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NGHIEN CXAY DI/NG MO HINH PHAN TLT HU'U HAN NGHIEN CLTU ON RUNG KHUNG V6 TO KHACH 29 C H BUILDING FINITE ELEMENT MODELS TO STUDY NOISE AND VIBRATION OF THE STRUCTURE BODY OF BUS 29 SEATS Nguyin Thanh Quang', Le Quynh Mai', Nguyin Trpng Hoan^ 'Cdng ty Mekong Auto ^Trfldng Dai hpe Bach khoa Ha NdL Hien nay, cdc phUdng tien giao thong dUdng bg van tdi hdnh khach chiem Uu thevd ngdy cdng phdt trien theo nhu cdu giao thong van tdi cua Viet Nam Xe chd khdeh co nhieu Uu diem bdi toe di chuyen cao, chgy tren nhieu tuyen dUdng ngdn, trung binh vd ddi vdi chdt lUgng van chuyen cao Logixe to 29 chd ngoi sdn xudt nUdc co nhu cdu thi trUdng ldn, da dUdc nhom tdc gid sd diing ldm doi tugng nghien cdu Bdi bdo trinh hdy ket qud xdy dUng mo hinh on rung khung vo to khach 29 chd sdn xuat lap rdp tai Viet Nam vdi mo hinh tinh todn: Mo hinh phdn td hdu hgn (PTHH) ket cdu thdn vo xe (structure model) vd mo hinh PTHH khong khoang xe (airborn model) Cdu true khung vo xe vd cdc kich thudc cua mo hinh dUdc xdy dUng bang ky thuat ScanSD todn bg vo xe vd sd dung phdn men chuyen dung Rapidform kit noi vdi phdn mem Ansys detinh todn Chinh vi vgy kich thUdc vd hinh ddngmo hinh PTHH cua khung vo xe gdn vdi kich thUdc vd hinh ddng thiic te ddn den viec tim ket qud bdi todn tiet kiem thdi gian vd chinh xdc hdn Tfl khda: Mo hinh PTHH, on rung, khung vo, xe khdeh 29 cho ABSTRACT Nowadays, the transportation vehicles are dominant and growing accord vi>ith need using transportation of Vietnam The transportation vehicles have many advantages by high speed, running on tnany routes short, medium and long roads with high quality transport The bus 29 seats made in Vietnam wdh large market demand has been the authors using as research subjects This paper presents the results of Building finite element models of the structure body of bus 29 seats made in Vietnam with calculate models: the frame body (structure model) and the air body (airborne model) The structure body dimensions of the bus are using by technical ScanSD and using the Rapidform software connection with Ansys software to calculate Therefore, the results obtain save time and more accurately Keywords: The models of finite element, noise and vibration, the structure body, vehicle 29 seats ^ H TAP CHi CO KHi VIET NAM • Sd (Thang nam 2013) NGHIEN CUfU-TRAO D O I TONG QUAN VAN DE NGHIEN CCU Theo thdng ke tong so Iflpng xe khach tham gia giao thdng tai Viet Nam dang la 99,452 phfldng lien (sd lieu 2011) dd: - Xe khach tfl 10 den 16 eho: 57,354 chiec (chiem 58%) - Xe khach tfl 17 den 25 chd: 5,681 ehiee (chiem 6%) - Xe khach tfl 26 den 46 chd: 24,645 chiee (ehiem 25%) - Xe khach tren 46 cho: 11,772 ehiee (chiem 11%) Trong dd: Sd lflpng xe khach tfl 26 den 46 cho chiem khoang V4 tong sd Iflpng xe khach eua cl nfldc, chung Ioai xe rat phfl hpp vdi hinh thflc van chuyen lien tinh cd nhflng flu diem ve s6 ngfldi van chuyen trung binh, tinh kinh te mpt lan van ehuyen, dieu kien dia hinh dfldng xa d Viet Nam Do do, nhdm nghien cflu da Ifla ehgn xe khach 29 ehd (ky hieu xe K29) nlm khoang Iam doi tflpng nghien cflu Xe K29 cd ket eau khung gam xe khach cd lap ddng ca HYUNDAI County vdi cac yeu cau chinh sau; Gifl nguyen toan bd he thdng ddng eP va truyen dpng va cac cd c^u dieu khien eua d td sat xi gdm: Chassis, dpng ed, hop sd, cac dang, cau trfldc, cau sau, cac be thdng phanh, treo Iai Khdng lam anh hfldng den chat Ifldng, dp ben cua chassis Dam bao cac thdng so ve bfldc ghe, khoang each tfl sin den tran xe, chieu cao cfla xe, chieu rdng ghe khach theo quy dinh eua tieu chuan Viet Nam (TCVN) va cac tieu ehuan Nganh (TCN) cd lien quan Dam bao cac yeu cau ky thuat, my thuat va yeu eau sfl dung cua d td Phu hpp vdi yeu cau vat tfl vl cdng nghe dieu kien Viet Nam Khi thai cfla td dap flng mflc EURO III Vi?c bd tri ghe ngdi khoang hanh khach dflpc bd tri nhfl sau: Day ben trai gdm 05 hang ghe 02 chd ngoi va moi hang cd 01 ghe lat, 01 hing ghe 01 eho ngdi va 01 ghe lat va 01 ghe lai xe Day ben phai gom 05 hang ghe 01 ehd ngoi va 01 hang ghe 01 ehd ngdi va 01 ghe lat Day ghe cudi cung 04 chd ngdi Ghe ngdi khoang hanh khach dflpc bd tri vdi khoang trdng gifla hai hang ghe hen ke la 630mm Kich thflde ghe dam bao tieu chuan Nganh, cua d td khach Chieu rdng mat ghe cho 01 chd ngdi cua cac loai ghe dam bao tieu chuan 400x400 (mm), chieu cao tfl san d td den mat dem ngdi la 400mm, dam bao tieu chuan nganh ddi vdi xe khach Khung xfldng ghe dflpc che tao blng thep dng 027 Ghe ngdi dflpc bit chic chan vdi san d td blng cac bu ldng M10xl,25 va ghe dflpc lien ket vdi xe blng cac bu ldng M8xl,5 Hai ben dtd dflpc bd tri cac d cfla sd kieu kinh day, phia trfldc va sau dtd dflge Up kinh ed dinh Cac loai kinh sfl dung tren dtd deu ia kinh an toan Cfla len xudng hanh khach dflpc bd tri d than xe ben phai, loai ban le hai canh gap San d td dflpc tao bdi cac dam ngang chinh blng thep hinh L50x50x2 Cac dam ngang san dflpc lien ket chac ehan vdi dam ngang cua khung dtd blng bu long ban qua cac ke thep Khung xfldng san xe dflpc han tfl thep hinh U40x25x3, U50x30x3 He khung xfldng dflpc tao bdi cac cdt dflng blng thep hinh U76x40x3 Cac cgt ehinh dflpc gia cfldng de tang ben va cflng vflng bdi cae giang ngang blng thep L50x50x2, L40x40x2 va eae chdng gia cfldng L30x30x2 Mat ngoai eua khung xfldng dflpc bge blng tdn day 1mm, phia ed bpe ldp each nhiet va each am Than vd d td dflpc lien ket vdi cac dam ngang san blng phflpng phap han Old cd 01 cfla len xudng danh cho hanh khach bd tri phia ben phai than xe Cfla kieu hai canh gap nhfl cac d td khach cung loai Otd khach sfl dung loai Idp 7.00R16-12PR nhfl dtd sat xi X A Y D U > G MO HINH PTHH KHUNG VO XE 2.1 Phan tich cau true khung vo xe TAP C H l CO KHi V I £ T NAM V Sd (Thang nam 2013) NGHIEN CUTU - TRAO D | Khung vd xe la mgt ket cau phflc tap, chiu Ifle theo nhieu phfldng khdng gian, phu thudc vao hinh dang cua xe Tren khung vd xe dflpc gia cd nhieu ket cau tang cflng vflng va eae ket cau de giam tieng on Trong cdng nghe ehe tao d td, vd xe dflge cau tfl nhieu manh chi tiet blng cac phfldng phap dap va ban Phan tieh thed eau trflc, vd xe cua xe khach 29 cho bao gdm cd manh: Tam trfldc, tam sau, tam san, tam ndc, tam phai, tam trai Chieu day eua eae tam 0,9-1.0mm Cac manh dflge ghep vdi bang eae mdi han hoac bu long kep Ky thuat phan tich cau true khung vd xe khach da dflpc flng dung nganh cdng nghiep d td tren the gidi tfl rat sdm va den da dfldc phat trien manh nhd cd sfl tien bd eua may tinh dien tfl Ngoai flng dung ve thiet ke cdn dflpc flng dung de tinh toan cac flng suat khung vd xe va dflpc flng dung de tinh toan eac tai trgng udn, kha nang chju tai eua cac dam sat xi cfla xe Theo quan diem dp ben ta cd the md ta cau true vd xe khach theo mang tach rdi ddc lap nhau, hinh dflpc eac tan so dao ddng rieng va dang rieng cua vd xe (2) Tmh toan mflc dn khoang xe vd xe rung ddng Cac bfldc chinh xay dflng md hmh tinh toan theo thfl tfl sau: Bfldc 1: Phan tich cau true thflc eua vd xe, phan mang cau trflc Bflde 2: Xae dinh he tpa dp cho md hinh ^ Bfldc 3: Xay dflng md hinh hinh hpe cua vd xe va khoang ben xe Bfldc 4: Xae dinh eac thugc tinh vat lieu va thupc tinh phan tfl se sfl dung Bfldc 5: Chia Ifldi md hinh hinh hpe de nhan dflpc md hinh tinh toan (md hinh PTHH) Cac thdng sd cP ban eua xe khach 29 ch5 trinh bay tren hinh va bang a) Hinh ddng tong thexe Hinh Cdu true vo xe khdeh 29 chd phdn tich thdnh mdng 2.2 Xay dflng md hinh Phan tiif hflu han khung vd xe khach 29 cho Ngi dung tinh loan cua qua trinh dn rung bao gdm bai toan: (1) Phan tich modal: N h i m muc dich tim TAP CHi C O KHi VIET NAM •t* b) Bdn ve hinh chieu ddng xe Hinh Xe khdeh 29 cho Sd (Thang nam 2013) NGHIEN ClJfU - TRAO D | Bang 1: Thong sd ky thudt cua xe khdeh 29 chd Thong so Khoi lupng ban than (GJ -i-Phan bo len cau trfldc (G,,) -i-Phan bo len cau sau (G^,) Tai trpng cho phep, ke ca ngfldi lai (G_) Khoi lflpng toan bo (G) -Hphan bo len cau trfldc (G,) +Phan bo len cau sau (G,) Kich thflde bao (dai x rpng x cao) Chieu dai co sd (B) Vet banh trUdc(B,) Vet banh sau (B,) a) Xdc dinh he tga chung cda mo hinh: He tga chung cua vd xe can phai dflge xae dinh nham mue dieh tao lap ma tran ca ban cua toan bg ket cau vd xe va ghep ndi eac manh clu trflc eon Ph£n m^m Ansys cung cap nhieu he tga va dflpc sfl dung cho eae muc dieh khae nhfl: Don vi Kg Kg Kg Ngddi Kg Kg Kg mm mm mm mm Gia tri 2025 1180 845 29 6700 2600 4100 7060x1990x1600 3935 1190 1935 Md hinh PTHH ket cau than vd xe (structure model) dflpc xay dflng va trinh bay tren hinh vdi thdng sd nut va phan tfl: -So nut: 96156 nflt - Sd phan tfl: 47947 phan tfl + He tpa dp tdng the va dia phflong dflpc sfl dung eho cac vi tri hinh hpe (nut, diem ) Irong khdng gian + He tpa dp nflt dinh nghia bac tfl cho mdi nut va dinh hfldng cua dfl lieu ket qua nut + He tpa dp phan tfl de xac dinh sfl dinh hfldng cua thupc tinh vat lieu va dfl lieu ket qua phan tfl + H? tga dg ket qua dflpc sfl dung eho vi^c djch chuyen dfl lieu ket qua nut hoae phan tfl tdi mpt h^ thdng tpa dp rieng biet cho viee het ke, hien thi hoae xfl ly ket qua b) Xay dUng mo hinh PTHH khung vo xe Nhd vi?c sfl dung cdng nghe Scan3D nen vi^e dflng md hinh hinh hpe eho xe ed tinh ehuan xac cao so vdi xe mau, hinh Htnh Mo hinh hinh hoc xe khdeh 29 cho (Structure model) Sau da cd md hinh hinh hpe eua doi tflpng nghien cflu, tren cd sd md hinh ket cau vd xe Up ghep hoan ehinh, cac cfla ddng kin Md hinh la mdt khdi dflpc tao bdi be mat tiep xflc gifla vd xe va khdi khdng ben trong, ed ke den phan khdng gian bi chiem chd cfla ghe ngoi lai xe va hanh khach Do vay, md hinh khoang ben xe cung ed vi tri goc tpa dp tong the nhfl d md hinh ket eau Md hinh PTHH khdng khoang xe (airborn model) dfldc trinh bay tren hinh vdi cac thdng sd cua md hinh chia Ifldi: -Sd nut: 5710 - So phan tfl: 23830 phan tfl TA D riai r^rf ^Hf V I £ T NAM V Sd (Thang nam 2013) NGHIEN Cflu - TRAO D O I khach gay dn xe, thfldng t i p trung vao ba ngudn tae ddng chinh sau: • Tac ddng tfl dgng ca • Tac dgng tfl lop xe va mat dfldng • Tae ddng tfl khdng (khi ddng) a Tdc dgng dgng cd + Cac ngudn gay rung ddng tfl ddng ed: Hinh Mo Mnh khdi khong ben khoang xe (Airborn model) c) Xdc dinh cdc thugc tinh vat lieu vd thugc tinh phdn td Theo cac tai lieu ky thuat eua hang san xuat, cae dae tinh vat lieu cua khung vd xe la thep dap ed cae thdng so ky thuat trinh bay bang Bdng Thdng so ky thuat cua vdt lieu che tgo khung vo xe STT Thong sd Modun dan hoi He so Poat xong Khdi lupng rieng Ddn vi Mpa kg/m^ Gia tri thong so 20000 0.3 7800 Gan cac thudc tinh cho phan tfl cua md hinh bao gdm Ifla chgn kieu loai phan tfl va hang sd dac trflng cua chung Thude tinh phan tfl can dam bao dflpc trang thai flng suat gin vdi thflc te Trong thfl vien phan tfl cfla phan mem Ansys thi kieu phan tfl thich hpp cho eac tam cua vd xe la SHELL93; cac ldp vat lieu Idt phu hap thu am ed the dung phan tfl vd nut SHELL99; khung xe va eac tam dam ed the md ta bang phan tfl dam BEAM 2.3 Khao sat on rung khung vo xe khach 29 chd 2.3.1 Nguon rung vd tieng dn ciia to Trong qua trinh hoat ddng cua xe khach 29 chd cd nhieu nguon gay rung ddng tae ddng len khung vd xe khach va truyen len khoang hanh TAP CHi C O KHi VIET NAM - Dao ddng cua md men xoan qua trinh chay - Sfl mat can bang eua ddng cd - Do tinh chat xung eua qua trinh nap, thai cua ddng ed tao rung ddng + Cac nguon gay dn tfl ddng ed: - Tieng dn - Tieng dn - Tieng dn - Tieng dn - Tieng dn qua trinh chay co tfl ddng cp he thdng nap he thdng xa quat gid b Tdc dgng tii lop xe vd mat dUdng Khi xe hoat ddng, Idp xe va mat dfldng tflpng tie vdi gay on rung vdi eae nguyen nhan: - Sfl mat dong deu eua lop, mat dong deu ve dp cflng - Khi quay, ldp chiu mgt dao dgng thay ddi ed chu ky theo Ifle tae dung tfl mat dfldng Lflc gom phan: lflc hfldng kinh - lflc thing dflng tfl mat dfldng hfldng vao tam lop (song song vdi ban kinh Idp); lflc nam ngang - lflc tac dung song song vdi true banh xe; va lflc keo - Iflc nam ngang tac dung song song vdi hfldng chuyin dgng cua Idp - Tieng on hoa Idp tao tfldng tac gifla lop vdi mat dfldng Khi ldp lan tren mat dfldng, khdng bi kep cac ranh cua hoa lop va bi nen cac phan hoa ldp dd tiep xue vdi mat dfldng, khdng nen sau dd dflpc giai phdng khdi eac ranh tren mat Idp va gian nd tao tieng So (Thang nam Q i i L NGHIEN CUfU - TRAO OOl c Tdc dgng tii khong Cac phfldng trinh toan hpe sfl diing tinh toan: Day la tieng dn sinh tfldng tac gifla luong khdng vdi eac be mat ben ngoai eua vd xe di qua cae phan Idi ldm tren mat vd xe va sinh rdi phia sau ehung, bien thien ap suat cua roi lam rung vd xe va tao nen tilng dn Tieng dn dgng thfldng xay d vung tr^n vd xe; kinh trfldc, ndc xe, kinh sau va hai ben sfldn xe Trfldng hpp tilng dn gpi la tieng dn ddng Khi d td boat dgng se lien tue nhan dfldc kich thieh gay rung ddng tfl ddng ca, he thdng truyln lflc, ldp xe, mSp md mat dfldng, v.v Nhflng kich dgng truyen qua eac Hen ket khdp ndi, he thong treo din khung vd xe gay nen rung dgng va cac tai trgng udn, xoan va tai quan tinh Rung dgng cua vd xe den mflc dp nhat dinh (vl bien dp, tan sd) se phat tieng dn vao khoang ca bin (dfldng truyen ca - am hgc) ggi la dn rung Khi tan sd kich thich trung vdi tan sd rieng eua vd xe, bien rung ddng tang len bat thfldng lam cho mflc dp dn rung se tang cao Dieu rat de xay qua trinh van hanh cua d td vi khung vd d td la mdt cau true phflc tap gdm nhieu tam, ming cd nhieu tan sd rieng khae nhau, ddng thdi dli tSn sd cfla cac ngudn kich thieh lam rung vd xe rat r^ng Tilng dn rung cfla vd xe, vi the lien quan chat che vdi cau true cua vd va kich thieh rung ddng ma nd nhan dflpc 2.3.2 Dudng truyen tieng on vdo khoang xe Theo cae nghien cflu ve dn rung cua d td, tieng dn phia d td dflpc sinh bdi hai dfldng Iruyen, dd la: (1) Dfldi tac dung cua eae lflc kich thich thay doi theo thdi gian len khung va vd xe, lam rung ddng cac tam panel tao khoang ea bin Sfl rung ddng phat tieng on vao khdng gian ben Dfldng truyln tilng on la dfldng truyen cd - am hpe (2) Tieng on truyln trflc tiep tfl eac ngudn tieng dn qua cac Idp ngan vl vach ngan vao td, day la dfldng truyen khdng Phfldng trinh sdng am: d^p c^ St'' -y^p = o (1) Trong do: ffc^ c: tde dp eua am (c = ypo) Pg! Trpng Iflpng rieng eua chat Ichi k: Md dun khoi cua ehSt long p: Ap suat am t: Thdi gian Phflong trinh ddng Ifle hpe ket cau: [M.'^Uey[C^.'^Uy[KA{uJ-[RA{Pj={FAi2) Vdi [MJ : Ma tran khdi Iflpng kit cau [C ]: Ma tran dp cflng kit cau [KJ: Ma tran cin kit cau {u }: Vec tP gia tde nut {u }: Vec tP van tde nut {u}: Vec tP chuyen vi nflt {Fef: Vec tP tai tac dpng Blng phflong phap phan tfl hflu han sfl biln thien cua ap suat va chuyen vi dflpc xac dinh bang cdng thflc: P={N}T{Pe} (3) U={N'}T(ue} (4) Vdi: {N} La ham dang phan tfl ap suat {N'} la ham dang eua ehuyen vi {Pe}: Vec to ap suat nflt {ue}={uxe},{uye},{uze} Vec td phan tfl chuyin vi nut Gradients ap suat theo phfldng x, y, z dflpc tinh toan tai tam phan tfl sfl dung tinh toan gia tri ap suat nflt: 9P/3x={3N/3x|T{Pj (5) ap/ay={aN/ay}T { p j ap/az={aN/az(TiPj (6) (7) Mflc ap sual am dfldc tinh toan bdi: 2.3.3 Cd sd ly thuyet truyen dm L ^=20 log [\P^^^ • ' -^O KHf V I £ T NAM • Sd (Thang nam 2013) (S)'^ NGHIEN Cflu - TRAO DOI MOT SO KET QUA 3.1 Kit qud khdo sdt mo hinh PTHH kit cdu thdn vo xe Mo hinh da tinh toan diioc cdc dang rieng dao dong khac nhau, moi dang rieng co mot tan so dao dong khac nhau, hinh Cac gia tri tan so ciing dilgc trinh bay cu the dang bang so, bang f^ ^ I" a) Ket qud dang neng tai /= 47,668 ^ b) Kit qud dgng neng tgi f=47,668Hz Hinh Mot s6 ket qud mo phong mo hinh PTHH ket cdu thdn vo xe Bdng Gid tri cua 10 dang rieng thdn vo xe khdeh 29 chd TliiJtil Tan so 31,126 39,876 46,143 47,668 51,941 ThlJtll 10 Tan so 56,694 62,743 64,792 69,218 70,593 3.2 Ket qua khao sat mo hinh PTHH kh6i khdng khoang xe Mo hinh da cho ket qua cac vi tri khac khoang xe, bang Cac gia tri ap suat am dflpc bieu thi bang hai thfl nguyen (N/mm^) hoac mflc ap suat am theo (dB), hoac dang md hinh co bieu thj mau tfldng flng tai cac vi tri khac khoang xe de ta cd the nhin trflc quan hdn, hinh Bdng Mot s6 kit qud tinh todn dp sudt vd mde dp sudt dm tgi cdc vi tri khoang xe khdeh 29 chd STT Phan tLi so Ap suat am (N/mm^) Miic ap suat am (dB) 23806 -0 61567E-01 66.756 23807 -0.66708E-01 67453 23808 -0.64160E-01 67.114 10 23815 -0.57772E-01 66.203 U 23816 -0.41057E-01 63.237 12 23817 -0.33750E'01 61.534 20 23825 -0.71394E-01 68,042 20 23825 -071394E-01 68.042 21 23826 -0.74965E-01 68.466 24 23829 -0.73177E-01 68.257 25 23830 -0.72677E-01 68.197 ail TAP c m CO KHi VIET NAM V S6 (Thang nam 2013) NGHIEN Cflu - TRAO 06l AN '"s \ \L, , , — , ; • ; : ' , a) Dgng kit qud mde dp sudt dm thti nhat b) Dgng ket qud mUc dp sudt dm thd hai khoang xe khoang xe Hinh Mot so ket qud mo phong mo hinh PTHH khoi khong khoang xe KET LUAN Kit qua nghien cflu da xay dflng dfloc md hinh PTHH cau true than vd xe (strcture model) va md hinh PTHH khdi khdng khoang xe (airborn model) de khio sal dn rung khung vd xe khach 29 eho nhd sfl dung ky thuat Scan3D va ket ndi vdi phan m i m Ansys da cho ta kel qua tinh nhanh hdn, tilt kiem thdi gian va kit qua chinh xac hdn Viec cap nhat eae dfl lieu dau vao trflc tilp va cd the tong hgp dflpc cac ngudn gay rung dn lai vdi Cung blng ky thuat ed the md rdng xay dflng md hinh PTHH vdi nhflng xe cd ket cau phflc tap hon nhfl khung vd d td tai hoac d td vl cung cd t h l flng dung de khao sat cae trfldng hpp khung vd ed vat lieu khac • Ngay nh^n bai: 01/02/2013 Ngay phin biln: 20/3/2013 Ngfldi phan bien: TS DflOng Ngoc Khanh, Bd mdn O td, Trfldng Dai hoc Bach khoa Ha Ndi Tiki lieu tham khao: [1] John Fenton, (1996), Handbook of Vehicle design analysis, SAE Warrendale, pa., USA [21 Heinz Heisler, (1989), Advanced Vehicle Technology, First published in the United Kingdom [3] J.R Elliis, (1994), Vehicle Handling Dynamics, Mechanical Engineering Publications Limited - London, First published 14] Pedro REIS and Que VU DO, (2006), Noise Vibration Harshness (NVH) Simulation in Engine Mass Balancer System, SAE [51 Kazuhiro, Miy AGL Tokiyoshi, YANAI, (1987), Evaluation Method of Noise and Vibration on Drive Train System, Japan 16] Nguyen Hflu Can, Dfl Quoc Thinh, Pham Minh Thai, Nguyen Van Tai, Le Thj Vang, (1998), Ly thuyet to mdy keo, NXB Khoa hoc va Ky thuat, Ha Npi [7] Nguyen Van Khang, (2004) Dao ddngky thudt NXB Khoa hoc Ky thuat Ha Npi TA P CHf CO KHf V I £ T NAM Sd (Thang nam 201 >} ... SHELL99; khung xe va eac tam dam ed the md ta bang phan tfl dam BEAM 2.3 Khao sat on rung khung vo xe khach 29 chd 2.3.1 Nguon rung vd tieng dn ciia to Trong qua trinh hoat ddng cua xe khach 29 chd... xe khach 29 ch5 trinh bay tren hinh va bang a) Hinh ddng tong thexe Hinh Cdu true vo xe khdeh 29 chd phdn tich thdnh mdng 2.2 Xay dflng md hinh Phan tiif hflu han khung vd xe khach 29 cho Ngi... dtd sat xi X A Y D U > G MO HINH PTHH KHUNG VO XE 2.1 Phan tich cau true khung vo xe TAP C H l CO KHi V I £ T NAM V Sd (Thang nam 2013) NGHIEN CUTU - TRAO D | Khung vd xe la mgt ket cau phflc tap,
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