Polycarbonate strength is not one interchangeable number. Tensile data describe a standardized specimen in tension; flexural data describe a supported specimen in bending; falling-weight impact data describe a defined impact event. An installed guard, roof panel or enclosure also depends on grade, thickness, temperature, span, edge support, holes, loading rate and service time.
Choose the strength property
Begin with the way the component can fail. A material with suitable tensile data may still deflect too far as a wide panel. A sheet that survives one impact method may not satisfy a different striker, support or temperature. A long-term clamp load raises creep questions that a short coupon test does not answer.
| Design question | Evidence to request | Evidence cannot prove by itself |
|---|---|---|
| Will a tie or narrow part yield in tension? | Grade-specific tensile method, conditioning and stress-strain result. | Impact resistance or installed panel capacity. |
| How will a panel behave between supports? | Flexural data plus a calculation using the actual span and edge condition. | Capacity of a panel with different holes, frame or temperature. |
| What happens under a sudden local strike? | Impact method with striker, energy, support, thickness and test temperature. | Response to an unmatched projectile or safety threat. |
| Will shape change under sustained load? | Creep or stress-relaxation evidence at relevant time and temperature. | Long-term performance from a short room-temperature test. |
Use the property that represents the load case. Avoid generic “times stronger than glass” comparisons: they omit the failure mode, specimen and method and do not size the finished part.
Control the test conditions
ASTM D638 covers tensile properties of plastics under defined specimen preparation, conditioning and test speed. ASTM D790 covers flexural properties using a defined beam and loading arrangement. ASTM F736 covers falling-weight impact resistance of monolithic polycarbonate under specified conditions and warns against direct comparison across unlike specimen types or test conditions.
- manufacturer, grade, colour, sheet structure and production form;
- nominal and measured specimen thickness;
- test method, edition, specimen type and preparation route;
- temperature, conditioning, loading rate and support geometry;
- number of specimens, result definition and acceptance rule;
- coating, UV layer or treated face and its test orientation.
Check the complete assembly
A data sheet is a material-screening tool. It does not include the project’s unsupported span, frame stiffness, fastener preload, holes, sharp corners, sealants, cleaning chemicals, outdoor aging or installation workmanship. Those details can govern the first failure.
For a machine guard, define the credible impact, required containment, safe distance, attachment and replacement rule. For a roof or canopy, use the project wind, snow, maintenance and drainage loads with the actual support pattern. The responsible engineer or safety professional must approve the assembly.
Thickness does not work alone
Increasing thickness generally changes stiffness and impact response, but the relationship is not a universal multiplier. A thicker panel with a longer span or weaker edge capture may perform worse than a thinner panel in a better frame. Ask for a calculation or test that uses the actual geometry.
Prototype the critical detail
- Freeze the offered grade, thickness, colour, coating and fabrication route.
- Build the least forgiving span, corner, hole or fixing zone.
- Apply a test that represents the real load direction and support.
- Record setup, environment, measurements, damage and acceptance rule.
- Retain the approved sample and report with the drawing revision.
Failure modes worth investigating
- Crack from a hole: stress concentration, machining damage or chemical exposure may combine.
- Excessive deflection: stiffness and span can control serviceability before fracture.
- Cold or fast event: room-temperature data may not represent service.
- Slow distortion: sustained stress and heat require time-dependent evidence.
What SinoPlastix needs for a strength review
Send the application, drawing, support condition, load type, environment, required test method, acceptance threshold and consequence of failure. SinoPlastix can identify an offered sheet construction and review manufacturability; that does not replace structural design, machine-safety validation or security certification.
Primary method references
- ASTM D638 — tensile properties of plastics
- ASTM D790 — flexural properties of plastics
- ASTM F736 — falling-weight impact of monolithic polycarbonate sheet
Scope: This page explains evidence and supplier inputs. It is not a load calculation, test report or certification for a finished installation.