What Are Ergometers?

The use of the elasticity of metal to make an instrument marked with a scale to measure the force is called a "dynamometer". Force gauges come in a variety of different constructions, but the main part of them is a bent and resilient steel leaf or a helical spring. When an external force deforms the elastic steel sheet or spring, the pointer is driven to rotate by a transmission mechanism such as a lever, and the position where the pointer stops on the scale is the value of the external force.

Chinese name: Dynamometer
Nature: science

Category: physical
Belong to: instrument

Dynamometer definition

There are types such as grip dynamometers, and spring scales are the simplest type of dynamometer. Lift the object vertically with the dynamometer. When the spring dynamometer and the object are stationary, it indicates that the object is subject to a balance force, that is, gravity and pulling force are a pair of balancing forces with the same magnitude. The force of the dynamometer on the object is the same as the acting force and the reaction force, so the reading is the gravity of the measured object. According to F = k · X (Hook's law), the force is proportional to the spring extension. Coulomb torsion scale: The torsion of the suspension wire can provide a method for physicists to accurately measure small forces. The torsional moment is directly proportional to the twist angle of the suspension wire, proportional to the fourth power of the suspension wire diameter, and inversely proportional to the length of the suspension wire. The main part of a Coulomb torsion scale is a metal wire, which is fixed at the upper end and an object is suspended at the lower end. The object rotates under the action of an external force to twist the metal wire. After measuring the twist angle, the external force can be calculated according to the law of torsion.

Scales: The principle of scales is measured by force, but on the earth, in the reference frame (inertial reference frame) where the earth is considered immovable, the scale weighs out the "correct" result. Because the gravity acceleration is 9.8N / kg. If it is on the moon, it is not "correct" because the scale regards the acceleration of gravity as 9.8N / kg. In fact, the acceleration of gravity on the moon is much smaller than this.

Dynamometer law

Spring scale: mainly Hooke's theorem: F = k x.

The length of the spring is proportional to the external force. This ratio is the stubbornness of the spring.

Dynamometer Gallery (4 photos)

Number k.

Dynamometer strain gauge

Basic principles of creep compensation

Anchor cable dynamometer

The basic principle of the anchor cable dynamometer is to install a strain string sensor or force sensor with high stability and sensitivity on the pressure-bearing cylinder. It is generally considered that the string sensor with mature technology has better zero point stability and more stability than the strain gauge. Strong anti-interference ability, meanwhile its signal output is frequency instead of voltage. Frequency signals can be transmitted over long distances without significant attenuation due to cable resistance and contact resistance changes. On the other hand, although the use of string instruments has the above-mentioned series of advantages, because the design and processing of string anchor dynamometers involve many unique technical problems, only a few well-known string instrument manufacturers in the world can produce real quality. Excellent long-term reliable string anchor cable dynamometer.

A plurality of string sensors are uniformly arranged along the periphery of the hollow pressure cylinder made of high-strength alloy steel, and the load acting on the pressure cylinder can be directly measured by the string sensors fixed on the cylinder.

The use of multiple sensors can reduce or eliminate the effects of uneven or eccentric loads. In order to ensure the reliable fixing of the sensor, spot welding or other techniques are used to firmly weld the sensor to the barrel. A thermal thermometer is also provided in the cylinder to measure the anchor cable dynamometer and the ambient temperature on site. In order to adapt to the harsh conditions on site, the overall sealing technology is adopted, so that the anchor cable dynamometer can work normally under 2MPa water pressure.

Digital dynamometer

Digital dynamometers are widely used in various industries such as pharmaceuticals, cosmetics, food, packaging, automotive, electrical, electronics, and machinery.

Digital dynamometer (3 photos)

. It is an indispensable force measuring tool in product manufacturing, quality management and research and development. There is a new type of dynamometer with perfect data management function. It can be connected to a computer through a USB interface, and can perform 1000 peaks / second fast peak measurement. You can set upper and lower limits to determine whether the product is qualified. It can also be used in conjunction with the dynamometer bracket to obtain high-precision measurements.

Dynamometer electronic scale

Dynamometer Introduction

Weighing articles are converted into analog signals of voltage or current by weight sensors mounted on the mechanism. After being amplified and filtered, they are converted by A / D processors into digital signals. The digital signals are calculated by the central processing unit (CPU). Processing, and peripheral functions and various interface circuits are also connected to the CPU application, and finally displayed digitally by the display screen.

Force gauge steel string reinforced force gauge

The working principle is that the resonance frequency of a tensioned steel string is proportional to the strain or tension of the steel string. This basic relationship can be used to measure various physical quantities such as strain, load, force, pressure, temperature, and tilt. . The advantage of vibrating wire sensors over ordinary sensors is that the output of the sensor is frequency rather than voltage. Frequency can be transmitted through long cables (> 2000 meters) without significant signal attenuation caused by changes in wire resistance, water immersion, temperature fluctuations, contact resistance or insulation changes. In addition, coupled with the design and manufacture of Gicon's unique process, Gicon's vibrating wire sensors have excellent long-term stability, which is especially suitable for long-term monitoring in harsh environments.

Steel string reinforced dynamometer (2 photos)

Dynamometer earth pressure box

The soil is composed of tiny particles, and there are a lot of pores in the soil, which make it have two basic conditions for the existence of micro-cracks in the soil. It also meets the assumption that fracture mechanics believes that micro-cracks exist in the material. Under certain stress conditions, the structural connection between the soil particles gradually breaks along the weak links, and the micro-fissures gradually develop into macro-scale cracks, eventually leading to the failure of the soil mass. According to the theory of fracture mechanics, the fracture failure of an object can be divided into three basic stress modes: (1) an open-type crack (type I), that is, normal stress and the crack surface are perpendicular, and (2) a sliding-type crack (type ) in In the case where the component surface or the specimen is sheared, if the shear stress is parallel to the crack surface but its action direction is perpendicular to the crack surface, the upper and lower sides of the crack will relatively slide and expand. (3) Tear-type crack (type ), the shear stress is parallel to the crack surface, and under the action of shear stress, the upper and lower planes of the crack tear and expand.

Dynamometer pore water pressure gauge

The working principle is that the pressurized water in the soil pores is collected into the pressure-bearing cavity through the permeable stone and acts on the pressure-bearing diaphragm. Deflection in the center of the diaphragm causes stress in the steel string.