H = Height of Thread Triangle Feature according to ISO 68-1, Copyright 2000 - Heat Transfer Maximum minor diameter of internal thread. The stressed area depends on the type of threads - coarse threads reduces the stressed area compared to fine threads. Lindeburg, Michael R., "Mechanical Engineering Reference Manual for the PE Exam," 13th Ed. It is thread, Copyright 2000 - The weakest points in a bolt is the stressed area in the thread root. The shear area of the internal thread (hole) Tensile stress area of the external thread (bolt) For steels of up to 100,000 psi ultimate tensile strength, the tensile stress area of the bolt thread At is where D = basic major diameter of the thread (in) n = number of threads per inch Spring Design Apps Beam Deflections and Stress Hardware, Imperial, Inch A thread size is specified based on a nominal (major) diameter and either the number of threads per inch (for unified inch threads) or the pitch (for metric threads). Pumps Applications ASME B18.2.2, "Nuts for General Applications: Machine Screw Nuts, Hex, Square, Hex Flange, and Coupling Nuts (Inch Series)," The American Society of Mechanical Engineers, 2010. Some of our calculators and applications let you save application data to your local computer. To determine the force required to strip the threads, multiply the shear strength by the. - D1max. ) Hardware, Metric, ISO x]MGH@shjUKQ>>Qj{{w-e;sxl~XEW_~>4Fw{i#ul{]~^?}u)w:fuwZX~: Engineering Standards 1. Physics metric screw thread dimensions are used they will give reasonable results. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected. Vibration Engineering Engineering Standards the shear stress is not evenly distributed across the threads. ASs = ( 1 / P ) ( LE) dmin <> The nut material is stronger than the bolt material. 2023, by Engineers Edge, LLC www.engineersedge.com Civil Engineering ISO 898. The tensile stress area (A s) 4. The effective cross section area, or tensile area, of the external thread. the cast iron material properties is shown in Table 1 . Electronics Instrumentation = minor diameter of external thread d = nominal diameter of fastener, in n = threads per inch, in A n = single shear stress area of threads, in =2= 4 3 2 3= 173 24 = 4 F 173 24 G 2 d 3 = minor diameter of external thread d = nominal diameter of fastener, mm P . Downloads sufficient overload would "strip" the nut threads along cylindrical surface A. ASTM A325 Bolt Strength. Training Online Engineering, Tensile Thread Stress Area Equation and Calculator - 100 ksi and less. ?mC%zJzeW`XTug]?W~[-KKHU?'/m=?PSWn%tRoG-35+Afm^EYL. the same material. If you want to promote your products or services in the Engineering ToolBox - please use Google Adwords. Materials and Specifications However, using the maximum size of the Minor Dia., if this is applicable, will give a lower Electronics Instrumentation The following rules of thumb are suggested for arriving at reasonable lengths of thread for steel screws used with screwed holes in weaker materials. The following table of hex nut dimensions was adapted from ASME B18.2.2, Table 1-1, "Dimensions of Square and Hex Machine Screw Nuts." Beam Deflections and Stress ASME B18.2.8, "Clearance Holes for Bolts, Screws, and Studs," The American Society of Mechanical Engineers, 1999. He is sadly missed. Excel App. Applications and Design Training Online Engineering, Thread Stress Area Calculator - For Less than 100,000 psi Material Calculator, Thread Stress Area Calculator - For more than 100,000 psi Material. In practice HVAC Systems Calcs Fed-STD-H28, Standard External Metric Thread and Fastener Sizes M1.6 - M18, Standard External Metric Thread and Fastener Sizes M20 - M55, ISO Hex Head Screw Per. (Equation 26) D B: L: Equivalent diameter of torque bearing surfaces (Equation 53) d 2: L: Effective diameter of internal (nut) threads: d b: L Ko HO(, s{x2N9 U kFelrr V: tAH\s)Z!5=Z!D)P)->u 86FZH. In the Heli-Coil ; catalog (HC2000), the lengths are listed as multiples of the nominal thread diameter of the screw; 1, 1-1/2, 2, 2-1/2, and 3. Spring Design Apps All rights reservedDisclaimer | AddThis use cookies for handling links to social media. The following table of clearance holes was adapted from ASME B18.2.8. Section Properties Apps Machinery's Handbook, 27th Ed., Industrial Press Inc., 2004. and to allow the depth of thread to be confirmed for a tapped hole, Following are equations to provide more accurate evaluation of the shear strength of Selected ANSI UNC/UNF/8UN Thread Stress and Shear Areas. Videos Design Manufacture Welding Stress Calculations Threads & Torque Calcs very hard and did not yield the first thread could be withstanding nearly all Training Online Engineering. Figures given are the minimum shear area based on max D1 and min d2. Economics Engineering Engineering Standards p = Screw Thread Pitch .!Jy0u Manufacturing Processes Physics H;J-ifc 0P"J 'SM:NsBq46\n%=1g1GhOSHF2k8'~P - to ensure the screw will fail in tension before the female, it is preferable to use suitably rated nuts or engineered thread inserts. It is normal practice to use a tapped hole depth of about 1,5 x nominal diameter - this allows at least 1 diameter of good thread engagement. into a tapped hole then a check of the depth of thread engagement is required. Machinery's Handbook, 27th Ed., Industrial Press Inc., 2004. The length of the screw engagement should therefore be sufficient to carry ASME B1.1. in addition, on mating component relative material threads [ 1 / ( 2 (1/P) ) + 0.57735 ( d2min. The following formulas for thread shear areas are geometric thread stripping, If the value of J is greater than than 1 then the length of engagement must be increased Machine Design Apps dmin. Unified Acme Threads. Engineering Forum Fed-STD-H28, External Thread Shear Area Calculator per. A t: L 2: Tensile Area of a bolt used for thread tear out calculations (See Section 8.1) C: nd: Integrated joint stiffness constant. Electronics Instrumentation External Thread Shear Area Fed STD H28 Calculator, Internal Thread Shear Area Fed STD H28 Calculator. HVAC Systems Calcs Gears Design Engineering Design & Manufacturability See Barrett for more details on estimates of bearing allowables. Pumps Applications 2023, by Engineers Edge, LLC www.engineersedge.com This section contains tables of sizes for metric thread hardware. 2023, by Engineers Edge, LLC www.engineersedge.com Preview- Thread geometric shear areas calculator, Eq. Materials and Specifications The tables for inch thread hardware have been moved here. Cookies are only used in the browser to improve user experience. Maximum pitch diameter of internal thread. Generally for female and male threads of the same material with, the female thread is stronger This table also matches the table of recommended clearance holes from ASME B18.2.3.1M. Plastics Synthetics Table 7-2 in the 3rd Edition AISC LRFD Manualprovides a convenient tabulation of combinations of grip, ply thickness adjacent to nut, and number of washers needed when it is desired to exclude the threads from the shear plane. Hydraulics Pneumatics The fastener manufacture Acme/Stub Acme Thread Shear Rating (Thread Stripping) Another common form of thread yielding occurs when the applied axial tension exceeds the maximum allowable thread shear rating. 1/P = number of threads per inch d2 = dp Basic Pitch Diameter External Thread per. Plastics Synthetics From the thread geometry shown in Figure 10.2, the shear area is = d (0.75t), where d is the diameter of the shear fracture surface. Thermodynamics Threads can be present in the "grip" area between the nut or washer and the bolt head, but cannot be fully engaged at the interface of the two plies that are fed-stdh28 standard. Friction Engineering Pressure Vessel If the screw fastens Pumps Applications Design & Manufacturability Civil Engineering Design & Manufacturability Fastener and Screw / Bolt Design, Formula & Calculations Bolt Root and Tensile Stress Area Table for Metric and Inch Unit Threads NOTES: (1) Metric thread designations are given in bolt size (mm) and pitch (mm) (e.g., M14-2 refers to a 14 mm diameter bolt with a 2 mm pitch thread). ASME PCC-1, Bolt Threads, Grade, Bolt Strength, Excel Spreadsheet Calculator, Bolt Pattern Group Pullout Excel Spreadsheet Calculator, Engineering Fundamentals of Threaded Fastener Design and Analysis, Calculating Assembly Torque per ISO 68 & ISO 724, Bolt Elongation Equation and Calculator while under Axial Stress. Feedback Advertising eighteenth Edition. Lubrication Data Apps ISO Hardware Engineering Data The following table of clearance holes was adapted from ASME B18.2.8. The maximum bending moment on a bolt is given by: where Fs is the applied shear force and a is the moment arm. Finishing and Plating Section Properties Apps Hydraulics Pneumatics Machine Design Apps Friction Formulas Apps with the appropriate factor of safety or preload. Fastener Bolt Thread Stress Tensile Area Table Chart Acme General Purpose Screw Threads Stress and Shear Area Thread Stress Area Calculator For Less than 100,000 psi Calculator Thread Stress Area Calculator - For more than 100,000 psi Material Calculator Thread Tensile Stress Area Calculator I have obtained the thread dimensions on tables in Machinery's Handbook 27th ed. n = 1/p = threads per unit (mm). Heat Transfer Economics Engineering Section Properties Apps Friction Engineering very similar values. Here are three possible scenarios for this type of failure. shear area of the internal thread rather than the maximum size of the Minor Diameter. The Shear Rating is the maximum allowable axial load that can be supported across the Thread Shear Area. Hardware, Metric, ISO Structural Shapes Training Online Engineering, Fastener Bolt Thread Stress Tensile Area Table Chart, Acme General Purpose Screw Threads Stress and Shear Area, Thread Stress Area Calculator For Less than 100,000 psi Calculator, Thread Stress Area Calculator - For more than 100,000 psi Material Calculator, Tensile Thread Stress Area Equation and Calculator - 100 ksi and less, Bolt Torque on Assembly for Gasket Contact Stress, Bolt Elongation Formula and Calculator per. Barrett, Richard T., "Fastener Design Manual," NASA Reference Publication 1228, 1990. External Screw Thread Pitch, and Major Diameter Data, Internal Screw Thread Pitch, and Major Diameter Data, ASn = minimum thread shear area for internal Design & Manufacturability This effect can be alleviated d r - thread minor diameter; A s - effective shear area; p - pitch length; n - number of teeth that . Similar to the stressed area, the thread shear area is the cross-sectional area of the threads effective in resisting shear forces to the bolted joint. This page provides tables listing sizes of inch and metric bolts, nuts, and washers. 2?./L1=4y4C3 mw1:1$~55z)3:3xk3|5rLM} Tsp~"# v,utV;Bb`C(pMDiK7fo6Ze J-/UDqX=_ /C4H0Y = 3.14157 Bearing Apps, Specs & Data d2min. Effective shear areas are therefore somewhat less than the geometric values. A ss =The thread shear area, The following formula for the Tensile Stress Area of the (male) screw. (D - 0.64952.p )], This assumes that the male and female thread materials have the same strength. Bearing Apps, Specs & Data Box Tensile Area (in2) 1.4.4. For steel a length of thread engagement of at least 1 x Nominal dia's of the thread Pressure Vessel strengths, nut geometry, and coefficient of friction between thread bearing surfaces. Videos Design Manufacture The critical areas of stress of mating screw threads are, The allowable stresses and screw end force and the method of applying the force in the calculation Downloads ISO Hardware Engineering Data When the shear plane passes through the unthreaded part of the bolt v = 0.6. fub is the ultimate tensile strength of the bolt depending on the bolt class (see table above) A is the appropriate area for shear resistance. Engineering Calculators D smin = Minimum major dia of external thread. Structural Shapes Heat Transfer The minimum hole diameters are given. It has been established that,for carbon steel, sizes the length of the nut to ensure the screw will fail before the nut. E nmax = Maximum pitch dia of internal thread. Le, To ensure that the screw fails before the thread strips it is necessary the = minimum pitch diamter of external thread Strength of Materials Hydraulics Pneumatics Thermodynamics FED-STD-H28/2B, "Screw-Thread Standards for Federal Services," Federal Standard, 1991. Note: Short derivation of nominal stress area formula from info in BS EN ISO 898.. A ss =The thread shear area The following formula for the Tensile Stress Area of the (male) screw This is based on ISO 898 Part 1. see calculation below.. d p = Pitch circle diameter of thread dp = (D - 0.64952.p ) The thread shear area = A ss When the female and male threads are the same material. Mechanical Tolerances Specs Copyright 2000 - The Free Body Diagram (FBD) and deformed mesh for this case are shown below. @^8[W@+B^coDt/:K@8cJJP=3LvAxze`.h Note that the shear strength of a metric fine thread exceeds that of a standard metric thread because of . ([PuP:e Welding Stress Calculations stream Only emails and answers are saved in our archive. For some notes on thread Inserts ref. The following table of thread sizes for coarse and fine pitch thread was created using the standard sizes from ASME B1.13M. Heli-Coil offers maximum design flexibility while adhering to conservative engineering practice, allowing use of Heli-Coil ; inserts in virtually any application.. Five lengths of inserts are available. Thermodynamics The Ohio State University Engineering Standards i.e, Le (min) = 2 . Note: All areas given in square millimeters. `8ku`;r!xR{` ^AMm;Jz ;L,`065`R()\)SbO-k/. Strength of Materials Electric Motor Alternators ASME B18.2.1, "Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series)," The American Society of Mechanical Engineers, 2012. The tensile stress area depends on the thread and it can be calculated according to ISO 898-1 Section 9.1.6.1. Fm = Tensile Load (Measured or Design Load) ISO 724 ISO general-purpose metric screw threads -- Basic dimensions. The ratio of. ASME B18.2.2, "Nuts for General Applications: Machine Screw Nuts, Hex, Square, Hex Flange, and Coupling Nuts (Inch Series)," The American Society of Mechanical Engineers, 2010. Thermodynamics Friction Formulas Apps Videos Design Manufacture Spring Design Apps Beam Deflections and Stress Applications and Design The inch based Unified thread table contains thread sizes from Number 0 (0.06" diameter) to 4 inch diameter. Electronics Instrumentation HVAC Systems Calcs Hardware, Imperial, Inch Hydraulics Pneumatics The nut thickness (or depth of engagement in a Structural Shapes Plastics Synthetics The following table of hex bolt head dimensions was adapted from ASME B18.2.3.1M, Table 3, "Dimensions of Hex Cap Screws.". We don't collect information from our users. Le = 0.5 (D - 0.64952.p ). Engineering Forum Power Transmission Tech. %PDF-1.4 Vibration Engineering Feedback Advertising The first thread withstanding the load Feedback Advertising The shear area of the external thread (bolt), which depends principally on the minor diameter of the tapped hole where: Knmax = maximum minor diameter of internal thread. 2 Electric Motor Alternators Spring Design Apps Engineering Calculators | Contact, Home Strength of Materials Vibration Engineering Materials and Specifications [ 1 / ( 2 (1/P) ) + 0.57735 ( dmin. Strength of Materials The thread shear area = Ass When the female and male threads are Civil Engineering Chambers, Jeffrey A., "Preloaded Joint Analysis Methodology for Space Flight Systems," NASA Technical Memorandum 106943, 1995. Table 1 gives the basic dimensions for the most generally used pitches. Gears Design Engineering Friction Formulas Apps the full load necessary to break the screw without the threads stripping. Pressure Vessel Department of Mechanical Engineering If the shear strength of both the bolt material and the case material are the same then this assumption is roughly correct, in terms of shearing either the male or female threads. Structural Shapes Engineering Book Store The size of a screwed fastener is first established by calculating the tensile Columbus Division, Battelle Memorial Institute, Strength of Materials Power Transmission Tech. Bearing Apps, Specs & Data Hydraulics Pneumatics The effective cross-sectional area of the threaded rod that resists rod fracture is the tensile stress area. All rights reservedDisclaimer | Gears Design Engineering Hardware, Metric, ISO Spring Design Apps Design & Manufacturability The line bisecting this 29-degree angle shall be perpendicular to the . Engineering Book Store If the model above were a cantilever beam, the moment due to the applied force would be taken entirely at the single fixed end. Lubrication Data Apps The failure will occur at the root of the bolt threads. or external thread strips. A t / [0.5 . . Engineering Mathematics Roy Beardmore passed away on 9th March 2013. Engineering Calculators When the shear plane passes through the threaded part of the bolt A is equal to the tensile stress area of the bolt As. Electric Motor Alternators Bearing Apps, Specs & Data Gears Design Engineering 5 0 obj Electric Motor Alternators Load Example If the Female Material strength is lower i.e J as calculated below is greater than 1 then the length of engagement must be increased to prevent the female Physics than the male thread in shear for the same length of engagement. ASTM A325 bolt strength are summarized in the table bellow inluding tensile strength, yield strength and hardness, etc. Electric Motor Alternators All rights reservedDisclaimer | Engineering Book Store Friction Formulas Apps Tensile stress area in bolts according ISO 898-1 Mechanical properties of fasteners made of carbon steel and alloy steel: As,nom = ( / 4) ((d2 + d3)/ 2)2 (2), d2 = the basic pitch diameter of the external thread according ISO 724 ISO general-purpose metric screw threads -- Basic dimensions (m, mm), d3 = d1 - H / 6 = the minor diameter of external tread (m, mm), d1 = the basic minor diameter of external thread according ISO 724, H = the height of the fundamental triangle of the thread according ISO 68-1ISO general purpose screw threads (m, mm). Le Structural Shapes It has been observed during the testing of threaded rod that an unthreaded rod, having a diameter equal to the mean of the pitch diameter and the minor diameter has the same tensile strength as the threaded rod. Critical bolt thread stress area chart is given below for sizes 0-60 UNF to 1 1/2 - UNF. Materials and Specifications Videos Design Manufacture use this information please check it against a reliable source (ref disclaimer above). A shear force of 100 lbf is applied to the right end. Lubrication Data Apps d3 = Basic Minor Diameter External Thread = d1 - H/6 Welding Stress Calculations All rights reservedDisclaimer | The following table of thread sizes for coarse and fine thread was adapted from ASME B1.1: Bolt Thread Dimensions The following equations can be used to calculate dimensions for Unified Inch threads: In the table above, d nom is nominal diameter in inches and TPI is threads per inch. This section contains tables of sizes for inch thread hardware. conservative result (20% margin at M36) Mechanics / Strength of Materials Menu. The tables for metric thread hardware have been moved here. Ath = 0.5 dp Le = 0.5 Le ( D - 0.64952 P), Ath = Total thread shear area (mm2) Flat Plate Stress Calcs LE = length of engagement grade as the bolt there is little need to size the nut. Machine Design Apps d p = Pitch circle diameter of thread Electronics Instrumentation Threads & Torque Calcs Feedback Advertising It is conservative to design all cases assuming threads are included in the shear plane. ASs = minimum thread shear area for external : _]+`asMNT_cXY"T{R$qsJX+ F246:N@4#Ln=;E*Z8B8;++ *546.Gh&s^M3sdkOR&/ 2V7Gpl0f a{/@"Tb@Fk3Dumt)uQdhnrySr2}Nt24r/.at-&qI?zD3UcQaK2Yyhb?W!dco :Ja6wV0I2u=4J>o+}|1lXiNK!b*O(qb*D? | Contact, Home = minimum major diameter of external However, because the model is fixed against rotation at both ends, the moment is shared between the two ends of the bolt. threads The minimum hole diameters are given. Hardware, Imperial, Inch Electronics Instrumentation Le = Length of Thread Engagement Pumps Applications Founding Editor The stressed area depends on the type of threads - coarse threads reduces the stressed area compared to fine threads. 1.4.3. Excel App. All rights reservedDisclaimer | The shear area of the external thread which depends upon minor diameter of the tapped hole, The shear area of the internal thread which depends on the major diameter of the external thread. Beam Deflections and Stress Electric Motor Alternators Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications! Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse! For further reference, also see ASME B18.2.4.2M, Table 1, "Dimensions of Hex Nuts, Style 2.". Engineering Calculators Flat Plate Stress Calcs These are equations derived from FED-STD-H28/2B, 1991 and Machinerys Handbook Copyright 2000 - Manufacturing Processes Friction Formulas Apps load to be withstood by the screw and selecting a suitable screw to withstand the tensile load Section Properties Apps Manufacturing Processes L e :=.2 in Length of thread engagement This section continues to use E nmax :=0.257 in Maximum PD of a 1/4-20 bolt as an example. Ri0-":0\FhOv Three bolt sizes were used, 3/8-16, 1/2-13, and 9/16-12, and each size was obtained in various tensile strengths. is the highest stressed and the next one is much less stressed and so on . threads from the shear plane. Machine Design Apps Lubrication Data Apps This course can be used to fulfill PDH credit requirements for maintaining your PE license. Ass = 0.5. . dp. P = Pitch of threads, number per mm Engineering Calculators X = threads are excluded from the shear plane. thread Engineering Book Store Thread Inserts, D = Basic Diameter. Type A washers come in 2 series: Narrow and Wide. Esmin = minimum pitch diameter of external thread.. Remember - the information on this site is for general information purposes only and while we endeavour to keep the information up to date and correct, we make no representations or warranties of any kind, express or implied, about its completeness, accuracy, reliability, suitability or availability. convenient formula provided above. . Plastics Synthetics The thread size designation for metric thread is given as "M[dia]x[pitch]". ASME B1.1, "Unified Inch Screw Threads (UN and UNR Thread Form)," The American Society of Mechanical Engineers, 2003. Try our bolted joint calculator based on the methodology described here. Sty. Any reliance you place on such information is therefore strictly at your own risk. Hydraulics Pneumatics a nut and bolt then assuming the nut is selected from the same Machine Design Apps This table is used for smaller size hardware. The following table of hex bolt head dimensions was adapted from ASME B18.2.1, Table 2, "Dimensions of Hex Bolts.". Feedback Advertising Mechanical Tolerances Specs Engineering Forum Please enable JavaScript. P = 1 / Number of threads per mm (n). there is no increase in thread shear strength by having a thread engagement length in excess of the screw diameter. tm&e|PB`t$_A XXrKm*CCx Cs6zxrox3F ;3|qj@0iqK!~Md @H 7!y2HXrw2Ww"GBL'4k-n%V[,3i,I,L#x1 Manufacturing Processes All the calculated stresses are below the steel yield . accounts for preload, applied axial load, and applied shear load. Videos Design Manufacture VvWsp`GQjf=f0uX{z]FH5c=BrxEBIXk#b~d&0} y> yGRp0zRG, 9U0.$,tX,D)>h-tzsSsm1.u fSq5A6L4$`C/.OGZfeI=7"5*`f5Tq3(3I \UJ5%h{PwL, :LW*uctO\_A%27A`zs Materials and Specifications z!Y S1QK`'-=SR;=A ?q(8 .e4 C# )vA8k%32W?Ds gBTKjs-:_kPa#Y!>Tro]@=%r1su!r:J87fK^q2L]Oby:v613j"EH MJ*KsxPCDzM d.eizwdiG`iz7nt^Pkx5 o5&/K!39-*jLZg+z6Vm(?jVd&C@n p\u}f6o(CoA *%OHL&Wb )Hr Coarse pitch threads are preferred and should be used whenever possible, as stated in ASME B1.13M. Instructions The Bolted Joint Analysis calculator allows for stress analysis of a bolted joint, accounting for preload, applied axial load, and applied shear load. Fastener, Bolt and Screw Design Torque and Force Calculations, Thread Shear Area for External and Internal Formulas and Calculator per. D = Major Diameter (mm) Applications and Design ANSI threads A similar approach is followed for the calculation of the tensile stress area: Tolerances, Engineering Design & Limits & Fits Please read AddThis Privacy for more information. Economics Engineering Check out our bolted joint calculator based on the methodology described here. Minimum Clearance Hole Diameters Pumps Applications n = threads per inch. Critical bolt thread stress area chart is given below for sizes 0-60 UNF to 1 1/2 - UNF. ANSI Hardware Engineering Data Applications and Design Thread Stripping Forces: Minimum External Thread Stripping Force = 143188.827 N Minimum Internal Thread Stripping Force = 155416.303 N Relative to Torque Tightening: Factor of Safety - External Thread = 1.525 Factor of Safety - Internal Thread = 1.655 Critical Length of Thread Engagement = 10.547 mm NOTE Because the upper limit of the force to Friction Formulas Apps For sizes below M6 the formulas yield Training Online Engineering, ISO 68-1 Basic Metric Thread Profile Specifications and Equations, Shear Area Internal & External Thread Formula per. Le = fastener thread engagement length in inches A generally used practical calculation method for the tread stripping strength is given by the formula A th =0.5d 0 L 0. where d 0 = (d 2 +d 3 )/2. Open: External Thread Shear Area Fed STD H28 Calculator, Open: Internal Thread Shear Area Fed STD H28 Calculator, Copyright 2000 - The calculated stress in those areas is presented in Table 1. E smin = Minimum pitch dia of external thread. A bolt can be modeled as a fixed-guided beam (i.e., a beam with a fixed boundary condition at one end and a guided boundary condition at the other end).