| IABG leads in the development and fine-tuning of test procedures for car springs. We develop and operate test benches both for mechanical testing of springs, optionally in corrosive media, and for preconditioning through stone chip simulation and corrosion using salt spray and fog and regulated climates.
IABG spring test benches for spring elements stand out through realistic simulation of deformations and environmental conditions. They are low maintenance and feature short set-up and adjustment times and very low power consumption. IABG is the largest test laboratory in Europe for this type of tests.
We have decades of experience in developing suitable test procedures for statistically backed-up fatigue analyses and in the planning, implementation and statistical evaluation of such tests. Many renowned manufacturers of springs and the majority of German car makers are our customers.
Rotating bending testing machine
Test bench for determining the fatigue strength of round bars and tubes as used in the production of suspension springs and stabiliser bars for automobiles.
Technical specification
- Test items: machined or unmachined cylindrical bars or tubes (also for stepped shafts).
- Bar/tube diameter: d = 10 to 30 mm
- Bar/tube length: L = 60 x d + 140 mm (or special lengths)
- Test frequency: f = 5 to 50 Hz (variable)
- Power consumption: < 1 kW
- Properties: no outgoing vibrations, very quiet
- Weight: approx. 1000 kg
- Dimensions: L = 2600 mm, W = 1000 mm, H = 1500 mm
- Loading: load input via crowned, non-wearing plastic rings
- Load (stress) and strain measurement
Advantages compared with existing test machines
- No clamping of the round bars necessary (fits all diameters in specified range).
- Surface under tension stress is untouched.
- Large and therefore representative material volume.
- Short set-up and changeover times (approx. 5 min.).
Purpose of the rotating bending tests
- Comparison of fatigue strength before machining of the raw material into the end product.
- Material optimisation (e.g. type of material, heat treatment, shot blasting parameters, reduction of variance etc.).
- Determination of fractures, inclusions and similar flaws in materials.
- Assessment of surface quality.
- Quality control.
Typical results
- Fatigue strength in range.
- Fatigue endurance limit.
- Dispersion along the Wöhler line.
- Fractography (see photos below) of shot-blasted rods with a diameter of 22 mm made of spring steel.
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Spring coil test bench
Test bench for determining the fatigue strength of individual spring coils
- Technical specification
- Test items: two spring coils from cylindrical car axle springs
- Clamping in the machine: between tips
- Wire diameter: d < 22 mm
- Spring diameter: Dm = 40 to 320 mm
- Test frequency:
- Low speed: f = 0.2 to 1.5 Hz
- High speed: f = 8 to 40 Hz
- Environmental conditions: normal laboratory environment or salt spray.
Aim of the tests
Comparative testing of fatigue strength. The type of test described below cannot be made on complete springs, at least not cost-effectively and at short notice. In addition, coil tests of this type provide approx. 40% higher stress than in the testing of the associated springs. This permits greater mean stress variations.
Some of the test options:
- Testing of surface protection, the influence of pre-corrosion and corrosion during the test (realistic test conditions).
- Testing the influence of the test frequency on the service life under corrosion.
- Testing of the influence of the material, thermal treatment, shot blasting, surface quality and surface protection coating etc.
- Testing of the influence of mean stress (vehicle loading).
- Wöhler lines.
- Dispersion in time and frequency range
- Testing for predicting service life (damage accumulation) under collective loading.
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Stone impact simulator
Test bench for causing defined damage to the surface protection coating of vehicle components by stone impact.
Technical specification
- Components: Axle springs, stabiliser bars, other chassis and under body components, paintwork of body sheet, wear of glass components.
- Shot material: Grit, pebbles, gravel up to 15 mm diameter, sand, globes of all types of material.
Speed of discharge: v = 20 to 140 km/h, continuously adjustable.
- The discharge unit is movable over the complete length of the test bench and can also be adjusted vertically.
- Rotation frequency: f = 0.5 or 1.0 Hz
- Amount of the shot material discharged per time unit is continuously adjustable.
Advantages compared with the standard units that use compressed air
- The speed of discharge of the individual particles of the shot material is independent of their weight, size and shape.
- This permits you to simply reproduce test conditions everywhere.
- Maintenance-free and reliable.
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Resonance machine for testing the fatigue strength of resilient components in normal laboratory atmosphere
Technical specification
- Components to be tested: Springs of all kinds with parallel and circular deformation without corrosion impact
- Maximum load allowed for each of the two test positions: Fmax = 40kN
- Number of springs that can be tested simultaneously: 2, 4, … limited by Fmax
- Stroke (path-controlled): S = 10 to 250 mm
- Maximum spring length: Lo = 600 mm
- Test frequency: fo = 0.47 x sqrt (n x R) [Hz]
n = number of springs to be tested simultaneously
R = spring constant [N/mm]
fo = 2 to 25 Hz
- Measurement of spring force and spring length
Purpose of the resonance spring tests
- Time-saving, cost-effective determination of the fatigue strength of springs in a normal laboratory atmosphere.
- Simultaneous testing of multiple spring elements (including tension springs!). The number of spring elements that can be tested simultaneously is limited only by the maximum load allowed and the available set-up space.
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Resonance test bench for large coil springs
Resonance test bench for testing large spring components (or a large number of small components).
Technical specification
- Components to be tested: springs of all kinds with parallel deformation
- Type of load: constant or variable amplitudes (collective loading)
- Maximum load allowed for each of the two test positions: Fmax = 200 kN
- Number of springs that can be tested simultaneously: limited by Fmax
- Stroke (path-controlled): S = 10 to 400 mm
- Maximum spring length: Lo = 1000 mm
- Test frequency: fo = 0.19 ... 0.28 x sqrt (n x R) [Hz]
n = number of springs to be tested simultaneously
R = spring constant [N/mm]
fo = 2 to 20 Hz
Purpose of the tests
- Time-saving, cost-effective determination of the service life of spring elements of all kinds.
- Possibility of vibrating multiple springs simultaneously, for example:
100 car engine valve springs
50 car clutch springs
30 valve springs of large, stationary diesel engines
20 car axle springs
2 railway springs
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Resonance test bench for stabiliser bars
Test bench for determining the fatigue strength of stabiliser bars of cars.
Technical specification
- Test items: all kinds of stabiliser bars for passenger cars; one or two bars simultaneously
- Bar diameter: d = 10 to 42 mm
- Bar length: L ≤ 1800 mm,
- Test frequency: f = 10 to 25 Hz
- Type of load: constant and randomly variable amplitudes (collective tests), purely alternating loading (R = -1).
Advantages compared with the standard eccentric test benches
- 5 to 10 times faster.
- Short set-up times.
- Simple, fast, reliable, documentable.
- Low power consumption (approx. 2 kW).
- Collective tests possible (randomly mixed short blocks).
- Universal application, e.g. also for tests with rubber bearings and complete chassis.
Purpose of the resonance tests on stabiliser bars
- In the development phase
- Production release tests.
- Determination of procedures for increasing fatigue strength.
- Testing and optimising of production parameters relating to fatigue strength.
- Examination of problems of damage accumulation through Wöhler and fatigue strength tests.
- During the production phase
- Quality monitoring in accordance with the relevant requirements.
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Corrosion chambers for storing test items in corrosive media
More information is available under Corrosion.
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