Fracture mechanical behaviour of laser beam-welded AA2198 butt joints and integral structures

2015 ◽  
Vol 6 (6) ◽  
pp. 787-798 ◽  
Author(s):  
Nikolai Kashaev ◽  
Stefan Riekehr ◽  
Kay Erdmann ◽  
Alexandre Amorim Carvalho ◽  
Maxim Nurgaliev ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Laser Beam ◽  
Damage Tolerance ◽  
Fracture Behaviour ◽  
Butt Joints ◽  
Metallic Structures ◽  
Mechanical Fracture ◽  
Content Type ◽  
Integral Structures

Purpose – Composite materials and metallic structures already compete for the next generation of single-aisle aircraft. Despite the good mechanical properties of composite materials metallic structures offer challenging properties and high cost effectiveness via the automation in manufacturing, especially when metallic structures will be welded. In this domain, metallic aircraft structures will require weight savings of approximately 20 per cent to increase the efficiency and reduce the CO2 emission by the same amount. Laser beam welding of high-strength Al-Li alloy AA2198 represents a promising method of providing a breakthrough response to the challenges of lightweight design in aircraft applications. The key factor for the application of laser-welded AA2198 structures is the availability of reliable data for the assessment of their damage tolerance behaviour. The paper aims to discuss these issues. Design/methodology/approach – In the presented research, the mechanical properties concerning the quasi-static tensile and fracture toughness (R-curve) of laser beam-welded AA2198 butt joints are investigated. In the next step, a systematic analysis to clarify the deformation and fracture behaviour of the laser beam-welded AA2198 four-stringer panels is conducted. Findings – AA2198 offers better resistance against fracture than the well-known AA2024 alloy. It is possible to weld AA2198 with good results, and the welds also exhibit a higher fracture resistance than AA2024 base material (BM). Welded AA2198 four-stringer panels exhibit a residual strength behaviour superior to that of the flat BM panel. Originality/value – The present study is undertaken on the third-generation airframe-quality Al-Li alloy AA2198 with the main emphasis to investigate the mechanical fracture behaviour of AA2198 BMs, laser beam-welded joints and laser beam-welded integral structures. Studies investigating the damage tolerance of welded integral structures of Al-Li alloys are scarce.

scholarly journals Fatigue, Fatigue Crack Propagation and Mechanical Fracture Behaviour of Laser Beam-Welded AZ31 Magnesium Sheets

2014 ◽  
Vol 783-786 ◽  
pp. 2310-2315 ◽  
Author(s):  
Nikolai Kashaev ◽  
Stefan Riekehr ◽  
Manfred Horstmann ◽  
Volker Ventzke
Keyword(s):  
Fatigue Crack ◽  
Laser Beam ◽  
Crack Propagation ◽  
Magnesium Alloys ◽  
Fatigue Crack Propagation ◽  
Fracture Behaviour ◽  
Base Material ◽  
Lightweight Construction ◽  
Mechanical Fracture ◽  
Structural Applications

Weight reduction is the main driving force in automotive and aircraft structural design. As a result, magnesium alloys, with their high potential for lightweight construction, have attracted a considerable amount of industrial attention. The determining criterion for the structural applications of magnesium alloys is the availability of efficient joining technologies for the construction of lightweight structures and the availability of reliable data for the assessment of their damage tolerance behaviour. Laser beam welding (LBW), as a high-speed and easily controllable process, allows the welding of complex geometric forms that are optimised in terms of mechanical stiffness, strength, production velocity and visual quality. The work accomplished in this study addresses the challenges of the LBW process for typical joint configurations using the magnesium alloy AZ31HP: butt joints, T joints and overlap joints. LBW processes were developed for use with a 3.3-kW Nd:YAG laser to optimise the mechanical performance of such joints with respect to tensile strength, fatigue, fatigue crack propagation and mechanical fracture behaviour. The relationships between the LBW process and the microstructural and mechanical properties of welds were established. Compared to state-of-the-art aerospace alloys, AZ31HP demonstrates that magnesium alloys have potential for use in structural applications, with AZ31HP being comparable to AA2024T351 and AA6061T6. Welded AZ31HP exhibits better crack resistance than the base material, so fully welded integral structures made from magnesium alloys can be used in lightweight construction.

Effect of the heat treatment on corrosion and mechanical properties of CoCrMo alloys manufactured by selective laser melting

2018 ◽  
Vol 24 (7) ◽  
pp. 1235-1244 ◽  
Author(s):  
Mingkang Zhang ◽  
Yongqiang Yang ◽  
Changhui Song ◽  
Yuchao Bai ◽  
Zefeng Xiao
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Streptococcus Mutans ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
Mechanical Fracture ◽  
Content Type ◽  
Astm F75 ◽  
Cocrmo Alloys

PurposeThis study aims to focus on the heat treatment influence on the corrosion resistance, adhesion of Streptococcus mutans and mechanical properties of CoCrMo alloys manufactured by the selective laser melting (SLM). Design/methodology/approachCoCrMo alloys were manufactured using the Dimetal-100 machine. X-ray diffraction (XRD), metallographic analysis, scanning electron microscopy (SEM), electrochemical corrosion, Vickers microhardness and tensile tests were used to characterize SLM-produced CoCrMo alloys and compare them with the ones manufactured by casting and with the ASTM F75 standard. FindingsThe electrochemical results showed that SLM900 samples had the best corrosion resistance in artificial saliva. The adhesion results showed least propagation and overall quantity of Streptococcus mutans on the SLM900 sample. The microhardness, tensile and yield strength of As-SLM, SLM900 and SLM1200D samples were measured according to the ASTM F75 standard. The elongation of SLM900 was less than 8 per cent, which does not meet the standard specifications. Analysis of the fracture morphology showed that the fracture mechanisms of As-SLM and SLM1200D belong to the quasi-cleavage fracture type, and the mechanical fracture mechanism of SLM900 can be characterized as brittle fracture. Originality/valueThis paper presents the adhesion properties of Streptococcus mutans on the surface of CoCrMo alloys manufactured by SLM and proposes how to regulate the effect of the heat treatment on the corrosion resistance and mechanical properties of CoCrMo alloys manufactured by SLM.

Embedded carbon nanotube thread piezoresistive strain sensor performance

Sensor Review ◽  
2014 ◽  
Vol 34 (2) ◽  
pp. 209-219 ◽  
Author(s):  
Mark Schulz ◽  
Yi Song ◽  
Adam Hehr ◽  
Vesselin Shanov
Keyword(s):  
Carbon Nanotube ◽  
Composite Materials ◽  
Strain Sensor ◽  
Temperature Stability ◽  
Gauge Factor ◽  
Strain Sensing ◽  
Metallic Structures ◽  
Content Type ◽  
Sensing Properties ◽  
Sensor Performance

Purpose – Carbon nanotube (CNT) thread ' s piezoresisitive strain sensing properties of gauge factor, linearity, hysteresis, consistency, temperature stability, and bandwidth were evaluated. This evaluation was motivated by little information in literature combined with the need to understand these properties for commercial use. The paper aims to discuss these issues. Design/methodology/approach – The study here analyzes as-spun CNT thread built into unidirectional glass fiber composites and mounted onto aluminium beams with epoxy to evaluate strain sensing properties. The analyses utilize known sensor parameter definitions to quantify sensor performance. Findings – CNT thread can provide reliable and robust strain measurements for composite and metallic structures. The strain sensor performance meets or exceeds other strain sensors in performance. Research limitations/implications – CNT thread ' s piezoresistive effect is not well understood in terms of Poisson ' s ratio and nanotube contact. More research needs to be carried out to better understand this relationship and optimize the sensor thread. Practical implications – CNT thread can be utilized as a robust strain sensor for composite and metallic structures. It can also be built into composite materials for embedded strain and damage monitoring. By monitoring composite materials with the sensor thread, reliability will significantly increase. In turn, this will lower safety factors and revolutionize inspection methods for composite materials. Originality/value – This paper is the first to comprehensively evaluate key strain sensing properties of CNT thread. With all this strain sensor information in one spot, this should help expedite the use of this technology in other research and industry.

Mechanical properties evaluation of T800 carbon fiber reinforced hybrid composite embedded with silicon carbide microparticles

2018 ◽  
Vol 14 (3) ◽  
pp. 589-608 ◽  
Author(s):  
Rakesh Potluri
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Composite Materials ◽  
Hybrid Composite ◽  
Hybrid Composites ◽  
Fiber Reinforced ◽  
Shear Properties ◽  
Content Type ◽  
Volume Fractions ◽  
Transverse Tensile

PurposeThe purpose of this paper is to study the effect of the addition of silicon carbide (SiC) microparticles and their contributions regarding the tensile and shear properties of the T800 fiber reinforced polymer composite at various fiber volume fractions. The tensile and shear properties of the hybrid composites where continuous T800 fibers are used as reinforcements in an epoxy matrix embedded with SiC microparticles have been studied.Design/methodology/approachThe results were obtained by implementing a micromechanics approach assuming a uniform distribution of reinforcements and considering one unit cell from the whole array. Using the two-step homogenization process, the properties of the materials were determined by using the finite element analysis (FEA). The predicted elastic properties from FEA were compared with the analytical results. The analytical models were implemented in the MATLAB Software. The FEA was performed in ANSYS APDL.FindingsThe mechanical properties of the hybrid composite had increased when compared with the properties of the conventional FRP. The results suggest that SiC particles are a good reinforcement for enhancing the transverse and shear properties of the considered fiber reinforced epoxy composite. The microparticle embedment has significant effect on the transverse tensile properties as well as in-plane and out-of-plane shear properties.Research limitations/implicationsThis is significant because improving the properties of the composite materials using different methods is of high interest in the materials community. Using this study people can work on the process of including different type of microparticles in to their composite designs and improve their performance characteristics. The major influence of the particles can be seen only at lower volume fractions of the fiber in the composite. Only FEA and analytical methods were used for the study.Practical implicationsMaterial property improvements lead to more advanced designs for aerospace and defense structures, which allow for high performance under unpredictable conditions.Originality/valueThis type of study proves that the embedment of different microparticles is a method that can be used for improving the properties of the composite materials. The improvement of the transverse and shear properties will be useful especially in the design of shell structures in the different engineering applications.

An investigation on cutting of the MWCNTs doped composite plates by CO2 laser beam

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ferhat Ceritbinmez ◽  
Ahmet Yapici
Keyword(s):  
Composite Materials ◽  
Laser Beam ◽  
Laser Power ◽  
Laser Cutting ◽  
Fiber Composite ◽  
Cutting Speed ◽  
Multiwall Carbon Nanotubes ◽  
Composite Plates ◽  
Cutting Parameters ◽  
Content Type

Purpose The purpose of this study is to obtain strong materials with multiwall carbon nanotubes (MWCNTs) doped and investigate laser cut of MWCNTs also find the effect of the laser cutting parameters on composite materials. Design/methodology/approach The laminated composite plates were manufactured by using a vacuum infusion process. The mechanical properties of the composite materials produced were determined according to American Society for Testing and Materials (ASTM) D3039M, ASTM D3171, ASTM D 792 and ASTM D2583. A 130 Watts carbondioxide (CO2) laser cutting machine was used for drilling the two different composite plates with a thickness of 1.6–1.5 mm. Three variables were considered as process parameters including laser power (in three levels of 84.50, 104.00 and 127.40 W), cutting speed (in three levels of 4, 6, 8 mm/s) and 14 mm fixed focal position. Findings The fibers could not be cut due to insufficient melting in the experiments performed using 84.50 and 104.00 W laser power but the cutting was successfully completed when the laser power was 127.40 W. However, as the cutting speed increased, the contact time of the laser beam with the material decreased, so the kerf decreased, but the increased laser power created a thermal effect, causing an increase in hardness around the cutting surface. This increase was lower in MWCNTs doped composites compared to pure composites. It has been found that the addition of nanoparticles to layered glass fiber composite materials played an effective role in the strength of the material and affected the CO2 laser cutting quality. Originality/value This study is a unique study in which the CO2 laser cutting method of MWCNT-doped composite materials was investigated and the machinability without cutting errors, such as delamination, splitting, distortion and burring using the most suitable laser cutting parameters was revealed.

Aging of polymer composite materials under loading. (See Beginning in #10-2020)

2020 ◽  
pp. 2-12
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Polymer Composite ◽  
Polymer Composite Materials ◽  
Cyclic Loads ◽  
Reinforced Plastics ◽  
Water Exposure ◽  
Laboratory Conditions ◽  
Bending Loads ◽  
Moisture Conditions

A study review of aging polymer composite materials (PCM) under different heat-moisture conditions or water exposure with the sequential or parallel influence of static or cyclic loads in laboratory conditions is presented. The influence of tension and bending loads is compared. Conditions of the different load influence on parameters of carbon-reinforced plastics and glass-reinforced plastics are discussed. Equipment and units for climatic tests of PCM under loading are described. Simulation examples of indices of mechanical properties of PCM under the influence of environment and loads are shown.

Aging of polymer composite materials under loading

2020 ◽  
pp. 7-18
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Polymer Composite ◽  
Polymer Composite Materials ◽  
Cyclic Loads ◽  
Reinforced Plastics ◽  
Water Exposure ◽  
Laboratory Conditions ◽  
Bending Loads ◽  
Moisture Conditions

A study review of aging polymer composite materials (PCM) under different heat-moisture conditions or water exposure with the sequential or parallel influence of static or cyclic loads in laboratory conditions is presented. The influence of tension and bending loads is compared. Conditions of the different load influence on parameters of carbon-reinforced plastics and glass-reinforced plastics are discussed. Equipment and units for climatic tests of PCM under loading are described. Simulation examples of indices of mechanical properties of PCM under the influence of environment and loads are shown.

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