压杆稳定计算稳定性的概念

11•••••2•••23•••••4•][cNσσ≤=AF][cσ—35aFPFPcr•FP6bFP=FPcrcFPFPcr47••—1907—1922—19838198310454.2m17.25m565.4kN57g2.2m1.7m;ggg1.11-1.753.059•Fcr••10•••••611x)()(PcrxwFxM=12σP)()()(PxwFxMxwEI−=−=′′IEIFkPcr2=0)()(2=+′′xwkxwkxBkxAxwcossin)(+=713ABkxBkxAxwcossin)(+=0)0(=w0)(=lwB=0kxAxwsin)(=0sin=kl),2,1,0(⋅⋅⋅==nlnkπ2222PcrlEInEIkFπ==n=114I•22PcrlEIFπ=kxAxwsin)(=•lk/π=lxAxwπsin)(=815•l222PcrlEIFπ=22Pcr)2(lEIFπ=22Pcr)7.0(lEIFπ=22Pcr)5.0(lEIFπ=16•22Pcr)(lEIFµπ=l—lµ—µ—µ2.0µ0.7µ1.0µ0.5917•x-zx-y18AFrPcrc=σ•rcσAlEI22rc)(µπσ=AIi=ilµλ=22crλπσE=22=ilEµπ•1019d164642242dddi==ππ4di=1212232hbhbhiz==hhiz289.012==bbiy289.012==AIi=2022crλπσE=ilµλ=•λ•1121•••••22•σPP22crσλπσ≤=EP2PσπλE=Pλλ≥•Pλλ≥1223•λPQ235E=206GPa,σP=200MPa)λP≈80101102001020669PP≈××==πσπλEMPa)175GPa,70(p==σE8.62P≈λP2PσπλE=24Pλλ••λσba−=cra,bMPa12.1304crλσ−=Q235ƒP0λλλ≤0λλ•1325cuσ)(bsσσPλλ≥22crλπσE=P0λλλ≤λσba−=cr0λλcucrσσ=Q235,6.61,1010P≈≈λλScuσσ=26211crλσba−=22crλπσE=•211crλσba−=11,ba•PλλCλλλCMPa00668.02352crλσ−=Q235)123(c=λλ1427Cλλ≥22crλπσE=Cλλ0211crλσba−=211crλσba−=22crλπσE=28Q235ABl=2300mmb=40mmh=60mmE=206GPaλP=1011529yABzAB3011=µ123bhIz=32hAIizz==6.1321060321023000.1331=××××==−−zzilµλ16315.02=µ123hbIy=32bAIiyy==48.991040321023005.0332=××××==−−yyilµλyzλλ32P6.132λλ=zAFcrPcrσ=)(22bhEzλπ=5kN.2776.132106010401020623392=××××××=−−π1733•••••34•••ƒƒ1835•nnststPcrPPcrnFAFFn≥==σƒnstλλnstƒnst36][stPσσ≤=AF•][stσ][][stσϕσ=][][][stcrstσσσσϕn==ϕλ1][Pσϕσ≤=AF[σ]stcrnσ=1937ƒλλϕσϕ[σ]][Pσϕσ≤=AF•12338d=25mml=800mmσP=220MPaE=210GPanst=5[F]2039m1025.641025433−−×=×==di1281025.610800133=×××==−−ilµλPPσπλE=97102201021069=××=πPλλ4022cr)(lEIFµπ=234392)108001(64)1025()10210(−−×××××=ππN62096=kN096.62=stcr][nFF=kN42.125kN096.62==2141BDl=2ma=0.1m[σ]=10MPaBDFmax42,0=∑AM02330sin=⋅−⋅lFlFBDoFFBD3=AFFBD][3σϕ≤=ilBDµλ=12-347.0=ϕkN7.1531.01.0101047.06=××××≤FkN7.15max=F8032321=×=alFAxFAyFBD2243ABBCQ235BCd=40mmnst=3λc=123BC[FP]FPBACo6040cm44FPBACo6040cmBPFABFBCFB)(32PFFBC=BC8041041080122=×××==−−BCBCilµλλλcBC2345FPBACo6040cmBPFABFBCFMPa192.25MPa)00668.0235(2rc=−=λσtsrc][nAFBCσ=kN73.69][23][P==BCFFkN5.80N105.8034)1040(1025.1923236=×=×××=−π46ABNo.14CDd=20mmQ235ACDF=25kNl1=1.25ml2=0.55mE=206GPaσs=235MPans=1.45nst=1.8λP=1012447ABCDkN5.125.02530sin=×==oFFyAxxFFF==×==kN65.21866.02530cosokN252==yCDFF48•••••2549µilµλ=4λl2501AIi=λ2•µliilµλ=265122crλπσE=E•µlλ52