材料成型原理
2 解:
??uxu0x??x?2H, ?=?uy?y=u02H, ??uuyz=z?z=–0H ?uxxy=
??x+?uy?y=0 ??u000??2H?∴小应变张量场为:?u?ij???000??2H? ???00?u?0H???等效应变场:
?ij?2(ex-e2y)+(ey-ez)2+(e23x-ez)2+6(gxy+g2yz+g2zx) =29u22034H2+9u04H2= u0H 1)??(1)z?ln2H0H?ln2 0圆柱体均匀变形 ∴??(1)r???(1)?
∴??(1)(1)r???(1)(1)????z?2??r???(1)z?0???(1)r??1??(1)12z??2ln2???(1)?23(??r???2?)?(??r???z)2?(??z????)2?ln2 (2)??(2)H0z?ln2H??ln2 0如一所求,得 ??(2)1r?????2ln2,以及??(2)?ln2 (3)累积变形
????(1)???(2)11r?????rr??2ln2?2ln2?0
??z???(1)z???(2)z?ln2?(?ln2)?0
第 11 页 共 11 页
( 材料成型原理
????(1)???(2)?2ln2
23 解: 由力平衡方程得: P(Rd?)??4?Rd(?t)sin?d?2?0???RP . 2t ?1??2???, ?3?0 ?? ?
2 ?(?1??2)2?(?2??32)?(?1??32)??1??2R2tP??s ?P??s 2tRdθσθ4 解: (a)O?B
σ2σ1
等效应力 ??2(?1??2)2?(?2??3)2?(?3??1)2?435.9MPa 2又?=200(1+?) ???1.18
?m?
?1??2??33 ?'????m
第 12 页 共 12 页
材料成型原理
??1'?166.7MPa,?2'??33.3MPa,?3'??233.3MPa
又全量应变?i?3?82,??0.13?352?,??i' ??1?1.082?2? 0.9472 (b)解法和(a)相同
O?A?O?B
O?A阶段
??217.9MPa ,???1(1)?0.0891, ?m(1)??16.7MPa
??1(1)'??133.3MPa,?2(1)'?16.7MPa,?3(1)'?116.7MPa ?1(1)??0.0823,?2(1)?0.0103,?3(1)?0.0721 又?(2)????(1),
? A→B过程 ?1(2)?1.0006,?2(2)??0.1249,?3(2)?0.8753
则全过程中全量主应变?i??i(2)??i(2) 即 ?1??0.0823?1.0006?0.9183 ?2?0.010?3?(0.012?4?9) ?3?0.072?1
0.0.08?753 0.5 解:已知?x??60MPa,?y??30MPa,?z?0,?xy?300MPa,?zx??zy?0 则?m??x??y??z3??30MPa
?i'??i??m
??x??30MPa,?y?0MPa,?z?30MPa
'''?ij,又已知d?x???,可得 根据增量形式levy-Mises本构方程:d?ij?d??
p'd?x?x?d?y??d?zy??d?xyz??d?yzxy??d?xzyz??d??xz???? ?3030 ?d?y?d?yz?d?zx?0 , d?z??z?d??30??30??
第 13 页 共 13 页
材料成型原理
d?xy??xy?d??300??30?0.58?
???? 则应变增量张量为: 0.58????0'0.58?000? 0??????ij 塑性功增量密度:dw??ij?则有塑性功增量密度为:
dw??x'?d?x??y'?d?y??z'?d?z?2?xy?d?xy?2?yz?d?yz?2?zx?d?zx?80?
6 解:(1)A:圆柱部分
P??r2P?rP?2rP?r??0, ??? ?r?0, ?z???0
2?r?t2t2tt 则点A屈服时:?1????P?rP?r,?2??z?,?3?0 t2t 有(?1??2)2?(?2??3)2?(?3??1)2?2?s2 ?PA? B:球面部分
P?????(rd?)2?4???rd??tsin?,0 则B点屈服时:?1??2????2t?s 3rd?2Pr 2tP?r,?3?0 2t (?1??2)2?(?2??3)2?(?3??1)2?2?s2 ?PB?2?s
因为PB>PA,所以A点先屈服,即圆筒部分先屈服。 (2)屈服时P?tr2rP?rP?r ?s,且?r?0,?z?,???2tt3t3' 则?m??r?????z?P?rP?rP?r' ??r'? ,?z'?0?,??2t2t2t?ij,得 根据d?ij?d?? d?r??d??,d?z?0, 且d?r?0,d???0 又有等效应变增量:
第 14 页 共 14 页
材料成型原理
d??2(d?z?d??)2?(d???d?r)2?(d?r?d?z)2?? 3392? ?, ?d?r??22 即(d?r)2?(2d?r)2?(d?r)2????? 对应的应变增量张量为:?????
7 解: r方向的静力平衡方程
3?200000?0??0?
?3??2?? ?r?rd??H?(?r?d?r)(r?dr)d??H?2??sin ?d?r?d??dr?H?2?fdr?rd??0 2????rrdr?2?fdr Hdr H 假设轴对称均匀变形 ??r???,d?r???f ?r,?z都为压应力,且?z??r 令?1???r,?3???z 由屈服准则得:
?1??3??z??r???,?d?r?d?z ?d?z??2?fdrr??z??2?f??C HH 边界条件:r?R0时,?r?0,?z??? ?C????2?? ?P?R0r??z?2????? HHR0) Hrd??sin??d?
rsin?1?R02?R002?rdr?z??(??2?8 解:在圆锥面上取单元体,令OA=r,d?? 沿?方向列平衡方程 (???d??)(r?dr)d??t?2?? ?d????(?????)drd?t?sin????r?d??t?0 sin?2dr r第 15 页 共 15 页
材料成型原理
因为??为拉应力,??为压应力,?1???,?3???? 由Mises塑性条件:?1??3?????????
dr???????lnr?C rDD 边界条件:r?0时,???0?C???ln0
22 ∴d?????? ∴?????lnDD0d,则当r?0时,?????ln0
d022r ∴拉深力P??d0t????d0t????ln
D0 d0 第 16 页 共 16 页