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DESIGN, ANALYSIS ANALYSIS AND OPTIMIZATION OPT IMIZATION OF CRANE HOOK MODEL DIN 15401 ABSTRACT
Crane hook are highly liable component and are always subjected to failure due to accumulation of large amount of stress which can eventually lead to its failure. In this paper the design of the hook is done by analytical method and design is done for the different different materials materials like forged steel and high tensile steel. After the analytical method design and modeling of hook is done in modeling soft-ware (pro-E .!he modeling is done using the design calculation from the modeling the analysis of hook is done in "EA software (A#$%$.!his result lead us to the determination of stress in e&isting model. 'y predicting the stress concentration concentration area the hook working life increase and re-duce the failure stress. !o study the stress pattern of crane hook in its loaded condition a solid model of crane hook is prepared with the help of )*+-E software In this present work to study the different different design parameter parameter , stress pattern of crane hook in its loaded condition for different cross section the design and drafting of crane hook will be prepared by using A#$%$ ./. 'y finite element analysis the stress whic whichh is to be form formed ed in vari variou ouss cros crosss sect sectio ionn are are com compare paredd with with desi design gn calculation. !he stress concentration factors are used in strength and durability evaluation of structure and machine element. In this work and also we observe the parameter that affects the weight reduction. !o minimi0e minimi0e the failure of crane hook the stress induced in it must be studied. A crane is subjected to continuous loading and unloading. !his may causes fatigue failure of the crane hook but the load cycle fre1uency is very low. If a crack is developed in the crane hook mainly at stress concentration areas it can cause fracture of the hook and lead to serious accidents. In ductile fracture the crack propagates cont contin inuo uous usly ly and and is more more easi easily ly dete detect ctab able le and and henc hencee pref prefer erre redd over over brit brittl tlee fracture. In brittle fracture there is sudden propagation of the crack and the hook fails suddenly. 1
Crane hooks are the components which are generally used to elevate the heavy load in industries and constructional sites. *ecently e&cavators having a crane ‐ hook are widely used in construction works site. CHAPTER 1 STUDY ABOUT ABOUT CRANE HOOK 1.1 INTODUCTION
Crane hooks are the components which are generally used to lift the heavy load in industries and constructional work. *ecently e&cavators having a crane-hook are widely used in construction works site. +ne reason is that such an e&cavator is convenient since they can perform the conventional digging tasks as well as the suspension works. Another reason is that there are work sites where the crane trucks for suspension work are not available because of the narrowness of the site. In general an e&cavator has superior maneuverability than a crane truck. 2ery few people have already worked on the optimi0ation of crane hook. 3enerally material type and cross section area and radius are design parameter that affects the weight of crane hook. Cast iron structural steel is generally used as manufacturing material for crane hook. !he behavior of mechanical properties of different different steel grades at elevated temperatures should be well known to understand the behavior of steel and composite structures at fire. 4uite commonly simplified material models are used to estimate e.g. the structural fire resistance of steel structures. In more advanced methods for e&le in finite element or finite strip analyses it is important to use accurate material data to obtain reliable results. 1.2 PRINCIPLE OF HOOKS
Crane hook is very significant component used for lifting the load with the help of chain or wire ropes. Crane hooks are highly liable components and are always subjected to bending stresses which leads to the failure of crane hook. !o minimi0e the failure of crane hook the stress induced in it must be studied. A crane is subjected to continuous loading and unloading. !his may causes structural failure of the crane hook. In the present work an attempt has been made by considering four different types of cross sections of crane hooks and are designed theoretically by using curved beam concept. CA!IA software is used for 2
modeling the crane hook and A#$%$ software used to find out the stresses. As a conclusion the results obtained from A#$%$ and theoretical calculations are compared. 1.3 FAILURE OF CRANE HOOKS
!o minimi0e the failure of crane hook the stress induced in it must be studied. A crane is subjected to continuous loading and unloading. !his may causes fatigue failure of the crane hook but the load cycle fre1uency is very low. If a crack is developed in the crane hook mainly at stress concentration areas it can cause fracture of the hook and lead to serious accidents. In ductile fracture the crack propagates continuously and is more easily detectable and hence preferred over brittle fracture. In brittle fracture there is sudden propagation of the crack and the hook fails suddenly. !his type of fracture is very dangerous as it is difficult to detect detect.. $trai $trainn aging aging embrit embrittle tleme ment nt due to contin continuou uouss loadin loadingg and unload unloading ing change changess the micros microstru tructu cture. re. 'endin 'endingg stress stresses es combin combined ed with with tensil tensilee stress stresses es weakening of hook due to wear plastic deformation due to overloading and e&ce e&cess ssiv ivee ther therma mall stre stress sses es are are some some of the the othe otherr reas reason onss for for fail failur ure. e. 5enc 5encee continuous use of crane hooks may increase the magnitude of these stresses and ultimately result in failure of the hook. All the above mentioned failures may be prevented if the stress.
1.4 MARKING •
•
!he manufacturer6s identification shall be forged cast or die-stamped on a low-stress and non-wearing area of the hook. 5oisting hooks furnished by the original hoisting e1uipment manufacturer manufacturer as an integral part the hoist assembly or by the original hoist manufacturer as replacement hooks are not re1uired to have manufacturer markings. markings. 1.5 ATTACHMENTS
5oisting hooks shall be fitted with a latch to bridge the throat opening to prevent the accidental release of slings or attachments. 5ooks without latches may be used in special applications where the latch would interfere with the proper use of the hook providing that the use of the hook is restricted to the application for which it 3
is appr approv oved ed and and in 1ues 1uesti tion onab able le case cases s conc concur urre renc ncee is obta obtain ined ed from from the the appropriate safety organi0ation. If a handle or latch support is re1uired to be welded to the hook welding shall be done prior to final heat-treating. 1.6 LOAD LIMITS
5ooks shall not be loaded beyond rated capacity e&cept during load tests of the e1uipment of which they are a part. 1. HOOK STANDARDS
5ook design shall meet generally accepted hook design standards and be
compatible with the re1uirements of A$7E '89.9. 5ook material shall have sufficient ductility to permanently deform before
failure at the ambient temperatures at which the hook will be used. :hen a latch is provided it shall be designed to retain such items as slings
under slack conditions. !he latch is not intended to support the load. !he bearing surfaces of new hooks shall be the arc of a circle. 3auge points
or hook gauges for measuring spread after load testing should be provided. "ield-fabricated hooks shall meet the re1uirements of this section and shall
be approved by a 1ualified 1ualified engineer. engineer. 1.! TESTING
Each Each new new or repl replac acem emen entt hook hook of /9/9-to tonn capa capaci city ty or grea greate terr and and a
prototype of each hook design of less than /9-ton capacity shall be prooftested by the manufacturer in accordance with !able 8-. :hen proo prooff test testss are are used used the the hook hookss shal shalll with withst stan andd the the proo prooff load load :hen application without permanent deformation when the load is applied for a mini minimu mum m of / seco second nds. s. !h !his is cond condit itio ionn is cons consid ider ered ed sati satisf sfie iedd if the the permanent increase in the throat throat opening does not e&ceed 9./ percent percent or 9.9 in. (9.;/ mm whichever is greater. "or a duple& (sister hook having a pin eye the proof load for the eye shall 4
be in accordance with !able !able 8-. !he proof load shall be shared e1ually between the two prongs of a sister hook unless the hook is designed for unbalanced loading. 5ooks that have been proof-tested may be subse1uently inspected by the magnet magnetic ic partic particle le method method in accord accordanc ancee with with A$!7 A$!7 E-<9= E-<9= (>$tan (>$tandar dardd )ractice for 7agnetic )artic )article le E&ami E&aminat nation ion? ? and shall shall show show no cracks cracks inclus inclusion ions s or other other relevant discrepancies@ casting shall be evaluated in accordance with A$!7 E-/ (>$tandard )ractice for Bi1uid )enetrate Inspection 7ethod?. )erformance testing of hooks shall not be re1uired e&cept where necessary
to conform to the re1uirements for the e1uipment of which they are part. :hen testing is specified documentation shall be uni1uely identified to the hook by serial number or other identifier.
If detailed inspections are performed (refer to sections 8.;.8.b 8.;..c and 8.;./.b. the results shall be evaluated by a 1ualified person to determine the need for subse1uent #!. If #! is deemed necessary it shall be performed in accordance with $ection $ection 8..8. 1.". 1.".2 2 NDT NDT REC RECOR ORDS DS
ated and signed #! records traceable to the hook by a serial number or other identifier shall be kept on file as long as the hook remains in service and shall be readily available to appointed personnel. 1.". 1.".3 3 NDT NDT MET METHO HODS DS
Dse magnetic-particle testing or li1uid penetrate testing methods to inspect for surface intersecting discontinuities. A 1ual 1ualif ifie iedd insp inspec ecto torr or desi design gnat ated ed pers person on shal shalll perf perfor orm m #! #!s in accordance with the following A$!7 A$!7 standards (a A$!7 E-<9=. E-<9=. (bA$!7 (b A$!7 E-/. E-/. "or magnetic-particle testing a coil yoke or wet techni1ue should be used to eliminate the possibility of prod burns or arc strikes. 5
)erform an #! with the hook in place unless conditions indicate that disassembly for thread or shank inspection is necessary. 1.".4 1.".4 ACCEP ACCEPT TANCE CRITER CRITERIA IA
A designated person shall document and resolve the following relevant indications Arc strikes (welding or electrical. $urface intersecting discontinuities 9.;/ in. long or longer. • •
1.".5 DISCONTIN DISCONTINUITY UITY REMO# REMO#AL
i !wo !wo directions directions of discontinui discontinuity ty >)? and >!? >!? iscontinuit iscontinuityy >)? parallels parallels the contour of the hook is considered no serious and does not re1uire removal. iscontinuity >!? on the other hand is transverse to the contour contour of the hook and is more serious@ when occurring occurring in 0ones 0ones ' C or discontinuity ii >!? may may reduce the the longevity longevity of of the hook. hook. iiiiscontinuities may be removed by grinding longitudinally following the contour of the hook to produce a smooth gently undulating surface. In 0one 0oness ' and and such such grin grindi ding ng shal shalll not not redu reduce ce the the orig origin inal al hook hook dimension by more than 9 percent. $uch a reduction will not affect the working load limit rating or the ultimate load rating of the hook. In 0one C grinding shall not reduce the original dimension by more than / percent. iv Dnder Dnder norma normall and proper proper applic applicati ation on 0one 0one A is an unstre unstresse ssedd 0one. 0one. !herefore it is not re1uired that discontinuities in that 0one be ground out. v !he hook shall shall be ree&amined ree&amined by performi performing ng an #! after after grinding grinding to verify removal of relevant discontinuities.
1.10 MAINTENANCE
a. A hook latch that is inoperative or missing shall be repaired or replaced. 6
b. A hook with a latch that does not bridge the throat opening shall be removed from service until the latch is replaced or repaired and the hook is e&amined for deformation with special attention to the throat opening. c. A desi design gnat ated ed pers person on shal shalll repa repair ir crac cracks ks nick nicks s and and goug gouges es by grin grindi ding ng longit longitudi udinal nally ly follow following ing the contou contourr of the hook hook provid provided ed no dimens dimension ion is reduced more than 9 percent (or as recommended by the manufacturer of its original value. d. All other repairs shall be performed by the manufacturer or a 1ualified person. e. *eplacement parts such as load pins for clevis hooks shall be at least e1ual to the original manufacturer6s specifications. specifications. 1.11 OPERATION
5ook users shall do the following etermine that the weight of the load to be lifted does not e&ceed the load
rating f the hook. Avoid shock loading. Center the load in the base (bowl or saddle of the hook to prevent point
loading of the hook. o not use hooks in such a manner as to place a side- or backload on the
hook. :hen using a device to bridge the throat opening of the hook ensure that no
portion of the load is carried by the the bridging device. device. Feep hands and fingers from between the hook and the load. Bo Boad ad dupl duple& e& (sis (siste ter r hook hookss e1ua e1uall llyy on both both side sides s unle unless ss the the hook hook is
specifically designed for single loading. o not load the pinhole in duple& (sister hooks beyond the rated load of the
hook. 7
CHAPTER 2 TYPES OF HOOKS 2.1POINT 2.1 POINT HOOKS $SINGLE $SINGLE HOOKS% DIN 15401
It is a single hook design which is forged from high 1uality steel and is used specifically with suspended loads. It supplies a wide range of )oint 5ooks up to 9./ !on !on in weight. $afety catches can be supplied as an optional e&tra and the shank length can be forged to your individual specification.
Figure 1
2.2 SHANK LIFTING HOOKS
!he Crosby $8= 5oist $hank 5ooks from /99kg to
throat opening has changed thus indicating abuse or overload.
Figure 2
2.3RAMSHORN HOOKS
!he twin hook design makes it ideal for use with two webbing slings - this design assists greatly with load distribution prevents any lifting sling damage and avoids choking at the hook. *am-shorn 5ooks are commonly used with heavy lifting cranes and are found e&tensively in container and shipping ports.
Figure 3
2.4 CLE#IS LIFTING HOOKS
A clevis hooks is a hook consisting of a clevis clevis pin and tang. !he clevis is a D-shaped piece that has holes at the end of the prongs to accept the clevis pin. !he clevis pin is similar to a bolt but is only partially threaded or unthreaded with a cross-hole for a split pin. !he tang is a piece that fits in the space within the clevis and is held in place by the clevis pin. !he combination of a simple clevis fitted with a pin is commonly called a shackle although a clevis and pin is only one of the many forms a shackle may take.
9
Figure 4
2.5EYE LIFTING HOOKS
Eye lifting hooks at 3rainger to help lift load unload and transport heavy items on the loading dock in the warehouse in the yard and more. Choose from various si0es and fork spreads in single and double fork single and double swivel hook styles and more. "ind the forklift truck lifting hooks that can fit your application at 3rainger.
Figure 5
10
2.6S'I#ELS HOOK
"ollowing a tendency to unwind itself a wire rope line when e&tended will cause its load to rotate. !hus there is a need for some form of intermediate fitting which will allow the rope to take its natural course without affecting the load.
*ope block has a wide range of blocks and related lifting products such as swivels overhaul balls and lifting beams. +ur line of standard- and fast reeve blocks are preferred by many +E7 crane manufacturers manufacturers as well as crane end-users. 'esides these standard lines of blocks our Custom swivels and hook blocks suitable for offshore marine and subsea use are renowned for their 1uality safety and durability. 3.2 S)*+*- R/ B
*ange from G H ;/9 ton. 5igh tensile side plates Compact and multipurpose design. $winging hook suspension for swiveling hook. 3.3F*) R/ B
*ange from G H ;/9 ton. "ast reeving without removing the socket from the wire rope. rope. 5igh 5igh tensil tensilee side side plates plates with with integ integrat rated ed handgr handgrips ips for for positi positioni oning ng and
11
stabili0ing before catching load. Compact and multipurpose design. $winging hook suspension for swiveling hook. 3.4 S/ 7 O/-8*9 B*
*ange from ; H G9 ton. 'ody in forged steel with 'ecket on top for easy fitting of an open wedge socket or shackle. 5ook in forged alloy steel with safety latch first class thrust bearing including grease fitting. 3.5 S+*)8 B
*ange from ; H ;/9 ton. 5eavy duty block with a compact design. 5igh tensile side plates. $winging suspension for swiveling top connection. 3.6 S8*/ S8*/
Available in many different types of material such as nylon and steel and can be cast welded and forged. +ther parameters such as groove angle and hardening are all engineered to meet your specific re1uirements. Dsed in our full line of craneand and hook hook bloc blocks ks.. Conc Concen entr trat atio ionn area areass are are well well pred predic icte tedd and and som some desi design gn modification to reduce the stresses in these areas.
Figure 1
12
Figure 2
METHODOLOGY ADOPTED
A virtua virtuall model of I# / 9 lifting lifting hook similar similar to actual sample sample is created using pro-e software and then model was imported to A#$%$ software for "inite element stress analysis and the result of stress analysis are cross checked with that of :inkler-'ach formula for curved beams. CHAPTER 4 PRO:E7CREO SOFT'ARE SOFT'ARE 4.1 PREPA PRE PARAT RATION ION OF CAD MODEL OF HOOK
"or generation of CA model of crane hook various geometrical features and dimensions are selected. $ome features are appro&imated for simplification. )ro-E :ildfire /.9 software is used for creating solid model of hook. $wept 'end advance feature in )ro-E is used. Complete $olid CA model is prepared and it is saved in .igs format. $imilarly for all re1uired cross section solid CA model is generated. )!C Creo formerly formerly known known as )roE#3I#EE* is a parametric integrated 8 CACA7CAE solution created 13
by )arametric !echnology echnology Corporation ()!C. It was the first to market with parametric feature-based associative solid modeling software. !he application runs on 7icrosoft :indows platform and provides solid modeling assembly modeling and drafting finite element analysis direct and parametric modeling subsub-di divi visi sion onal al and and nurb nurbss surf surfac acin ing g and and #C and and tool toolin ingg func functi tion onal alit ityy for for mechanical engineers. It features a suite of 9 applications which work within the same program. 2ersions for D#IJ systems were discontinued after the release of version .9 e&cept $olaris on &G-. !he )roE#3I#EE* name was changed to Creo Elements)ro also known as :ildfire :ildfire /.9 on +ctober ;G ;99 coinciding with )!C6s announcement of Creo a new design software application suite. Creo Elements)ro will be discontinued after version ; in favour of the Creo design suite. Creo Elements)ro and now Creo )arametric compete in the market with )*+-E and and $iem $iemen enss #J. #J. Creo Creo Elem Elemen ents ts) )ro ro (for (form merly erly )ro )roE# E#3I 3I# #EE EE* * )! )!CK CKss parametric integrated 8 CACA7CAE solution is used by discrete manufacturers for mechanical engineering design and manufacturing. manufacturing. )roE#3I#EE* was the industryKs first rule-based constraint (sometimes called LparametricL or LvariationalL 8 CA modeling system. !he parametric modeling approa approach ch uses uses param paramete eters rs dimens dimension ions s featur features es and relati relations onship hipss to captur capturee intended product behavior and create a recipe which enables design automation and the optimi0ation of design and product development processes. !his design appr approa oach ch is used used by com compani panies es whos whosee prod produc uctt stra strate tegy gy is fami family ly-b -bas ased ed or platform-driven platform-driven where a prescriptive design strategy is fundamental to the success of the design process by embedding engineering constraints and relationships to 1uickly optimi0e the design or where the resulting geometry may be comple& or based upon e1uations. Creo Elements)ro provides a complete set of design analysis and manufacturing capabilities on one integral scalable platform. !hese re1u re1uir ired ed capa capabi bili liti ties es incl includ udee $oli $olidd 7o 7ode deli ling ng $urf $urfac acin ing g *end *ender erin ing g ata ata Interoperability *outed $ystems esign $imulation !olerance Analysis and #C and !ooling esign. Creo Creo Elem Elemen ents ts) )ro ro can can be used used to crea create te a com complet pletee 8 digi digita tall mode modell of 14
manufactured goods. !he models consist of ; and 8 solid model data which can also be used downstream in finite element analysis rapid prototyping tooling design and C#C manufacturing. All data are associative and interchangeable between the CA CAE and CA7 modules without conversion. A product and its entire bill of materials ('+7 can be modeled accurately with fully associative engi engine neer erin ingg draw drawin ings gs and and revi revisi sion on cont contro roll info inform rmat atio ion. n. !h !hee asso associ ciat ativ ivel elyy functionality in Creo Elements)ro enables users to make changes in the design at any time time during during the produc productt develo developm pment ent proces processs and automa automatic ticall allyy update update downstream deliverables. !his capability enables concurrent engineering H design analys analysis is and manuf manufact acturi uring ng engine engineers ers worki working ng in parall parallel el H and stream streamlin lines es product development development processes.
15
4.2 CIRCULAR CROSS:SECTION CRANE HOOK CREATED BY PRO:E
Figure 1
4.3TRA 4.3TRAPEZ PEZOID OIDAL AL CROSS CROSS:SE :SECTI CTION ON CRANE CRANE HO HOOK OK CREA CREATE TED D BY PRO:E
16
Figure 2
CHAPTER 5 ANSYS FINITE ELEMENT METHOD
!he finite element method is used to solve partial differential e1uations numeri numerical cally ly.. Almost lmost all physic physical al phenom phenomena ena are are model modeled ed using using diffe differen rentia tiall e1uations and in most cases the e1uations are too complicated to be solved by classical analytical methods. !he approach of the finite element method is to divide the region of interest into smaller elements finite elements. Instead of seeking an appro&imation appro&imation that holds for the entire region appro&imation that holds for a small part of the region is used. !he smaller parts are connected by their boundaries which makes it possible to build up a global e1uation system describing the physical behavior of the entire region. It is a characteristic behavior of the finite element method that as the number of finite elements used to describe a problem is increased the error of the appro&imation decreases. !he finite element method can be used to solve differential differential e1uations describing ground water flow electrical current laminar flow in pipes and many other physical engineering problems.
17
!his section e&presses "E analysis process. 'lock diagram of a typical finite element computer program. 'efore entering the program6s program6s preprocessor preprocessor the user should have planned the model and gathered necessary data. In the preprocessor block the user defines the model through the comm comman ands ds avai availa labl blee in the the prep prepro roce cesso ssorr. !h !hee defi defini niti tion on incl includ udes es inpu inputt and and generation of all node point.
Figure 1
A#$%$ is a finite element- based tool that provides a powerful design and analysis software package. A#$%$ 7echanical software is a comprehensive "EA analysis (finite element tool for structural analysis including linear nonlinear nonlinear and dynamic studies. !he engineering simulation product provides a complete set of elements behavior material models and e1uation solvers for a wide range of mechanical design problems. In addition A#$%$ 7echanical offers thermal analysis and coupled-physics capabilities involving acoustic pie0oelectric thermalHstructural and thermo-electric analysis. It is regarded by many researchers and engineers as a 18
modern modern accura accurate te robust robust and visual visually ly sensib sensible le tool tool to provi provide de soluti solutions ons for numerous engineering and scientific problems. 5.1 MESH ME SH GENERATIN BY ANSYS ANSYS
Figure 2
5.2 'HAT IS #ON MISES STRESS
2on 7ises stress is widely used by designers to check whether their design will withstand a given load condition. M NM; H (M M; O
σ y
2
FS
:here M Pma& stress M; Pmin stress 19
My P yield stress "$P "actor of safety 5.3 USE OF #ON MISES STRESS
2on 7ises stress is considered to be a safe haven for design engineers. Dsing this information an engineer can say his design will fail if the ma&imum value of 2on 7ises stress induced in the material is more than strength of the material. It works well for most cases especially when the material is ductile in nature. +ne of the most easy way to check when a material fails is a simple tension test . 5ere the material is pulled from both ends. :hen the material reaches the yield point (for ductile material the material can be considered as failed. an actual engineering problem with a comple& loading condition. Can we say here also that the material fails when the ma&imum normal stress value induced in the material is more than the yield point value . If you use such an assumption you would be using a failure theory called Knormal stress theoryK. 7any years of engineering e&perience has shown that normal stress theory doesn6t work in most of the cases. !he most preferred failure theory used in industry is Q2on 7ises stress6 based. :e will e&plore what 2on 7ises stress is in the coming section. 5.4 INDUSTRIAL APPLICATION OF #ON MISES STRESS
istortion energy theory is the most preferred failure theory used in industry. It is clear from above discussions that whenever an engineer resorts to distortion energy theory he can use 2on 7ises stress as a failure criterion 5.5 DISTORTION ENERGY THEORY
!he concept of 2on mises stress arises from the distortion energy failure theory . istortion energy failure theory is comparison between ; kinds of energies istortion energy energy in the actual case ; istortion energy in a simple tension case at the time of failure. According to this theory failure occurs when the distortion energy in actual case is more than the distortion energy in a simple tension case at the time of failure. +ne can note that 2on 7ises stress is at ma&imum towards the fi&ed end of the beam. !his is less than the yield point value of mild steel. $o the design is safe. In short an engineerKs duty is to keep the ma&imum value of 2o 2on 7ises stress induced in the material less than its strength. 20
5.6 BENEFITS OF THE DETERMINISTIC ANALYSIS
HDsing the deterministic analysis we have been able to investigate the performance of the design over continuous ranges of the input parameters using a limited number of simulations. H "rom the response surface we are able to identify the key parameters really influencing the design. HAlso we have been able to identify several candidates for the final design. Dsing engineering practice helps then to choose the final one. H!he deterministic approach helps identify the performance that can be reached with the actual esign (!rade +ff plots 5. FI;ED SUPPORT APPLIED
21
Figure 2
5.! FORCE 12KN APPLIED IN DO'N'ARD DIRECTION
22
Figure 3
5." ST STRE RES SS COMP OMPARISO ISON TRAPIZODAL HOOK
BET' BE T'EE EEN N
Figure 4
CIRC IRCULAR LAR
HOOK AND
Figure 5
5.10 STRESS COMPARISON COMPARISON BET'EEN DIFFERENT MATERIALS MATERIALS OF HOOK
23
"orged steel
structural steel
wrought iron
5.11 STRAIN COMPARISON BET'EEN DIFFERENT MATERIALS OF HOOK
"orged steel
structural steel
wrought iron
5.12 DEFORMATION DEFORMATION COMPARISON B7' DIFFERENT MATERIALS MATERIALS OF HOOK
;oun(Os un(Os &odu &odulu lus s &Pa &Pa Pois Poisso sonOs nOs Rati Ratio o
37
ul ul &odul &odulus us &Pa &Pa
S'ea S'earr &odu &odulu lus s &Pa &Pa
2.1e>005
0.C0C
1.::**e>005
9059C
CHAPTER .1 ANALYTICAL METHOD FOR STRESS CALCULATION
Curved beam fle&ure formula is used when the curvature of the member is pronounced as in case case of hook for different different cross cross sections mathematical mathematical analysis of stress.
F M × y σ = + A I
:here 7Pma&imum bending moment. %Pistance between centroidal a&is to neutral a&is. APArea of the cross-section 38
IP7oment of inertia for different different cross sections taken from design data book "or a triangular cross section@ Area of a triangleP
b× h 2
3
7oment of inertia (I P %P
F M × y σ = + A I
$tress
imension calculated by analytical method@ bPG9mm bP8mm hP99mm )P;9F#
'ending moment (7 P -;9R98R9.P-;999#m irect stress (
σ d
P A
P
3
P
120 × 10
−3
5.8 × 10
R9- P ;9.G7#m;
'ending $tress at A (M b A P
M AR
2
R 2 H
(N
D 2
R R + D 2
2
0.057
0.1
P (N 'ending stress at ' (Mb' P
−3
3.91 × 10
R
0.1+ 0.057
P-8=.<97#m; M AR
R
D 1
2
(- H 2 R R − D1 40
0.1 + 0.057 0.1− 0.057
)
¿
P
−12000 −3
5.8 × 10
× 0.1
2
0.1
¿ -
−3
3.91 × 10
×
0.043 0.1−0.043
P -;9.G(-.=; P=.9;7#m; MA P Md N(' bA
P;9.GN(-8=.<9
P-=.9;7#m;
M 'dN(' b'
P;9.GN=.9; ;
P8=.<7#m
.2 HOOK DESIGN BY ANALYTICAL METHOD
!he various dimensions for crane hook are taken as follows 'ed iameter
a1= x √ p
P ;
√ 120
P 8./mm V 89mm (appro&
:here ) P load F#mm ; JPconstant ranging between ; to ; for economic design & should be as minimum as possible. ; !hroat of 5ook ( a2@
a2 P 9.
P9.
V99mm
8 epth of cross-section Area Area ( h1@ h1 P 9W p N
a1 10 130
P9W;9 N :here
10
P;9./mm V;9mm )PBoad F#mm; aP'ed diameter mm
:idth of cross-section (b @ b P 9./h P 9./R;9P
42
43
CHAPTER ! HOOK
$teels are alloys of iron and carbon widely used in construction and other appl applic icat atio ions ns beca becaus usee of thei theirr high high tens tensil ilee stre streng ngth thss and and low low cost costs. s. Carb Carbon on According to the :orld $teel Association there are over 8/99 different grades of steel encompassing uni1ue physical chemical and environmental properties. In essence steel is composed of iron and carbon although it is the amount of carbon as well as the level of impurities and additional alloying elements that determines the properties of each steel grade. !he carbon content in steel can range from 9.-./X but the most widely used grades of steel contain only 9.-9.;/X carbon. Elements such as manganese phosphorus and sulphur are found in all grades of steel but whereas manganese provides beneficial effects phosphorus and sulphur are deleterious to steelKs strength and durability. ifferent types of steel are produced according to the properties re1uired for their application and various grading systems are used to distinguish steels based on these properties. According to the American Iron and $teel Institute (AI$I steels can be broadly categori0ed into four groups based on their chemical compositions . ;. 8. .
Carb Carbon on $tee $teels ls Allo Alloyy $tee $teels ls $tai $tainl nles esss $tee $teels ls !ool $tee $teels ls
!.1 CARBON STEELS
Carbon steels contain trace amounts of alloying elements and account for =9X of total steel production. Carbon steels can be further categori0ed into three groups depending on their carbon content Bow Carbon $teels7ild $teels contain up to 9.8X carbon 7edium Carbon $teels contain 9.8 H 9.X carbon 5igh Carbon $teels contain more than 9.X carbon
44
T=> ? )
P-+)*@ ? *-+
7ild steel
Dp to 9.;/X
7edium carbon steel
9.;/X to 9./X
5igh carbon steel
9./X to ./9X
!.2 ALLOY STEELS
Alloy steels contain alloying elements (e.g. manganese silicon nickel titanium copper chromium and aluminum in varying proportions in order to manipulate the stee steelKlKss prop proper erti ties es such such as its its hard harden enab abil ilit ityy corr corros osio ionn resi resist stan ance ce stre streng ngth th formability formability weldability or ductility. ductility. Applications Applications for alloys steel include pipelines auto parts transformers power generators and electric motors.
!.3 STAINLESS STEELS
$tainless steels generally contain between 9-;9X chromium as the main alloying element and are valued for high corrosion resistance. :ith over X chromium steel is about ;99 times more resistant to corrosion than mild steel. !hese steels can be divided into three groups based on their crystalline structure Aust Austen enit itic ic Auste usteni niti ticc stee steels ls are are nonnon-ma magn gnet etic ic and and non non heat heat-t -tre reat atab able le and and generally contain GX chromium GX nickel and less than 9.GX carbon. Austenitic Austenitic steels form the largest portion of the global stainless steel market and are often used in food processing e1uipment kitchen utensils and piping. !.3.1 F--) "erritic
steels contain trace amounts of nickel ;-
alum alumin inum um or tita titani nium um.. !h !hes esee magn magnet etic ic stee steels ls cann cannot ot be hard harden ened ed with with heat heat treatment but can be strengthened by cold working. !.3.1 M*-)+) 7artensitic
steels contain -
!.4 T S)
!ool steels !ool steels contai containn tungst tungsten en molyb molybden denum um cobalt cobalt and vanadi vanadium um in varyin varyingg 1uantities to increase heat resistance and durability making them ideal for cutting and drilling e1uipment. $teel products can also be divided by their shapes and related applications Bong!ubular )roducts include bars and rods rails wires angles pipes and shapes and sections. !hese products are commonly used in the automotive and construction sectors. "lat )roducts include plates sheets coils and strips. !hese materials are mainly used in automotive parts appliances packaging shipbuilding and construction. +ther )roducts include valves fittings and flanges and are mainly used as piping materials. !.5 HEAT TREATMENT
!he heat treatment given to a steel can affect its properties too. Cooling a red-hot tool steel rapidly in cold water makes it harder and more brittle. :e could have made the same piece of metal softer by keeping it at red heat for longer and then cooling it slowly. 5eat treatment is another method that the steelmaker uses to make the properties of the steel match the job it has to do. !here are many types of heat treating processes available to steel. !he most common are annealing 1uenching and tempering. Annealing is the process of heating the steel to a sufficiently high temperature to soften it. !his process goes through three phases recovery recrystalli0ation and grain growth. !he temperature re1uired to anneal steel depends on the type of annealing to be achieved and the constituents of the alloy. 4uenching and tempering first involves heating the steel to the austenite phase then 1uenching it in water or oil. !his rapid 46
cool coolin ingg resu result ltss in a hard hard but but brit brittl tlee mart marten ensi siti ticc stru struct ctur ure. e. !h !hee stee steell is then then tempered which is just a speciali0ed type of annealing to reduce brittleness. In this this appl applic icat atio ionn the the anne anneal alin ingg (tem (tempe peri ring ng proc proces esss tran transf sfor orms ms some some of the the martensite into cementite or spheroidite and hence reduces the internal stresses and defects. !he result is a more ductile and fracture-resistant fracture-resistant steel.
!.6 HARDNESS
5ardness is regarded as the resistance of a material to indentations and scratching. !his is generally determined by forcing an indenter on to the surface. !he resultant deformation in steel is both elastic and plastic. !here are several methods using which the hardness of a metal could be found out. !hey basically differ differ in the form of the indenter which is used on to the surface. !. STRESS
In continuum mechanics )- is a measure of the internal forces acting within a deformable body which either reversibly or irreversibly changes its shape. It is a measure of the average force per unit area of a surface within the body on which internal forces act. !hese internal forces arise as a reaction to e&ternal forces applied to the body. !hese internal forces are distributed continuously within the volume of the material body and result in deformation of the body shape. 'eyond limits of material strength this can lead to a permanent shape change or structural failure. !he dimension of stress is the same as that of pressure and therefore the $I unit for stress is the )ascal ()a which is e1uivalent to one #ewton per s1uare meter (#mY. In Imperial units stress can be measured in pound-force per per s1uare inch which which is abbreviated as psi. psi.
47
48
CHAPTER " MATERIAL MATERIAL PROPERTIES ".1 STRENGTH
!he ability of a material to stand up to forces being applied without it bending breaking shattering shattering or deforming deforming in any way. way. ".2 ELASTICITY
!he ability of a material to absorb force and fle& in different directions returning to its original position. ".3 PLASTICITY
!he ability of a material to be change in shape permanently. permanently. ".4 ".4 DUCT DUCTIL ILIT ITY Y
!he ability of a material to change shape (deform usually by stretching along its length. ".5 TE TENSILE ST STRENGTH
!he ability of a material to stretch without breaking or snapping. P->-) ? *)-* P->-)=
9. to 9.;X .89 to .<9X 9.9 to 9.8/X 9.989X (ma& 9.989X (ma&
". MODULUS OF ELASTICITY
An elastic modulus or modulus of elasticity is a number that measures an object or substanceK substanceKss resistance resistance to being deformed deformed elastical elastically ly (i.e. (i.e. non-perm non-permanen anently tly when a force is applied to it. !he elastic modulus of an object is defined as the slope of its stressHstrain curve in the elastic deformation region. A stiffer material will have a higher elastic modulus. An elastic modulus has the form where stress is the force causing the deformation divided by the area to which the force is applied and strain is the ratio of the change in some length parameter caused by the deformation to the original value of the length parameter
\P
stress strain
50
%oungKs modulus describes the relationship between stress (sigma and strain (epsilon in a material that obeys 5ookeKs law. !hat means that there is a linear elastic relationship between stress and strain (which means that for a given change in strain there will be a linearly proportional change in internal stress. It is also known as the tensile modulus or elastic modulus is a measure of the stiffness of an elastic material and is a 1uantity used to characteri0e materials. It is defined as the ratio of the stress (force per unit area along an a&is to the strain (ratio of deformation over initial length along that a&is in the range of stress in which 5ookeKs law holds. %oungKs modulus is the most common elastic modulus sometimes called the modulus of elasticity but there are other elastic modulus such as the bulk modulus and the shear modulus. ".! POISSONS RATIO
)oissonKs ratio is the ratio of the relative contraction strain (or transverse strain normal to the applied load to the relative e&tension strain (or a&ial strain in the direction of the applied load. P+ R*) *+ >- *
:here
] P - ^t ^l
] P )oissonKs ratio ^t P transverse strain ^l P longitudinal or a&ial strain
S)-*+ *+ >- * ^ P dl B
:here dl P P change in length (m ft B P initial length (m ft "or most common materials the )oissonKs ratio is in the range 9 - 9./. 51
"." YIELD STRENGTH
A yield strength or yield point of a material is defined in engineering and materials science as the stress at which a material begins to deform plastically. )rior to the yield point the material will deform elastically and will return to its original shape when the applied stress is removed. +nce the yield point is passed some fraction of the deformation will be permanent and non-reversible ".10 ULT U LTIMATE IMATE STRENGTH
Dltimate tensile strength (D!$ often shortened to tensile strength (!$ or ultimate strength is the ma&imum stress that a material can withstand while being stretched or pull pulled ed befo before re fail failin ingg or brea breaki king ng.. !ensil nsilee stre streng ngth th is not not the the sam same as compressive strength and the values can be 1uite different. $ome materials will break sharply without plastic deformation in what is called a brittle failure. +thers which are more ductile including most metals will e&perience some plastic deformation and possibly necking before fracture. !he D!$ !he D!$ is usua usuall llyy foun foundd by perf perfor ormi ming ng a tens tensil ilee test test and and reco record rdin ingg the the engineering stress versus strain. !he highest point of the stressHstrain curve is the D!$. It is an intensive property@ therefore its value does not depend on the si0e of the the test test spec specim imen en.. 5owe 5oweve verr it is depe depend nden entt on othe otherr fact factor ors s such such as the the preparation of the specimen the presence or otherwise of surface defects and the temperature of the test environment and material. !ensile strengths are rarely used in the design of ductile members but they are important in brittle members. !hey are tabulated for common materials such as alloys composite materials ceramics plastics and wood. !ensile strength is defined as a stress which is measured as force per unit area. "or some nonhomogeneous materials (or for assembled components it can be reported just as a force or as a force per unit width. ".11 DENSITY
A materialKs materialKs density is defined as its mass per unit volume. _P
m V
52
CHAPTER 10 LIMITATION OF USE •
:orking load limit (:BB should never be e&ceeded.
•
5ook-blocks should be used in vertical lift only.
•
*igging blocks should be used only as in design specifications. 'locks should not be used for towing unless specifically designed and marked for that purpose.
•
$wivels should be used in either vertical or hori0ontal plain only.
•
5ori0ontal and vertical lead sheaves used only as indicated in description.
•
$hock or side loading should not be applied unless e1uipment is designed for that purpose. Boad should always be in seat of hook or eye. N/- *) >+)
53
CHAPTER 11 CONCLUSION
"or "or the the eval evalua uati tion on of stre streng ngth th and and dura durabi bili lity ty of machi achine ne elem elemen entt stre stress ss concentration factor are generally used. In order to optimi0e the weight of the crane hook the stress induced in crane hook must be studied. !he review of previous research permits to conclude that the curved beam such as crane hook needs more broad investigation since very few articles in this field have been published yet. !he study of earlier publication enables us to conclude that it is possible to remove unwanted material where stress concentration is low and for that "inite Element 7ethod ("E7 is one of the most effective and powerful method for the stress analysis of the crane hook.
54
CHAPTER 12 REFERENCES
` %u %u 5uali 5.B. and 5uang Jie1ing >$tructure-st rength of 5ook with Dltimate Boad by "inite El Elem emeent 7ethod? )roceedings of the International 7ultiConference 7ultiConference of Engineers and Computer $cientists ;99= 2ol 2ol II I7EC$ ;99= 7arch G - ;9 ;99= 5ong Fong. `; Advanced 7echanics of 7aterials? by A ) 'ores i and + 7 $idebottam ohn :iley :iley and $ons th Ed. =G/ I$'# 9-<-G8;8-<. `8 `8 I# I# / 9 9 )art )art Bift Biftin ingg hook hookss for for lift liftin ingg appl applia ianc nces es@@ sing single le hook hooks@ s@ Dnmachined parts eutsche #orm =G;. ` *ashmi Dddanwadiker >$tress Analysis of Crane 5ook and 2alidation by )hoto-Elasticity? )hoto-Elasticity? Engineering ; 9 9 8 =8/-=. `/ >$trength of 7aterials? by $adhu $ingh =th Ed . ;99G I$'# #o G-<9=9G-<. ` httpwww.steel-tube-steel-pipe.com)rcoducts$tE-8//-%oungs-modulus.html `< I# / 99 Bifting hooks@ materials mechanical properties lifting capacity and stresses eutsche #orm ==9.
