e894as5h - ESNC 460/894 Assignment 5: Apr. 1, 2005 due Apr....

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Unformatted text preview: ESNC 460/894 Assignment 5: Apr. 1, 2005 due Apr. 11, 2005 1(a) Using the energy balance approach, estimate the power required to produce a spot weld 3mm in diameter and 1 mm deep in low—carbon steel with a 1 sec pulse from a C02 laser. Use p = 7.86 gi’cm3 . 0t 2 0.07 ClTllfS, C = 0.? jng, k = 0.4 Wich. Tm = [8090K Li 2 13.8 kJJ‘mul, R=609ir (b) Compare the depth given in part (a) with the thermal penetration depth predicted on the basis of the uniform irradiance mode]. Remember. at this depth the temperature is only about 35% of the surface temperature. (c) According to the uniform irradiance model. how long does it take to reach T"1 at the surface for the power in (a)? .4 I r I I - if, - 7/ ' ,1 .— mam-HI I a W .l: , wme . 3, mum: —— ' QETMT v 1 / dil’imml— _u_ . — 3 A —1 SI‘_ / 2 Low carbon steel of 5 mm thickness is to be cut with a laser at :1 Speed of 1.25 mimin. with a 0.5 mm kert‘. Using energy balance, estimate the power that must be coupled into the material. Use 9 = 7.36 giam‘ , 0: = 0.07 cmzfs. c = 0.50 tigK. k = 0.4 wxch. T... = 18090; L. = 13.8 klfmol, L. = 350 kJi’mol. T. = 3135“K. R=609i 3 Mild steel is to be welded Wilh a multi—kilowatt C0; laser. Using the model of Swift—Honk and Giek, estimate the power required to produce a weld 0f2 mm width and 4.5 mm depth at l mfmin. o: = 0.09 cnfls. k = 0.4 Wich, Tm z 1809°K 4 Ileles are to be drilled in 0.5 mm thick nickel with a diameter of 0.13 mm. using a pulsed Nd:YAG laser with a 4 kW peak power output. Use energy balance equations to estimate the energy needed and the pulse length, assuming a nearly square pulse in time. Show that the time to reach vaporization at the surface is very small, based on the results of the uni form irradianee model. [3 = 8.9 glem" . C = 0.44 Jng, k = 0.91 WtemK, T”1 = 1726°K. Lr = 298 Jig. Lv = 6303Ji’g, 'I‘r : 318?°K. R2609? —mn5x.. 1 . y,- , —.-. .1112 1 "17% i. . ml! Elfilfl , m 5 , L ' ,‘I _i' W .t ,. '19:! J ...
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e894as5h - ESNC 460/894 Assignment 5: Apr. 1, 2005 due Apr....

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