Details

Pressure impulse + external load (dynamic shear) — endurance validation with traceable, repeatable waveforms
Hydraulic and fluid-power components almost never fail because a system once hit a pressure number. They fail because the system keeps hitting that number for months, with fast transients that drive fatigue, and with constant mechanical “disturbance” from routing, vibration, clamping, and movement. A coupling that is perfectly dry on day one can begin to seep after a few hundred thousand cycles because the pressure pulse is breathing the assembly, while external side-load is creating micro-slip at the joint, and temperature drift is quietly changing stiffness and seal behavior. That’s where real leakage is born—slowly, predictably, and only visible when you run a controlled endurance test long enough.
This test rig is built for exactly that reality. It generates repeatable pressure impulse waveforms and repeatable dynamic shear (external load) waveforms—independently or together—while continuously logging cycle snapshots and long-run trends (peak/base/rise time and load peaks). The end result is not just a pass/fail; it’s hard evidence: “Here is the waveform, here is the stability, and here is exactly when and how the component started to degrade.”

What this system validates (what the test proves)
Typical Units Under Test (UUTs)
• Hose assemblies and couplings
• Pipe/tube sections, adaptors, fittings, connectors
• Filters, valve bodies, manifolds
• Small pressure-containing assemblies and similar components

What you learn from endurance testing
• Fatigue life under repeated pressure transients
• Leak integrity over long cycling (including progressive leakage growth)
• Waveform stability over time:
  ▹ peak pressure drift (or lack of drift)
  ▹ base pressure drift (or lack of drift)
  ▹ rise time consistency (transient repeatability)
  ▹ Load Channel A peak stability
  ▹ Load Channel B peak stability
• Real failure mode replication under combined pressure + external loading (often where field failures hide)

Test Methodology 1: Pressure Impulse Endurance Test
(Impulse-only endurance on single-joint / impulse specimens)

What the test does
Pressure impulse endurance testing repeatedly drives the UUT through a controlled pressure-time profile—typically a fast ramp to a target peak, a controlled decay, and a repeat cycle—at a defined cycle rate for a high number of cycles. The goal is not “reach pressure once”; the goal is “hit the same curve reliably, every time, for lakhs of cycles.”

In practical endurance testing, the UUT and the fluid behave like a spring-damper system. If air is present, if temperature changes, or if leakage begins, the waveform will drift: rise time changes, peak pressure becomes unstable, or baseline shifts. That drift is not a nuisance—it is often your first indicator of degradation. This is why the rig measures and controls the waveform continuously, and why the plots generated during the run are so valuable.

What the rig controls and why it matters
• Peak pressure control: Ensures fatigue energy per cycle is consistent. If peak drifts down, you may under-test; if it drifts up, you may over-stress and get meaningless failures.
• Base pressure control: A drifting baseline can indicate compressibility changes, trapped air release, or leakage evolution.
• Rise time control: Rise-time drift can indicate air release, increasing leakage, or dynamic changes in the UUT’s stiffness.

What the rig records during the run
• Cycle snapshot graphs (pressure vs time) at selected cycles—typically near end-of-run as proof of repeatability
• Peak pressure trend across cycles (stability evidence)
• Base pressure trend across cycles (baseline evidence)
• Rise time trend across cycles (dynamic response evidence)

Failure behaviors this test exposes clearly
• Progressive leakage growth: initially stable, then a gradual shift in baseline/peak stability before visible leakage
• Fatigue cracking: late-cycle leakage onset with stable waveform until the crack reaches a threshold
• Joint/seal deterioration: increasing scatter in peak/base, rise-time drift, and eventual inability to stay within envelope
• Loss of waveform compliance: the control system “works harder” and eventually cannot maintain the same curve—often an early warning before catastrophic failure


Cycle No.999
Graph Pressure impulse waveform at Cycle 999 — rise, peak hold and decay remain within the defined envelope, demonstrating late-cycle repeatability.



Cycle No.1000 
Graph Pressure impulse waveform at Cycle 1000 — confirms cycle-to-cycle repeatability of peak level and transient response at end-of-run.



Pressure Peak Graph 
Peak pressure vs cycle — shows closed-loop peak stability across the endurance run (drift and scatter monitoring).



Base Pressure Graph 
Base pressure vs cycle — verifies baseline stability and highlights any gradual offset that may indicate compressibility change or developing leakage.



Rise Time Graph 
Rise time vs cycle — tracks transient consistency; rising rise-time scatter or drift is an early indicator of system/UUT dynamic change.


Test Methodology 2: Dynamic Shear Endurance Test
(Internal pressure + alternating external load on two joints; Load Channel A and B)

What the test does
Dynamic shear endurance testing is designed to replicate the most failure-prone real-world condition: the component is pressurized while its joint is simultaneously subjected to external mechanical stress—the kind introduced by installation constraints, routing forces, vibration, movement, and bending.

Instead of treating the assembly as “a static pipe,” this test treats it as it exists in a machine: loaded, moving (micro-moving), and pressurized.

Alternating joint loading (Channel A / Channel B)
Dynamic shear specimens typically include two joints/couplings under test. The rig runs a controlled sequence where:
1. Internal pressure is raised and held stable at the defined level
2. External load is applied to Joint A (Load Channel A): ramp → reach peak → hold (dwell) → unload
3. External load is applied to Joint B (Load Channel B): ramp → reach peak → hold (dwell) → unload
4. The sequence repeats at a defined cycle rate for the full endurance life
This alternating strategy is important because many assemblies have multiple couplings and do not fail uniformly—one joint may weaken earlier depending on micro-alignment, clamp influence, or manufacturing variability.

What the rig controls and why it matters
• Pressure stability during load: Pressure must not collapse or drift while the load is held, otherwise you are not testing combined stress properly.
• Load peak repeatability: Load peaks must remain stable cycle after cycle; drift indicates instability or a changing mechanical condition.
• Dwell behavior: Holding load at peak is where seal micro-slip damage often accumulates; dwell consistency matters.
• Channel balance: Tracking Load A and Load B separately helps identify asymmetry and joint-specific degradation.

What the rig records during the run
• Cycle snapshot graphs showing the full composite waveform (pressure + alternating loads)
• Pressure peak trend vs cycle (proves stable pressurization while loading)
• Load A peak trend vs cycle
• Load B peak trend vs cycle

Failure behaviors this test exposes clearly
• Leakage only under load: component passes impulse-only, but leaks once external shear is applied
• Fretting-driven leakage: progressive seal/interface damage due to micro-slip while pressurized
• Joint fatigue under combined stress: reinforcement and fitting fatigue driven by pressure + mechanical loading
• Mechanical compliance change: load peaks start shifting or scatter increases as stiffness changes—often a precursor to failure


Cycle No.498 Graph 
Dynamic shear composite waveform at Cycle 498 — internal pressure maintained while external shear load is applied sequentially to Load Channel A and B (dwell + unload visible).



Cycle No.499 Graph 
Dynamic shear composite waveform at Cycle 499 — confirms repeatability of pressure plateau and alternating load sequence across consecutive cycles.



Cycle No.500 Graph 
Dynamic shear composite waveform at Cycle 500 — end-of-run snapshot demonstrating stable pressure during peak load dwells and consistent channel timing.



Pressure Peak Graph 
(Dynamic Shear) Peak internal pressure vs cycle during dynamic shear — verifies pressure stability under combined pressurization + external loading.



Load A Peak Graph 
Load Channel A peak vs cycle — demonstrates closed-loop load repeatability and stability band adherence for joint A.



Load B Peak Graph 
Load Channel B peak vs cycle — demonstrates closed-loop load repeatability and stability band adherence for joint B.


Combined / Simultaneous Testing Capability
(Impulse + shear together, where configured)
For advanced validation programs, the rig can be configured to run pressure impulse and dynamic shear in coordinated operation—either to increase throughput or to apply combined stress exposure across multiple specimens. This is useful when the target failure mode requires both high-cycle pressure fatigue and mechanically induced joint damage.

What the delivered test evidence looks like
This rig produces “qualification-style” evidence, not just cycle counts:
• Representative cycle waveform pages that show repeatability (e.g., cycle 498/499/500, or 999/1000)
• Long-run trend graphs that prove stability:
  ▹ peak pressure vs cycle
  ▹ base pressure vs cycle
  ▹ rise time vs cycle
  ▹ load A peak vs cycle
  ▹ load B peak vs cycle
• Clear fault/event behavior (when configured): alarms and safe stops if limits are exceeded

Key capabilities (typical configuration highlights)
• Pressure impulse rise rate up to ~100 bar/s
• Load rise rate up to ~2300 lb/s
• Tight peak stability bands for long endurance runs (pressure and load)
• Continuous graphing across lakhs of cycles
• Multi-specimen and multi-program flexibility (fixture / manifold / recipe dependent)

Technical Specifications (typical configuration)   

  

    
Parameter
    
Specification
  
  

    
Test types
    
Pressure impulse endurance, dynamic shear endurance (pressure + alternating external load), combined testing where configured
  
  

    
Max test pressure (typical configuration)
    
Up to 20 bar
  
  

    
Max impulse pressure (typical configuration)
    
Up to 16 bar
  
  

    
Max proof pressure (typical configuration)
    
Up to 20 bar
  
  

    
Max external load (dynamic shear)
    
Up to 1000 lb
  
  

    
Pressure rise rate
    
Up to 100 bar/sec
  
  

    
Load rise rate
    
Up to 2300 lb/sec
  
  

    
Endurance duty
    
Designed for lakhs of cycles (typical programs around 330,000 cycles)
  
  

    
Data output
    
Cycle waveform snapshots + trend graphs (peak/base/rise time and load peaks)
  
  

    
Control approach
    
Closed-loop control for pressure and load with automatic correction to maintain waveform stability
  
  

    
Utilities (typical)
    
3-phase supply for hydraulics + single-phase supply for DAQ/control (final varies by configuration)
  
  

    
Footprint / weight
    
Heavy-duty industrial station; dimensions and mass depend on enclosure, fixtures, and number of stations