Tensile strength(Catastrophic failure area =10 mmx5 mm=50x 10-6 m2 max load (tensile strength x area) )= safety factor =(900MPaX50X106m2)÷1.6 =28.1kN (tensile fracture at load>28. 1 kN) 202128 & Dr Jonathan c.y. Chung: NDE
Tensile strength (Catastrophic failure) area = 10 mm x 5 mm = 50 x 10-6 m2 max. load = (tensile strength x area) safety factor = (900MPa x 50 x 10-6 m2 ) 1.6 = 28.1 kN (tensile fracture at load > 28.1 kN) ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖6
Fracture ToughneSS (require information of crack length) MC=ao vaa Assume geometric correction factor, a=1 max=Kc/V(πa) Max load oXA÷( safety factor) KIc /v(a)x A-(safety factor =40 MPam/(31416Xa)×50×106m2÷ safety factor When a=2mm, max load=(2000÷0.07927)/1.5=16.8kN When a=1mm, max load=(2000÷0.05605)15=236kN When a=0.1mm, max load=(2000÷0.01772)1.5=752kN 202128 & Dr Jonathan c.y. Chung: NDE
Fracture Toughness (require information of crack length) KIC = (a) Assume geometric correction factor, = 1 max = KIC /(a) Max load = x A (safety factor) = KIC /(a) x A (safety factor) = 40MPam /(3.1416 x a) x 50 x 10-6 m2 (safety factor) When a = 2 mm, max load = (2000 0.07927)/1.5 = 16.8 kN When a = 1 mm, max load = (2000 0.05605)/1.5 = 23.6 kN When a = 0.1 mm, max load = (2000 0.01772)/1.5 = 75.2 kN ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖7
NDE methods for location of defects Surface defects Internal defects detection Magnetic particle method detection Radiographic methods Visual inspection 8 Electromagnetic methods 冷 Eddy current method o liquid penetrant test &o Barkhausen Noise Inspection ☆ Magnetic particle Principle method Material defects(grinding damage re-tempering burn, Re- g burn residue stresses 令 Acoustic methods 202128 & Dr Jonathan c.y. Chung: NDE
NDE methods for location of defects Surface defects detection ❖Visual inspection ❖Liquid penetrant test ❖Magnetic particle method ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖8 Internal defects detection ❖ Magnetic particle method ❖ Radiographic methods ❖ Electromagnetic methods ❖ Eddy current method ❖ Barkhausen Noise Inspection Principle Material defects (grinding damage, re-tempering burn, Rehardening burn, residue stresses ❖ Acoustic methods
Visual inspection It should never be omitted Use low-power magnifying glass or microscopes (remember to take permanent photographic record ■ Surface roughness Touch inspection using finger along the surface(2-3 cm/s Light reflection method ☆ No-parallex method ■ Penetrant test 202128 & Dr Jonathan c.y. Chung: NDE ◆9
Visual inspection ◼ It should never be omitted. ◼ Use low-power magnifying glass or microscopes (remember to take permanent photographic record) ◼ Surface roughness: ❖Touch inspection using finger along the surface (2-3 cm/s.) ❖Light reflection method ❖No-parallex method ◼ Penetrant test ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖9
Penetrant test Suitable for locating surface discontinuities, such as cracks seams, laps, laminations in non-porous materials Applicable to in-process final, and maintenance inspection ■ ASTME165 General procedure: Thoroughly clean the surface Apply penetrant on the surface Liquid penetrant enter small openings by capillary action Remove liquid completely and apply developer ( dry or wet uThe penetant bleed out onto the surface showing the location of the surface defect 202128 & Dr Jonathan c.Y. Chung: NDE 今10
Penetrant test ◼ Suitable for locating surface discontinuities, such as cracks, seams, laps, laminations in non-porous materials. ◼ Applicable to in-process, final, and maintenance inspection. ◼ ASTM E 165 General procedure: ◼ Thoroughly clean the surface ◼ Apply penetrant on the surface ◼ Liquid penetrant enter small openings by capillary action ◼ Remove liquid completely and apply developer (dry or wet) ◼ The penetant bleed out onto the surface showing the location of the surface defect ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖10