Bolt Count for Shear
Calculate the number of bolts needed to resist a shear force, n = F ÷ (A·τ_adm), from the total shear force to transmit F (N), each bolt's area A (mm²) and the material's allowable shear stress τ_adm (MPa). In structural and mechanical connections loaded in shear (beam splices, truss connections, flanges under lateral load, splice plates), the force is distributed among several bolts, each working in shear. The number needed is the total force divided by one bolt's shear capacity (area × allowable stress). The result is rounded up, and in practice a quantity is adopted that also meets minimum bolt spacing, edge distance and connection symmetry criteria. This calculation is the basis of designing bolted connections in steel structures (where it competes with welding) and in machines: it sets how many bolts and of what diameter are needed. There are other checks in the same connection: plate BEARING (contact pressure on the hole wall, which can tear the plate before the bolt shears), edge tear-out and the plate's own net-section strength (minus the holes). But bolt shear is the starting point. Enter the shear force, each bolt's area and the allowable stress.
Result
—
Número de parafusos ao cisalhamento
O número de parafusos necessários para resistir a uma força cortante é n = F ÷ (A·τ_adm), a partir da força cortante total a transmitir F, da área de cada parafuso A e da tensão de cisalhamento admissível do material τ_adm. Em ligações estruturais e mecânicas solicitadas ao corte (emendas de vigas, ligações de treliças, flanges sob carga lateral, talas), distribui-se a força entre vários parafusos, cada um trabalhando ao cisalhamento. O número necessário é a força total dividida pela capacidade de corte de um parafuso (área × tensão admissível). O resultado é arredondado para cima, e na prática adota-se uma quantidade que também atenda a critérios de espaçamento mínimo entre parafusos, distância às bordas e simetria da ligação. Este cálculo é a base do dimensionamento de ligações aparafusadas em estruturas de aço (onde compete com a soldagem) e em máquinas: define quantos parafusos e de que diâmetro são necessários. Há ainda outras verificações na mesma ligação: o esmagamento da chapa (pressão de contato na parede do furo, que pode rasgar a chapa antes de o parafuso cisalhar), o rasgamento da borda e a resistência da própria chapa na seção líquida (descontando os furos). Mas o cisalhamento dos parafusos é o ponto de partida. Informe a força cortante, a área de cada parafuso e a tensão admissível.
Related Tools
Bolt Shear Stress
Calculate the shear stress in transversely loaded bolts, τ = F ÷ (n·A), from the total shear force F (N), the number of bolts (or shear planes) n and each bolt's area A (mm²). Unlike tensioned joints (where the bolt is tightened and the load is axial), in SHEAR joints the bolts resist a transverse force tending to slide one part over another (as in steel structural connections, splice plates, flanges under lateral load). The force is distributed among the bolts and each works in shear — hence the stress is force divided by the number of bolts times the area. There can be SINGLE shear (one shear plane) or DOUBLE shear (two planes, when the bolt passes through three plates), doubling capacity. The area used depends on whether the shear plane passes through the threaded part (use the tensile area) or the smooth shank (nominal-diameter area). Shear stress is compared with the bolt material's shear strength (typically ~0.6 of tensile strength). In structures, bearing-type (bolt in shear/bearing) and slip-critical (preload friction transmits load without bolt shear) connections are distinguished — this formula covers shear resistance. Enter the shear force, the number of bolts and the area.
Chip Shear Angle
Calculate the shear-plane angle in chip formation, φ = arctan[(r_c·cos α) ÷ (1 − r_c·sin α)], from the cutting ratio r_c (undeformed chip thickness ÷ deformed chip thickness, always < 1) and the tool rake angle α (degrees). In the orthogonal cutting model (the basis of machining theory), material is not 'scraped': it undergoes intense SHEAR deformation along an inclined plane — the shear plane — where it turns from part to chip almost instantly. That plane's angle, φ, is a central measure of cutting mechanics: LARGER shear angles mean thinner chips, less deformation, lower cutting force and energy and less heat — all desirable. The angle depends on the cutting ratio (measured by comparing chip thickness to feed) and the tool rake angle: tools with more positive rake give larger shear angles and cut with less effort (but have a more fragile edge). Merchant's theory relates φ to chip-tool friction and rake angle, and predicts the angle that minimizes energy. From chip measurements, this calculation lets you analyze cutting efficiency and the influence of tool geometry and lubrication. Enter the cutting ratio and the rake angle.
Punching Force (Sheet Cutting)
Calculate the force to punch (cut) a round hole in sheet metal, F = π·D·t·τ, from the hole diameter D (mm), sheet thickness t (mm) and the material shear strength τ (N/mm²). The product π·D is the cut perimeter; times thickness gives the area to be sheared; times shear strength gives the force. Punching (and sheet cutting in general, like blanking) is one of the most common stamping operations: a punch descends against a die, with a small clearance, and shears the material, separating the part or scrap. Computing the force is essential to select the press (whose tonnage capacity must exceed the force with margin) and to size the tooling. Force can be reduced with tricks like adding a shear angle to the punch or die, making the cut progressive instead of simultaneous over the whole perimeter — reducing the peak force (but increasing stroke). Knowing the force also lets you estimate the operation's work and energy. Enter the hole diameter, thickness and shear strength.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.