well understood at this time. This paper presents findings from the study of cutting of honeycomb sandwich panels using high speed videography and correlates these with results of geometric modeling of the engagement between the cutter and workpiece. The study includes the impact of the trajectory of the tool path through the cell structures on the generation of flagging. It also reports on the effects of two different cutting tool geometries and the introduction of a lead angle on the size and structure of the flags generated. These findings present the case for a research regime similar to the one completed for solid metals, into modeling the mechanics behind machining honeycomb structures. This will help manufacturers using these materials to make better choices in the tools, cutting parameters and machining strategies that they employ in their process planning.

2011 ◽  
Vol 675-677 ◽  
pp. 547-550
Author(s):  
Hong Yang Zhao ◽  
Dong Ying Ju ◽  
Yasumi Ito ◽  
Tetsuya Nemoto ◽  
Yoshie Takahashi

This paper describes the results of an experimental investigation on the drop off impact test on a range of sandwich panels. The magnesium alloy sandwich panels were fabricated with rolled sheets at different thickness by pressing and bonding method. Out-plane compression test was employed to obtain its basic deformation-force behavior. The impact experiments were carried out in which a steel cylinder was dropped off at various height levels, ranging from 0.5m to 1.5 cm to impact the panel. A high speed camera was employed to take pictures at 20 thousand frames per second and the low-velocity impact response on the sandwich panels is recorded with a dynamic force senor under the panel simultaneously. The shock response with time and the impact absorption energy were analyzed and compared. The results of this study proved that the magnesium alloy honeycomb sandwich panels have good impact energy absorption performance.


Author(s):  
Eyyup Aras ◽  
Derek Yip-Hoi

Helical milling is a 3-axis machining operation where a cutting tool is feed along a helix. This operation is used in ramp-in and ramp-out moves when the cutting tool first engages the workpiece, for contouring and for hole machining. It is increasingly finding application as a means for roughing large amounts of material during high speed machining. Modeling the helical milling process requires cutter/workpiece engagements (CWEs) geometry in order to predict cutting forces. The calculation of these engagements is challenging due to the complicated and changing intersection geometry that occurs between the cutter and the in-process workpiece. In this paper we present a geometric modeling methodology for finding engagements during helical milling with flat end mills. A mapping technique has been developed that transforms a polyhedral model of the removal volume from Euclidean space to a parametric space defined by location along the tool path, engagement angle and the depth-of-cut. As a result, intersection operations are reduced to first order plane-plane intersections. This approach reduces the complexity of the cutter/workpiece intersections and also eliminates robustness problems found in standard polyhedral modeling and improves accuracy over the Z-buffer technique. The reported method has been implemented and tested using a combination of commercial applications. This paper highlights ongoing collaborative research into developing a Virtual Machining System.


2017 ◽  
Vol 62 (3) ◽  
pp. 1771-1777 ◽  
Author(s):  
Y. Allwin Roy ◽  
K. Gobivel ◽  
K.S. Vijay Sekar ◽  
S. Suresh Kumar

AbstractCarbon fiber reinforced polymeric (CFRP) composite materials are widely used in aerospace, automobile and biomedical industries due to their high strength to weight ratio, corrosion resistance and durability. High speed machining (HSM) of CFRP material is needed to study the impact of cutting parameters on cutting forces and chip microstructure which offer vital inputs to the machinability and deformation characteristics of the material. In this work, the orthogonal machining of CFRP was conducted by varying the cutting parameters such as cutting speed and feed rate at high cutting speed/feed rate ranges up to 346 m/min/ 0.446 mm/rev. The impact of the cutting parameters on cutting forces (principal cutting, feed and thrust forces) and chip microstructure were analyzed. A significant impact on thrust forces and chip segmentation pattern was seen at higher feed rates and low cutting speeds.


2011 ◽  
Vol 188 ◽  
pp. 542-548 ◽  
Author(s):  
Jie Liu

High-speed machining requires the support of high intelligent CAM software as well as customized machining strategies and properly selected machining parameters. Only by combining the two can the advantage of high-speed machining be made full use of. Compared to ordinary NC cutting, high-speed machining has special requirements for process strategies, CAM system and tool path. A complete tool path includes approaching/retracting tool, moving tool and tool path. Based on the above principles, a mould part is successfully processed using the PowerMILL software at the high-speed machining centre of DMG-DMU40T. The maximum hardness of the mould part is HRC50. There’s a 30 degree corner in the cavity with a transition radius of 3mm. The whole process can be divided into three stages: rough, semi-finish and finish machining and each stage involves the selection of tool path, the selection of tool, the selection of cutting parameters (including spindle speed, feed speed and depth of cut), and the application of PowerMILL specific machining methods (such as Race-line machining, rest roughing, automatic trochoidal machining, 3D offset finishing and etc).


Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1526
Author(s):  
Cheng-Hsien Kuo ◽  
Zi-Yi Lin

Most aerospace parts are thin walled and made of aluminum or titanium alloy that is machined to the required shape and dimensions. Deformation is a common issue. Although the reduced cutting forces used in high-speed milling generate low residual stress, the problem of deformation cannot be completely resolved. In this work, we emphasized that choosing the correct cutting parameters and machining techniques could increase the cutting performance and surface quality and reduce the deformation of thin plates. In this study, a part made of a thin 6061 aluminum alloy plate was machined by high-speed milling (HSM), and a Taguchi L16 orthogonal array was used to optimize the following parameters: linear velocity, feed per tooth, cutting depth, cutting width, and toolpath. The impact of cutting parameters on the degree of deformation, surface roughness, as well as the cutting force on the thin plate were all investigated. The results showed that the experimental parameters for the optimal degree of deformation were A1 (linear velocity 450 mm/min), B1 (feed per tooth 0.06 mm/tooth), C1 (cutting depth 0.3 mm), D4 (cutting width 70%), and E4 (rough zigzag). Feed per tooth was the most significant control factor, with a contribution as high as 63.5%. It should also be mentioned that, according to the factor response of deformation, there was a lower value of feed per tooth and less deformation. Furthermore, the feed per tooth and the cutting depth decreased and the surface roughness increased. The cutting force rose or fell with an increase or decrease of cutting depth.


Author(s):  
T. Mugilan ◽  
T. Alwarsamy

Material removal process for dies, moulds and additionally diverse aircraft parts can be made possible by the highspeed end milling operation. Devious cutting forces are created by the impact of various cutting parameters in course with high speed milling process. Due to this phenomenon the wear and chatter of tool can occur. Cutting force prediction is useful method to reduce the chatter occurrence during the machining of hardest materials. DEFORM 3D is an important simulation software which is used for the analysis of complicated metal removal processes. In this work, the tool insert was designed by Solid Works modelling software. The FEM simulation of high-speed end milling of Titanium-Vanadium based alloy was carried out in Deform 3D simulation software to obtain the cutting forces. The material behaviour was modelled with a classical constitutive material equation and was applied in the FEM code to predict the effective stress, strain, temperature and cutting forces towards the impact of cutting parameters. Analysis of variance is achieved to determine the impact of cutting forces with help of Taguchi method in Minitab-17. L16 orthogonal array was used to conduct the analysis of high speed end milling.


2011 ◽  
Vol 337 ◽  
pp. 479-488
Author(s):  
Nurhaniza Mohamad ◽  
M.K.A.M. Arifin ◽  
Aidy Ali ◽  
Faizal Mustapha

The thin-web structure component is widely used in aviation and aerospace industries with the reason of light weight and high performance. However, the thin-web components are tending to deflect because of their poor rigidity and the effect of cutting force during cutting process. It is required to perform of high-speed machining that can remove the large number of material in a shorter time in order to allow machining of such structure. The performance of high-speed machining operation is restricted by the static and dynamic stiffness of the tool and part that can cause some problems such as regenerative chatter and ‘push-off’. The tool path plays an important function to avoid the problem occurs as it assists to reduce the workpiece vibration during machining. The optimization of tool path is done by determining the element removal sequences and the materials removal are implemented using milling cutter. The maximum deflection for each element removed is recorded in order to define the optimum solution of element removal sequences. The analysis shows that there are significant effects of workpiece stiffness with relation to the cutting parameters setting.


2015 ◽  
Vol 1119 ◽  
pp. 812-815
Author(s):  
Cong Bo Ma ◽  
Yan Wei Wang ◽  
Guang Ping Zou ◽  
Xuan Du

It’s very important to select appropriate dimensions for manufacture of honeycomb sandwich. In this paper, the experimental and theoretical methods were compared. The results are proved that the theoretical formula can be applied to engineering design. The impact factor of staties mechanical properties of honeycomb panels also was studied. And a theoretical basis for the design of honeycomb sandwich panels is provided.


Author(s):  
Hongwei Zhu ◽  
Changfang Zhao

The aim of this work was to study the anti-penetration effect of sandwich composite armor with ceramic honeycomb structures filled with aluminum alloy under the impact of high-speed projectiles. The finite element software ABAQUS was used to conduct numerical simulation research on the process of a standard 12.7-mm projectile penetrating sandwich composite armor. The armor-piercing projectile model was simplified as a rigid body. The numerical simulation models were applied to three different sandwich composite armor structures (A, B, and C), each with a total armor thickness of 25 mm. The penetration resistance of the three kinds of composite armor was studied. We obtained velocity curves for the rigid projectile penetrating the different structures. The failure forms and penetration resistance characteristics of the three composite armor structures adopted in this paper were analyzed. In addition, the velocity reduction ratio is proposed as an index to evaluate the penetration resistance performance of the armor. The simulation results revealed decreasing rates of projectile speed in the structures A, B, and C of 69.6%, 91.1%, and 100%, respectively. The third composite armor (structure C) designed here has excellent penetration resistance and can block the penetration of a high-speed (818m/s) rigid projectile. This study can provide some reference for the application of laminated armor material in anti-penetration protection structures.


2021 ◽  
Author(s):  
Yanjie Du ◽  
Caixu Yue ◽  
Xiaochen Li ◽  
Xianli Liu ◽  
Steven Y. Liang

Abstract Aiming at the breakage of tool and low precision of the machined surface in the high-speed milling process of titanium alloy, damage mechanics is used to reveal the formation mechanism of tool fatigue breakage during the milling and determine the critical condition of tool breakage. Cutting edge chipping caused by random impact fracture during the evolution of tool damage is the main failure form of tool fatigue breakage. Based on continuous damage mechanics, fatigue crack growth theory and sliding crack energy balance equation, the crack growth law of tool material is studied under different cutting impact, and the initial damage value and critical damage value of tool material fracture based on the interval method are obtained. And the impact fracture limit conditions of the end mill edge are established including cutting parameters, material hardness, tool damage, tool wear, and cutting impact, which provide a theoretical basis for determining the cutting parameters. A titanium alloy milling experiment is carried out to define the impact damage morphology of the tool in different states after the tool is damaged. The obtained tool safety area range is verified, and the research results provide parameter optimization for the high-speed and high-efficiency milling titanium alloy process.


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