RCF HDL15-AS Owner's Manual page 9

WARNING: Each cabinet support the full load of the part of the system below. It is very
important that each single cabinet of the system is properly checked.
The suspension system is designed to have a proper Safety Factors (configuration
dependent). Using the "RCF Shape Designer" software it is very easy to understand safety
factors and limits for each specific configuration. To better comprehend in which safety
range the mechanics are working a simple introduction is needed: HDL15-AS mechanics
are built with certified UNI EN 10025-95 S 235 JR and S 355 JR Steel. RCF prediction
software calculates forces on every single stressed part of the assembly and shows the
minimum safety factor for every link.
S 235 JR is a structural steel and S 355 has a stress-strain (or equivalent Force-Deformation)
curve like the following.
The curve is characterized by two critical points: the Break Point and the Yield Point. The
tensile ultimate stress is simply the maximum stress attained. Ultimate tensile stress is
commonly used as a criterion of the strength of the material for structural design, but it
should be recognized that other strength properties may often be more important. One
of these is for sure the Yield Strength. Stress-strain diagram of S 235 JR exhibit a sharp
break at a stress below the ultimate strength. At this critical stress, the material elongates
considerably with no apparent change in stress. The stress at which this occurs is referred
to as the yield point.
Permanent deformation may be detrimental, and the industry adopted 0.2% plastic strain
as an arbitrary limit that is considered acceptable by all regulatory agencies. For tension
and compression, the corresponding stress at this offset strain is defined as the yield.
S 355 J and S 235 JR characteristic values are R=360 [N/mm2] and R=510 [N/mm2] for
Ultimate Strength and Rp0.2=235 [N/mm2] and Rp0.2=355 [N/mm2] for Yield Strength. In
our prediction software the Safety Factors are calculated considering the Maximum Stress
Limit equal to the Yield Strength, according with many international standards and rules.
The resulting Safety Factor is the minimum of all the calculated safety factors, for each link
or pin.
This is where you are working with a SF=4:
Depending on local safety regulation and on situation the required safety factor can vary.
It is responsibility of the owner or rigger to make sure that the system is properly rigged
in accordance with Country and local laws and regulations. The "RCF Shape Designer"
software gives detailed information of the safety factor for each specific configuration.
The safety factor is the result of the forces acting on fly bar's and system's front and rear
links and pins and depends on many variables:
- number of cabinets;
- fly bar angles;
- angles from cabinets to cabinets. If one of the cited variables change the safety factor
MUST BE recalculated using the software before rigging the system.
In case the fly bar is picked up from 2 motors make sure that the fly bar angle is correct. An
angle different from the angle used in the prediction software can be potentially dangerous.
Never allow persons to stay or pass under the system during the installation process.
When the fly bar is particularly tilted or the array is very curved the centre of gravity can
move out from the rear links. In this case the front links are in compression and the rear
links are supporting the total weight of the system plus the front compression. Always
check very carefully with the "RCF Shape Designer" software all this kind of situations
(even with a small number of cabinets).
THE MAXIMUM NUMBER OF SPEAKERS THAT MAY BE SUSPENDED USING
THE HDL10-A FRAME IS:
n° 16 HDL10-A;
n° 8 HDL15-AS;
n° 4 HDL 15-AS + 8 (EIGHT) HDL 10-A USING ACCESSORY LINK BAR HDL10-HDL15-AS.
WARNING
"RCF SHAPE DESIGNER"
SOFTWARE AND SAFETY
FACTOR
N/mm
2
Ultimate
Strength
Yield
Strength
SF = 4
Working
Conditions
N/mm
2
Ultimate
Strength
Yield
Strength
SF = 4
Working
Conditions
MAXIMUM ARRAY SIzE
%
%
9