ANSYS Mechanical APDL

A Post 26 Primer: Post Processing over Multiple Time/Load Steps in Mechanical APDL

Eric Miller Co-Owner Principal, Simulation and Business Technologies 04/12/2012 PADT, Inc.

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Agenda • Note: This presentation is being recorded • • • • • • •

Introductions Fundamentals Defining Variables Viewing Variables Calculating Other POST26 Tools Suggestions and Recommendations

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Introductions

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Upcoming Webinars • Upcoming Webinars – – – –

– – – – –

•

Feb 9, 2012 - 12:00 MST Working Directly with Nodes and Elements in ANSYS Mechanical Feb 23, 2012 - 12:00 MST Assembly Meshing in ANSYS R14 CANCELED March 8, 2012 - 12:00 MST Intro to Workbench Framework Scripting - Controlling projects, materials, and solution execution with python March 22, 2012 - 12:00 MST Mastering the Remote Solver Manager (RSM) at R14

April 12, 2012 – 12:00 MST A POST26 Primer: Post Processing over Multiple Time/Load Steps in Mechanical APDL April 26, 2012 – 12:00 MST A Constraint Equation Primer: How to Tie Degrees of Freedom Together May 10, 2012 – 12:00 MST Optimization with ANSYS DesignXplorer at R14 May 24, 2012 – 12:00 MST Modeling Moisture Diffusion in ANSYS Summer Break: June & July (maybe August)

Primers are new: – Oriented towards newer users or Workbench users who may not have experience with some of the fundamentals in the ANSYS Mechanical APDL solver

•

See upcoming and past webinars at: – padtincevents.webex.com • Click on ANSYS Webinar Series DX R13: 02/17/2011 4

About PADT • PADT is an Engineering Services Company – Mechanical Engineering – 18 Years of Growth and Happy customers – 70’ish Employees

• 3 Business Areas – CAE Sales & Services • Consulting, Training, Sales, Support

– Product Development – Rapid Prototyping & Manufacturing

• Learn More: www.PADTINC.com

We Make Innovation Work DX R13: 02/17/2011 5

Cube HVPC Systems • Balance between speed and cost – Mini-Cluster 96 Cores / 512 GB RAM / 6 TB Disk Mobile Rack / UPS / Monitor / Keyboard $34,900 – Compute Server 32 Cores / 256 GB RAM / 3 TB Disk $14,250 – Simulation Workstation (Intel) 12 Cores / 96 GB RAM / 3 TB Disk $11,750 – Simulation Workstation (AMD) 12 Cores / 64 GB RAM / 3 TB Disk $6,300

• www.CUBE-HVPC.com

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PeDAL – The APDL Editor • • • • • • • •

Side-by-side editor and help viewer layout. Instant help on any documented APDL command by pressing F1. Full syntax highlighting for ANSYS v12 Mechanical APDL. Auto-complete drop downs for APDL Commands. APDL Command argument hints while typing commands. Search ANSYS help phrases and keywords. Multiple tabs for the editor and html viewer. Full capability web browser built in allows for rich web experience and web searches.

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Connect with PADT Facebook: facebook.com/padtinc

Email Subscriptions:

Twitter: #padtinc

Web: www.PADTINC.com

LinkedIn: Search on PADT, Inc.

ANSYS User Blog: padtinc.com/focus

www.padtinc.com/epubs

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Fundamentals

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Assumptions • You know the basics of MAPDL • You are not an MAPDL expert or guru – Need reminders on where some of the commands are

• That you will be accessing this via the MAPDL GUI, APDL macros, and code snippets in Workbench

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ANSYS Results • The ANSYS RST file stores results at various points – A point can be at a given time in a transient run or it can be a location on a load curve for a static run – Not necessarily every point that a solution is calculated at • User determines how often results are saved

– Each record has a time, load step, and sub step associated with it – Static or Transient, even modal results are stored the same way • Header and analysis type tell you what type of solution you have

• Do a SET,LIST to see what is in the file • Results are stored by node or element – DOF stuff by node – Stresses/Strains/etc… by element at each corner node – So to get at Stress/Strains/etc you must • Average over an element • Un-averaged for a corner node • Average over all elements attached to a node DX R13: 02/17/2011 11

Conventions/Words • We will refer to a given loadstep/substep, time point, or frequency as a “point” • Solution set is the collection of result solutions stored in the RST file. It is made up of solution points. • The “database” is not the *.db file. – It is the model and result information currently stored in memory

• An array is an APDL parameter of type array – A vector you can stick stuff in

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POST1 vs. POST26 • POST1, the general post processor – It looks at results across the whole model at a given point • LS/SS, Time, or Freq

– Use it to make contour plots, animations, list results at a given point – SET,LS,SS,FACT,KIMG,TIME to store a given point in the database

• POST26, the Time History Post Processor – Looks at a result value on a node or element over the solution set – Instead of loading all the results at a point into the database, it stores the results over the solution set for user specified nodes or elements – No model plots, just lists and graphs (usually vs. time) – Allows complex calculations on results

• You can do what POST26 does in POST1 with do loops – But every step loads all results – slow – POST26 “skips” through the file - fast

set,1,1 dim,myux,,nmstp *do,i,1,nmstp *get,myux(i),node,mynode,u,x set,next *enddo

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Getting into POST26 • /post26 – Required, commands are filtered

• Click on TimeHist PostPro in Main Menu

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Its all About Variables • A table of a result item at a location in the model vs time or frequency • Not an APDL parameter – But you can push one into an array

• You tell POST26 what variables you want to create • Whole set of commands for defining, modifying, mathamatizing, and controlling variables • Also a GUI tool to build the commands

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Our Test Model • Infamous “Tower of Test” – Transient, large deflection – Move base in UX (time,ux): • • • • •

0,0 .1,1 .2,5 .3,0 1,0

• Will post on blog

finish /clear /prep7 blc4,-1,-1,2,2,60 et,1,185 mptemp,1,70 mpdata,ex,1,1,20e6 mpdata,nuxy,1,1,.23 mpdata,dens,1,1,.001 alphad,5 esize,.9 vmesh,all /view,1,1,1,1 /vup,1,z eplot

nsel,s,loc,z,0 cm,nbt,node nsel,all d,nbt,uy,0 d,nbt,uz,0 d,nbt,ux,1 time,.1 antype,4 trnopt,full lumpm,0 nlgeom,1 kbc,0 timint,1 nsubst,40,40,40 outres,all,1 lswrite,1 d,nbt,ux,5 time,.2 lswrite,2 d,nbt,ux,0 time,.3 lswrite,3 time,2 lswrite,4 /solu lssolve ,1,4 finish /post1 plnsol,u,sum /POST26 FILE,'p26','rst','.' /UI,COLL,1 NUMVAR,200 SOLU,191,NCMIT STORE,MERGE FILLDATA,191,,,,1,1 REALVAR,191,191 !* NSOL,2,18,U,X, UX_2 STORE,MERGE XVAR,1 PLVAR,2

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Defining Variables

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Defining Variables • You have to tell POST26 what information you want and how you want it: – Node/Element, Where in an element, What type of result, How to average, etc…

• Each variable has a unique variable number – You access the variable with this number for operations/plotting/etc… – You can also give it a name: Label only

• Use: – ANSOL, NSOL, ESOL, EDREAD, RFORCE, JSOL, GSSOL, GAPF, SOLU

• Control with: – FORCE, LAYERP26, SHELL, CFACT, TVAR

• Or use the Tool • NOTE: Time or Freq automatically created and is Var=1 DX R13: 02/17/2011 18

Two Step Process • Define the variables with variable definition commands • Store them in the database • Separate Store for efficiency – Reads all the variables in at once

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Time History Variable Tool • When you enter POST26 in the GUI, it comes up – Or click “TimeHist Postpro->Variable Viewer”

• Even if you are doing scripting, use the GUI to figure it out

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Defining Variables in the Tool • Click the Plus Sign • Pick from list – It handles all the options/different commands for you

• Pick or give number of node/element • Example: Reaction Force on Bottom Node, in X – RFORCE,2,4,F,X, FX_2

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More on Tool • Icons from Left to Right: – ADD | Delete | Graph | List | Properties | Import | Save | Overlay | Clear | Refresh

• Variable list shows all the stored variables with name, node/element, what it is, min/max – Note that VAR number is not shown… count or do a STAT

• If you are not using the calculator, it gets in the way – Collapse and expand Variable list

• Automatically does a Store

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Variable Store Commands: Common • ANSOL, NVAR, NODE, Item, Comp, Name, Mat, Real, Ename – Average Nodal Data (stress/strain) • You can tell it what material/real/element type to use when node is on boundary • Uses RSYS • Uses AVPRIN to tell it how to average if default (average components then derive) is not OK

• ESOL, NVAR, ELEM, NODE, Item, Comp, Name – Element data (Stress/Strain) – If no node specified, then average for all nodes in element – Gets at a lot more values, including SMISC, NMISC

• NSOL, NVAR, NODE, Item, Comp, Name, SECTOR – Nodal Data (DOF solutions) – Supports SECTOR for cyclic Symmetry

• RFORCE, NVAR, NODE, Item, Comp, Name – Reaction Forces

• JSOL, NVAR, ELEM, ITEM, COMP, Name – Joint information (U, V, A, Forces/Moments)

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Variable Store Commands: LS-DYNA • EDREAD, NSTART, Label, NUM, STEP1, STEP2 • Reads the various LSDYNA time history files and stores their entire contents into multiple variables. • You specify a starting number (NSTART), not an NVAR • Files: – GLSTAT, MATSUM, SPCFORC, RCFORC, SLEOUT, NODOUT,RBOUT

• NUM defines what item to read – part (MATSUM, RBDOUT) – node number (SPCFORC, NODOUT) – contact entity (SLEOUT, RCFORC)

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Variable Store Commands: Other • SOLU: Stores solution (solver) information – Convergence, and solver parameters

• • • •

CISOL: J-Integral Info ENERSOL: Energies GAPF: Gap Force Data GSSOL: Generalized Plane Strain Length, Rotation, Force, Moment

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What File to Get From • Jobname.rst is the default • You can change with: – GUI: TimeHist PostPro->Settings->File – Tool: File->Open Results – APDL: FILE, fname, ext

• Use this to point to an LS-DYNA *.his file as well

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Number of Variables • By default, in batch, you get room for 10 variables for ANSYS runs – 30 for LS-DYNA – If you are using the Tool, it automatically raises it to 200

• You can raise that to 200, and you get 190 – ANSYS needs 10 of its own

• Has to do with how they very quickly get, store, and access the variables – efficiency • Change from default with: – GUI: TimeHist PostPro->Settings->File – Tool: Automatically sets at maximum – APDL: NUMVAR,nvar

• Recommendation: Just put an numvar,200 in your macros

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Reading in Your Own Variables • Data command – DATA, IR, LSTRT, LSTOP, LINC, Name, KCPLX – Must be followed by a FORTRAN format statement – I can never get this one to work…

• Use APDL Parameters – *TREAD to read into an APDL table array – Use VPUT to convert from APDL array to a Variable – Does not interpolate, you need the same time points as in your NSOL type command - need to find a work around. – Recommended way

• Use ~eui or Tool to read it in – Nice if you are going to do it a lot – Very specific format – See next slide for example

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Tool or ~EUI format • ~eui,'ansys::results::timeHist::TREAD d:\test1\harmonic.prn TESTMID' • ~eui,'ansys::results::timeHist::vputData TESTMID 5' # # # # # # # # # # # # # # # #

TEST DATA FILE EXAMPLE ALL COMMENT LINES BEGIN WITH # Blank lines are ignored The first line without # sign must contain the variable names to be used for each column of data read into POST26. NOTE that for complex data only one variable name should be supplied per (real, imaginary) pair as shown below. The next line can either be left blank or have descriptors for each column such as REAL and IMAGINARY The data itself can be in free format with the columns "comma delimited", "tab delimited", or "blank delimited" The first column of data is always reserved for the independent variable (usually TIME or FREQUENCY) FREQ

1.00000E-02 2.00000E-02 3.00000E-02 4.00000E-02 5.00000E-02 6.00000E-02

TEST1 REAL -128.32 -150.08 -163.12 -147.63 -133.90 -172.38

TEST2 IMAGINARY 0.17764 0.36474 0.57210 0.81364 1.1091 1.4886

REAL 5.6480 5.6712 5.7097 5.7629 5.8298 5.9080

IMAGINARY -4.47762E-03 -8.99666E-03 -1.35897E-02 -1.82673E-02 -2.29925E-02 -2.76290E-02

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The Store Command • When in batch/command line you need to do a STORE command to actually read the results in • STORE, Lab, NPTS – Lab: • • • •

Merge (default). Overwrites Vars that exist, adds new ones New. Replace all data with new definitions Appen. Appends data. Use this when you want to add time segments ALLOC. Creates the data records for npts but does not create any variables. • PSD. Create frequency points for PSD calculations

– NPTS • Number of time (frequency) points.

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STAT •

STAT – Issue a STAT option first, then STAT

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PRINT STAT – Find out your listing options and what variables you have – Default

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DEFINE STAT – Tells you what your settings are and what variables you have defined

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OPERATE STAT – Lists any operation settings you may have, and variables defined

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PLOTTING STAT – Shows the POST26 display settings. DX R13: 02/17/2011 31

Displaying Variables

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Plotting • • • • • •

Most of the time you will be making a line graph Time on X axis, value on Y You can stack multiple Variables Tool: Use the graph button GUI: TimeHist Postpro->Graph Variables APDL: PLVAR

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PLVAR • PLVAR, NVAR1, NVAR2, NVAR3, NVAR4, NVAR5, NVAR6, NVAR7, NVAR8, NVAR9, NVAR10 • Allows you to plot up to 10 variables against each other – Just give the variable number

• Plot controlled by normal graphing controls – Google: focus graphing in ansys

• Related Commands: – XVAR: Allows you to change X axis to a variable – PLCPLX: Change to allow for complex portion of results – PLTIME: Specify time range

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Simple • The number of points you use with store, and your data, determine graph resolution • Great for quick plots • ANSYS Mechanical? – If your code post processing snippet has a /show,png and you make plots, those come back to ANSYS Mechanical

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Listing • GUI: TimeHist Postpro->List Variables • TOOL: Little sheet of paper (List) icon • APDL: PRVAR – PRVAR, NVAR1, NVAR2, NVAR3, NVAR4, NVAR5, NVAR6

• Standard listing commands and controls apply – Google: Tools of Post Processing: Listing focus

• Also EXTREM – It lists the min and max for all variables

• Related commands: – PRCPLX: Display complex values – PRTIME: Time range

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Exporting and Such • If you want to do more you can put variables into APDL table or array and then write it out with *VWRITE • If you “save data” to a file in the Tool, it writes the code for you. – Modify to write as you want – Very easy to read into Excel as fixed width

*DEL,_P26_EXPORT *DIM,_P26_EXPORT,TABLE,160,1 VGET,_P26_EXPORT(1,0),1 VGET,_P26_EXPORT(1,1),2 /OUTPUT,'foo','txt','.' *VWRITE,'TIME','UX_2' %14C %14C *VWRITE,_P26_EXPORT(1,0),_P26_EXPORT(1,1) %14.5G %14.5G /OUTPUT,TERM

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Calculating

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Operations • The calculator has a purpose: you can build calculations with it – Uses standard operators – Variables use their names in {}

• APDL has vector math commands – Add/Subtract/Multiply/Divide – Integrate/Differentiate – Sqrt/Absolute Value /Logs/Exponent, – Find Large/Small

• You can overwrite! – 21 can be used in a calc and be the destination as well

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Example: FSUM • • • •

SQRT of the sum of the squares Do it in the tool using the calculator or by writing in equation Our put in commands Good way to do a script is use calculator, then look at code generated

rforce,11,8,f,x,FX_8 rforce,12,8,f,y,FY_8 rforce,13,8,f,z,FZ_8 prod,14,11,11 prod,15,12,12 prod,16,13,13 add,17,14,15,16 sqrt,18,17 plvar,18 DX R13: 02/17/2011 40

Example: Max Stress on 1,-1 Corner Edges • Grab nodes on top • Stick first node’s S1 into Variable 20 • Loop on remaining nodes – Put S1 into Variable 21 – Overwrite 20 with max of 20 and 21 (LARGE)

• Max is in 21 at end

nsel,s,loc,x,1 nsel,r,loc,y,-1 *get,nnd,node,,count nn = ndnext(-1) ansol,20,nn,s,1 nn = ndnext(nn) *do,i,1,nnd ansol,21,nn,s,1 large,20,20,21 nn = ndnext(nn) *enddo plvar,20 nsel,all

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*GET tools • There is a whole set of *GET commands that read a variable and return a scalar value – *get,myval,VARI,nvar,Item1,Item2 – Item1,Item 2 can be: • EXTREM – Min, max, last value or the time that value occurs at » If nvar 32 is stresses, to get max stress and when it occurs: » *get,mxs,vari,32,extrem,vmax » *get,mxt,vari,32,extrem,tmax – Covariance between two variables

• RTIME,t – Real Values at a given time

• ITIME,t – Imaginary Values at a given time

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Even more with VGET & VPUT • You can also transfer variables into APDL arrays with VGET and the put it back with VPUT • Opens up the full spectrum of APDL array math

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Full List of Commands • • • • • • • • • • • • • • • • • •

ABS: Forms the absolute value of a variable. ADD: Adds variables. ATAN: Forms the arctangent of a complex variable. CLOG: Forms the common log of a variable CONJUG: Forms the complex conjugate of a variable. DERIV: Differentiates a variable. EXP: Forms the exponential of a variable. FILLDATA: Fills a variable by a ramp function. IMAGIN: Forms an imaginary variable from a complex variable. INT1: Integrates a variable. LARGE: Finds the largest (the envelope) of three variables. NLOG: Forms the natural log of a variable. PROD: Multiplies variables. QUOT: Divides two variables. REALVAR: Forms a variable using only the real part of a complex variable. SMALL: Finds the smallest of three variables. SQRT: Forms the square root of a variable. DX R13: 02/17/2011 44

Other POST26 Commands

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Lots more Complex Stuff… • This is a primer, so we are skipping the details on the complicated stuff • Read manual for details

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PSD • POST26 will take Mode Shapes and PSD data and calculate Covariance and Response PSD • Covariance – Get variable for the nodes and quantities you want covariance on – Use CVAR on two variables – Then use *get,par,VARI,nvar,extrem,cvar

• Response PSD – Store PSD file information with STORE,PSD – Get variable for the nodes and quantities you want response at – Use RPSD to calculate the response PSD

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Make Response Spectrum from a Transient Run • RESP command • You create a table with the “oscillator” frequencies in it. – Use FILLDATA or DATA

• You fill a variable with the time dependent result you want a response spectrum for • Use RESP to get U, V, A • See Theory Manual for details • Or run using Tool

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Smoothing Data • • • •

SMOOTH command SMOOTH, Vect1, Vect2, DATAP, FITPT, Vect3, Vect4, DISP Lots of options Vect1 is the Independent value, Vect2 is the time variable – Backwards…

• Vect3 and Vect4 contain the smoothed data after the command is run • Not a button in calculator, you have to type in: – Smoothed_response = SMOOTH ({UY_AT_MIDPOINT},{TIME},2)

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Suggestions & Recommendations

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Crawl, Walk, Run • • • •

Really not very complex But can get complicated bookkeeping wise Use a simple model (ToT…) to prove out your process Remember you can use APDL (VGET/VPUT) if what you are looking for is not in POST26 commands • Get your head around the fact that you are working with data at a point, over time. – Not data at a lot of points at a single time (POST1)

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Working with Mechanical • For many things, probes do what POST26 does • If you are using POST26 as a post processing snippet: – Don’t forget to put a FINISH and /POST26 at the top of your script – Use a /SHOW,PNG to bring back any plots – *get scalar results can also be brought back as parameters

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Resources • Go the Focus Blog (www.padtinc.com/focus) and I’ll post the macro I used and a workbench example – This PowerPoint as well

• The manuals • www.ansys.net – Has some post26 examples. Best is a Bode plot by Bill Bullat

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Thank You… • PADT Enjoys doing these webinars… • Please consider us as your partner • ANSYS Related – – – –

Training, Mentoring Consulting Services Customization Sales (if in AZ, NM, CO, UT, NV)

• Stratasys 3D Printers and Systems • CUBE HVPC Systems • Product Development – High-end engineering with practical, real world application

• Rapid Prototyping – SLA, SLS, FDM, PolyJet, CNC, Soft Tooling, Injection Molding

• Help us by letting us Help you

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