91430 SPS cover edited - Electronic Fasteners Inc

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F 1F 1Fig. 10 Force diagrams show the effect of the loading planes of the external load on the bolt load.Fig. 11 Modified joint diagramshows nonlinear compressionof joint at low preloads.60
JOINT DIAGRAMSF eB = Φ F e must be modified to :F eB = n Φ F ewhere n equals the ratio of the length of the clampedparts due to F e to the joint length l j . The value of n canrange from 1, when F e is applied under the head and nut,to O, when F e is applies at the joint center. Consequentlythe stress amplitude:σ B = ±Φ F ebecomes2 A mσ B = ± n Φ F e2 A mGeneral Design FormulaeHitherto, construction of the joint diagram has assumedlinear resilience of both bolt and joint members. However,recent investigations have shown that this assumption isnot quite true for compressed parts.Taking these investigations into account, the jointdiagram is modified to Fig. 11. The lower portion of thejoint spring rate is nonlinear, and the length of the linearportion depends on the preload level F i . The higher F i thelonger the linear portion. By choosing a sufficiently highminimum load, F min >2F e , the non-linear range of the jointspring rate is avoided and a linear relationship betweenF eB and F e is maintained.Also from Fig. 11 this formula is derived:F i min = F J min + ( 1 – Φ) F e + ∆F iwhere ∆F i is the amount of preload loss to beexpected. For a properly designed joint, a preload loss∆F i = – (0.005 to 0.10) F i should be expected.The fluctuation in bolt load that results from tighteningis expressed by the ratio:a= F i maxF i minwhere a varies between 1.25 and 3.0 depending on thetightening method.Considering a the general design formulae are:F i nom = F J min = (1 – Φ) F eF i max = a [ F j min + (1 – Φ) F e + ∆F i ]F B max = a [ F j min + (1 – Φ) F e + ∆F i ] + ΦF eConclusionThe three requirements of concentrically loaded jointsthat must be met for an integral bolted joint are:1. The maximum bolt load FB max must be less thanthe bolt yield strength.2. If the external load is alternating, the alternatingstress must be less than the bolt endurance limit to avoidfatigue failures.3. The joint will not lose any preload due to permanentset or vibration greater than the value assumed for∆F i .SYMBOLSA Area (in. 2 )Am Area of minor thread diameter (in. 2 )A s Area of substitute cyliner (in. 2 )A x Area of bolt part 1 x (in. 2 )d Diameter of minor thread (in.)D c Outside diameter of bushing (cylinder) (in.)D H Diameter of Bolt head (in.)D h Diameter of hole (in.)D J Diameter of JointE Modulus of Elasticity (psi)F Load (lb)F e External load (lb.)F eB Additinal Bolt Load due to external load (lb)F eJ Reduced Joint load due to external load (lb)F i Preload on Bolt and Joint (lb)∆F i Preload loss (–lb)F i min Minimum preload (lb)F i max Maximum preload (lb)F j nom Nominal preload (lb)F B max Maximum Bolt load (lb)F J min Minimum Joint load (lb)K Spring rate (lb/in.)K B Spring rate of Bolt (lb/in.)K J Spring rate of Joint (lb/in.)K x Spring rate of Bolt part l x (lb/in.)l Length (in.)∆l Change in length (in.)l B Length of Bolt (in.)∆l B Bolt elongation due to F i (in.)l J Length of Joint (in.)∆l J Joint compression to F i (in.)l x Length of Bolt part x (in.)Length of clamped partsnTotal Joint Lengthα Tightening factorΦ Force ratioλ Bolt and Joint elongation due to F e (in.)Bolt stress amplitude (± psi)σ B61
Page 1 and 2:
Engineering GuideInch & Metric
Page 3 and 4:
TABLE OF CONTENTSUNBRAKO ® Socket
Page 5 and 6:
INCH QUICK SELECTOR GUIDEPERFORMANC
Page 8 and 9:
SOCKET HEAD CAP SCREWS 1960 Series
Page 10 and 11:
SOCKET HEAD CAP SCREWS 1960 Series
Page 12 and 13: FEWER HOLES TO DRILL AND TAPthree s
Page 14 and 15: SHOULDER SCREWS Dimensions Mechan
Page 16 and 17: FLAT HEAD SOCKET SCREWSDimensionsDe
Page 18 and 19: FLAT HEAD AND BUTTON HEAD SOCKET SC
Page 20 and 21: SOCKET SET SCREWS Dimensions Appl
Page 22 and 23: SOCKET SET SCREWS Point Selection
Page 24 and 25: SOCKET SET SCREWS Torisional and A
Page 26 and 27: PRESSURE PLUGSDRYSEAL TYPE with 3/4
Page 28 and 29: PRESSURE PLUGS Application DataPre
Page 30 and 31: DOWEL PINS Dimensions Application
Page 32 and 33: PULL-OUT DOWEL PINS Dimensions Ap
Page 34 and 35: HEX KEYS Dimensions Mechanical Pr
Page 36 and 37: THREAD CONVERSION CHARTSDIAMETER/TH
Page 38 and 39: UNBRAKO Metric FastenersUNBRAKO Met
Page 40 and 41: METRIC SOCKET HEAD CAP SCREWSDimens
Page 42 and 43: METRIC SOCKET FLAT HEAD CAP SCREWSD
Page 44 and 45: METRIC SOCKET HEAD SHOULDER SCREWST
Page 46 and 47: METRIC SOCKET SET SCREWS Knurled C
Page 48 and 49: METRIC LOW HEAD CAP SCREWSThreads:
Page 50 and 51: ISO TOLERANCES FOR METRIC FASTENERS
Page 52 and 53: CONVERSION CHARTSI UNITS & CONVERSI
Page 54 and 55: INSTALLATION CONTROLSeveral factors
Page 56 and 57: Their disadvantages are… lower te
Page 58 and 59: AN EXPLANATION OF JOINT DIAGRAMSWhe
Page 60 and 61: A s = π (D 2 H - D 2 h )Effect of
Page 64 and 65: TIGHTENING TORQUES AND THETORQUE-TE
Page 66 and 67: STRIPPING STRENGTH OF TAPPED HOLESC
Page 68 and 69: THREAD STRIPPING STRENGTHIN VARIOUS
Page 70 and 71: HIGH-TEMPERATURE JOINTSBolted joint
Page 72 and 73: mine the clamping stress at assembl
Page 74 and 75: Electroplating: Two broad classes o
Page 76 and 77: GALVANIC CORROSIONMMMMMM M M M M M
Page 78 and 79: TABLE 20LOW-TEMPERATURE IMPACT PROP
Page 80 and 81: TYPICAL TENSION IMPACT STRENGTH,EFF
Page 82 and 83: THREADS IN BOTH SYSTEMSThread forms
Page 84 and 85: THROUGH-HOLE PREPARATIONClose Fit:
Page 86 and 87: HARDNESS - TENSILE CONVERSIONINCHRO
Page 88 and 89: ENGINEERING PART NUMBERS - INCHUnbr
Page 90 and 91: PRESSURE PLUG PART NUMBERSBasic Par
Page 92: INDUSTRIAL FASTENERS GROUPUnbrakoTh
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