Translational Detent

Two-way spring lock for translational motion.

blockType: Engee1DMechanical.Elements.Translational.Detent

Path in the library:

/Physical Modeling/1D Mechanical/Brakes & Detents/Translational/Translational Detent

Description

Block Translational Detent It is a two-sided spring lock for translational motion with a ball and a conical recess. The latch slider slides horizontally across the body of the latch. This interaction creates a horizontal shear force. There is a conical recess inside the slider, and a vertical spring is located in the lock housing. The locking ball is located between the spring and the conical recess. The model also provides viscous damping and kinetic friction between the slider and the housing.

The figure shows the geometry of the retainer with a ball and a conical recess.

translational detent 1 ,

where

— depth of the conical recess;
— the radius of the ball;
— half of the corner of the conical recess.

Depending on how you parameterize the block, the shear force model is determined by the geometric and spring parameters, the maximum force and width of the recess, or a table that indicates the dependence of force on relative displacement.

Parameterization of the translational motion lock

If for the parameter Parameterization the value is set By peak force and notch width, then the block ensures the continuity of the curve of dependence of the force and its derivative on the displacement in the fixation area. The maximum force values are in the middle between the center and the edges of the retainer, as shown in the figure.

translational detent 2 en

If for the parameter Parameterization the value is set By geometry, then the block uses four areas to determine the shear force. The picture shows these areas.

translational detent 3

Since the ball has a spherical shape and the notch is symmetrical, the dependence of the horizontal force on the displacement is symmetrical relative to the origin.

The table describes the position of the ball, the contact angle, and the effect of the shear force for each area.

Area	Ball position and contact angle	Shear force
1	The ball is located outside the conical recess. The contact angle is vertical.	Only viscous damping and kinetic friction. The spring is not taken into account.
2	The ball enters the recess and comes into contact with its corner. The contact angle deviates from the vertical.	The effect of springs, viscous damping and kinetic friction. Maxima during the transition from region 2 to region 3.
3	The ball slides along the surface of the recess. The contact angle remains constant.	The force decreases as the spring is stretched until it reaches the value of the spring pre-tension force.
4	The ball moves from one side to the other. The contact angle changes direction.	The force changes direction. The width of the area of the shift direction change determines the smoothness of this switching.

Area

Ball position and contact angle

Shear force

The ball is located outside the conical recess. The contact angle is vertical.

Only viscous damping and kinetic friction. The spring is not taken into account.

The ball enters the recess and comes into contact with its corner. The contact angle deviates from the vertical.

The effect of springs, viscous damping and kinetic friction. Maxima during the transition from region 2 to region 3.

The ball slides along the surface of the recess. The contact angle remains constant.

The force decreases as the spring is stretched until it reaches the value of the spring pre-tension force.

The ball moves from one side to the other. The contact angle changes direction.

The force changes direction. The width of the area of the shift direction change determines the smoothness of this switching.

If for the parameter Parameterization the value is set By table lookup, then you can set an arbitrary function of the dependence of the shear force on the relative displacement. When creating such a feature, keep in mind the following recommendations.

conservation of energy

If you want to ensure the conservation of energy when using a locking device, then the total integral of the function of force dependence on relative displacement should be zero.

The performance of modeling

To stabilize the lock simulation, discontinuities in the force versus relative displacement function should be avoided. The most important requirement is the presence of an area of change in the direction of the shift of a non-zero width, similar to area 4 in geometric parameterization.

Assumptions and limitations

The model does not take inertia into account. If necessary, add inertia conditions from the outside to the R and C ports.
If you use parameterization based on the maximum force and width of the recess or parameterization according to the table, then kinetic friction does not depend on the normal force acting on the latch.

Ports

Conserving

# R — locking rod
translational mechanics

Details

Non-directional port connected to the locking pin.

Program usage name

rod_flange

# C — fastener body
translational mechanics

Details

Non-directional port connected to the fastener body.

Program usage name

case_flange

Parameters

Detent Characteristics

# Parameterization — parameterization of the lock
By peak force and notch width | By table lookup | By geometry

Details

Parameterization of the lock characteristics:

By peak force and notch width — specify the characteristics of the retainer using the maximum shear force and the width of the recess.
By table lookup — Determine the characteristics of the latch using a table based on the relative movement between the slider and the housing.
By geometry — determine the characteristics of the retainer using the geometry of the ball and recess and dynamics.

Values	`By peak force and notch width` \| `By table lookup` \| `By geometry`
Default value	`By peak force and notch width`
Program usage name	`parameterization`
Evaluatable	Yes

# Peak force — maximum shear force
N | kN | lb | mN | dyn | lbf

Details

The maximum shear force generated inside the retainer.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By peak force and notch width.

Units	`N` \| `kN` \| `lb` \| `mN` \| `dyn` \| `lbf`
Default value	`10.0 N`
Program usage name	`F_peak`
Evaluatable	Yes

# Notch width — the area of shear force
m | cm | ft | in | km | mi | mm | um | yd

Details

The width of the area where the shear force occurs.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By peak force and notch width.

Units	`m` \| `cm` \| `ft` \| `in` \| `km` \| `mi` \| `mm` \| `um` \| `yd`
Default value	`30.0 mm`
Program usage name	`notch_width`
Evaluatable	Yes

# Initial relative position — starting position
m | cm | ft | in | km | mi | mm | um | yd

Details

The relative position of the slider and the body at the beginning of the simulation.

Units	`m` \| `cm` \| `ft` \| `in` \| `km` \| `mi` \| `mm` \| `um` \| `yd`
Default value	`0.0 mm`
Program usage name	`delta_x_start`
Evaluatable	Yes

# Relative displacement vector — vector of relative displacement values
m | cm | ft | in | km | mi | mm | um | yd

Details

A vector of relative displacement values, the elements of which correspond to a vector of shear force values Force vector. These two vectors must be the same size. The movements should be listed in ascending order.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By table lookup.

Units	`m` \| `cm` \| `ft` \| `in` \| `km` \| `mi` \| `mm` \| `um` \| `yd`
Default value	`[-15.0, -12.3, -7.6, -1.1, 1.1, 7.6, 12.3, 15.0] mm`
Program usage name	`delta_x_vector`
Evaluatable	Yes

# Force vector — vector of shear forces
N | kN | lb | mN | dyn | lbf

Details

A vector of shear force values, the elements of which correspond to a vector of relative displacements Relative displacement vector.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By table lookup.

Units	`N` \| `kN` \| `lb` \| `mN` \| `dyn` \| `lbf`
Default value	`[0.0, 0.0, -8.365, -5.87, 5.87, 8.365, 0.0, 0.0] N`
Program usage name	`F_vector`
Evaluatable	Yes

# Interpolation method — the interpolation method
Linear | Smooth

Details

An interpolation method for approximating the output value when the input value is between two consecutive points in the table. Set as:

Linear – select this value for the lowest computational cost.
Smooth – select this option to get a continuous curve with continuous first-order derivatives.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By table lookup.

Values	`Linear` \| `Smooth`
Default value	`Linear`
Program usage name	`interpolation_method`
Evaluatable	Yes

# Ball diameter — ball diameter
m | cm | ft | in | km | mi | mm | um | yd

Details

The diameter of the cross-section of the ball.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By geometry.

Units	`m` \| `cm` \| `ft` \| `in` \| `km` \| `mi` \| `mm` \| `um` \| `yd`
Default value	`12.0 mm`
Program usage name	`ball_diameter`
Evaluatable	Yes

# Notch angle — recess angle
deg | rad | rev | mrad

Details

The full angle of the conical recess.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By geometry.

Units	`deg` \| `rad` \| `rev` \| `mrad`
Default value	`120.0 deg`
Program usage name	`notch_angle`
Evaluatable	Yes

# Notch depth — depth of excavation
m | cm | ft | in | km | mi | mm | um | yd

Details

The depth of the conical notch on the slider.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By geometry.

Units	`m` \| `cm` \| `ft` \| `in` \| `km` \| `mi` \| `mm` \| `um` \| `yd`
Default value	`4.5 mm`
Program usage name	`notch_depth`
Evaluatable	Yes

# Preload force — spring pre-tension force
N | kN | lb | mN | dyn | lbf

Details

The force for pre-tensioning the locking spring.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By geometry.

Units	`N` \| `kN` \| `lb` \| `mN` \| `dyn` \| `lbf`
Default value	`15.0 N`
Program usage name	`F_preload`
Evaluatable	Yes

# Spring stiffness — spring stiffness
N/m | lbf/ft | lbf/in

Details

The stiffness of the locking spring.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By geometry.

Units	`N/m` \| `lbf/ft` \| `lbf/in`
Default value	`3000.0 N/m`
Program usage name	`k`
Evaluatable	Yes

# Shear reversal region — length of the area of the shift direction change
m | cm | ft | in | km | mi | mm | um | yd

Details

The width of the area between the edges of the notch.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By geometry.

Units	`m` \| `cm` \| `ft` \| `in` \| `km` \| `mi` \| `mm` \| `um` \| `yd`
Default value	`0.1 mm`
Program usage name	`shear_reversal_region`
Evaluatable	Yes

Friction

# Viscous friction coefficient — coefficient of viscous friction
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)

Details

The coefficient of viscous friction at the contact of the ball with the recess.

Units	`kg/s` \| `N*s/m` \| `N/(m/s)` \| `lbf/(ft/s)` \| `lbf/(in/s)`
Default value	`0.1 N/(m/s)`
Program usage name	`viscous_coefficient`
Evaluatable	Yes

# Friction to peak force ratio — coefficient of kinetic friction

Details

Coefficient for calculating kinetic friction.

Kinetic friction is defined as the product of the coefficient of kinetic friction and the maximum shear force.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By peak force and notch width or By table lookup.

Default value	`0.01`
Program usage name	`friction_to_peak_force_ratio`
Evaluatable	Yes

# Friction velocity threshold — threshold value of the friction velocity
fpm | fps | kph | mph | m/s | cm/s | ft/s | in/s | km/s | mi/s | mm/s

Details

The relative velocity required to achieve maximum kinetic friction in the retainer.

Units	`fpm` \| `fps` \| `kph` \| `mph` \| `m/s` \| `cm/s` \| `ft/s` \| `in/s` \| `km/s` \| `mi/s` \| `mm/s`
Default value	`0.05 m/s`
Program usage name	`v_friction_threshold`
Evaluatable	Yes

# Kinetic friction coefficient — coefficient of kinetic friction

Details

Kinetic coefficient of friction for ball–groove contact.

Dependencies

To use this parameter, set for the parameter Parameterization meaning By geometry.

Default value	`0.1`
Program usage name	`kinetic_friction_coefficient`
Evaluatable	Yes