# Category : Science and Education

Archive : MECHAN93.ZIP

Filename : HELP.BAS

Main HELP file to describe use of MECHAN programs³ HELP - Last modified January 21, 1993"ù"The latest version of MECHAN is version 93-1 January 21, 1993 "ÿ(H2"MECHAN is a general purpose INTERACTIVE program for the kinematic"<"and dynamic analysis of single degree-of-freedom MULTI-LOOP"ÑF"planar mechanisms which can be assembled from combinations of " P"linkages, sliders, spur gears, springs and dampers."ZUd"MECHAN was developed by Professor Charles Radcliffe at the "n"University of California at Berkeley for use by his students"Øx"in classes on Kinematics and Dynamics of Machinery." : "The set of programs has also been useful to design engineers"f"in industry who need to verify their models of linkages and gears."¨"The author has checked the accuracy of the calculations by"ð "comparison, where possible, with results from graphical or other"ª"textbook solutions."´Z¾"No guarantee is given or implied for the accuracy of calculations"£È"related to actual machinery and the results obtained using MECHAN"èÒ"should always be checked against other solutions or test data"ÿÜ"as appropriate."æð ¤Oú"The MECHAN programs are distributed as BASIC source code""and run in INTERPRETER mode under GW-BASIC version 3.2."Í"The programs make extensive use of the CHAIN command to""share data between programs. The MECHAN programs were"M""developed many years before BASIC compilers or QUICK BASIC","became available. The author has considered converting to"Ô6"QUICK BASIC but has decided to go by the old advice ... If it"@"ain't broke don't fix it. We are aware that the code is"RJ"an excellent example of 'spaghetti code' but it works."XT^"GW-BASIC 3.2 does not know about VGA displays but a VGA display"ßh"should support the EGA mode (screen 9) without problems."år*|"To get hardcopy of a SCREEN display you must run GRAPHICS.COM"p"before using the PRINT SCREEN key to print the SCREEN display."°"The hard copy may be a bit distorted depending upon your"ó"SCREEN/PRINTER combination. See instructions under GRAPHICS";¤"in the MS-DOS ver 5.0 User's Guide. With VGA/EGA color displays"t®"a screen capture program may give better results."¸: ¤§Â" The INIT file FORMAT " : óÌ"Before using MECHAN check the INIT file. This file contains a single"?Ö"line in the format 'D:','1',20,1. Where 'D:' is the disk drive where"à"you wish to have data files stored. The '1' selects the default"¬ê"for the display resolution. "²ôëþ" 1= screen 9 ... EGA (640x350) color display"$" 2= screen 2 ... CGA (600x200) mono display."*k"The number 20 is the maximum number of positions allowed."¯&"This number sets the dimensions of the many data arrays used"ô0"and shared by all of the programs. Reduce to 15 if you get an"3:"OUT OF MEMORY message. Try 20 for kinematics only data."9DhN" 15= maximum for DYNAMICS problems."X" 20= maximum for KINEMATICS problems."bål"The last number suppresses the information displays if set = 0"ëv3 "To create or change the INIT file enter INIT at the DOS prompt."9C ¤"The program does all calculations in closed-form and relies"±¨"on the concept of KINEMATIC GROUPS."·²ý¼"A kinematic group is a combination of links, sliders, or gears"I Æ"which forms an independent component of multiloop planar mechanisms."O Ð Ú"Each of the groups can be analyzed for accelerations and/or"Ý ä"forces and torques as an independent problem solved in closed-form."'!î"The analysis of many complicated mechanisms can be subdivided into"o!ø"a series of simple problems where the results of the analysis of"º!"previous groups are available as input data for the analysis of the"ä! "next group in the kinematic chain."ê!2" "It should be noted that only single degree-of-freedom mechanisms"v"*"can be analyzed by MECHAN. However, a large majority of the"¿"4"mechanisms used in machinery fall in this category and MECHAN has"#>"been designed to be a fast and reliable method for the dynamic"Q#H"analysis of such mechanisms. If you suspect an error in the program"#R"please send me the problem statement and printout of your results"Â#\"and we will resolve the problem."Ð#f : ¤$p"In MECHAN the terms GROUP and COMPONENT are synonymous."$za$"A mechanism will be assembled and analyzed as a series of components"$"with the kinematic analysis proceeding in sequence from the input to"Û$"the output component of the mechanism."á$¢$%¬"Dynamic analysis begins with the output member and proceeds"_%¶"in reverse sequence from output to input component."e%À¨%Ê"A named data file is created for each problem to be solved."î%Ô"This data file is created interactively with the user prompted"&Þ"for each data item to be entered."&èe&ò"Each problem may have three associated data files with the same "&ü"primary file name:" &Ê&" filename.DAT ... contains geometric, mass, and input data."'" filename.PLT ... a copy of the RESULTS file from a previous"R'$" run. Used by graphics postprocessors."'." filename.XLD ... data file with external loads acting on each"à'8" member for each position of the mechanism."î'B : ¤(L : "DATA ENTRY IS A FOUR STEP PROCEDURE:"$(VW(`"1 - Define fixed points and their location."](j¦(t" A 'precision point' is a fixed point drawn as a small circle"å(~" on the display screen without the base structure. " )" May be useful for checking synthesis problems."&)d)"2 - Define the sequence of components to be assembled."j)¦´)°"3 - Define the geometric parameters which describe each component."º)ºý)Ä"4 - Define the inital input motion parameters and the range"*Î" of the input motion."#*Øi*â" A FILENAME.XLD data file can created with any ASCII editor."°*ì" Don't forget to use a comma between data items on each line."¶*öÐ*" See next page."Þ*

: ¤ä*+" USER-DEFINED EXTERNAL LOADS" : Z+(" The user must define the system of external loads in an *.XLD"¡+2" file. Each line describes a load F and pure couple Torque"ì+<" in position J acting on member L at point N in comma-separated",F" format: J, L, N, Fx, Fy, Torque"",Pe,Z" The Q-array used in DYNAN contains all external loads ",d" force-torque information." : Ù,n" All elements of the Q-array are initialized = 0 at the start.""-x" The *.XLD file contains data for non-zero forces or torques."(-r-" In earlier versions of MECHAN an extra DxF term was required."¹-" The DxF entry is the moment of external loads Fx and Fy at". " point N acting about the cg of member L. This term is now "G.ª" computed in DYNAN and need not be supplied except as noted"}.´" below when using data in the 1988 format.".¾È.È" So-called INERTIA FORCES are accounted for automatically"/Ò" and should NOT be a part of the filename.XLD file."

/Ü/æ ¤T/ð" MODIFYING 1988 FORMAT *.XLD FILES TO 1990 FORMAT"Z/ú¤/" If N=0 in a data record the data is assumed to be in the 1988"ì/" format with Fx= sum of the x-forces on member L, Fy= sum of"40" y-forces on member L, Torque= net pure couple, and DxF= the"}0"" moment of Sum-Fx and Sum-Fy about the cg. The value of DxF "Â0," was not computed and a point N was not required in 1988." 16" The 1990 format is more logical and hopefully more useful."1@W1J" To modify a 1988 *.XLD data file you must add a zero as the"1T" third data item in each line and reverse the order of DxF"æ1^" and Torque entries. The 1988 *.XLD files were in the format"ì1h2r" J, L, FX, FY, DxF, Torque""2|U2" The 1990 *.XLD files are in the format"[22" J, L, N, Fx, Fy, Torque"2¤Ù2®" Joint forces are internal forces and are calculated in DYNAN."ß2¸é2Â ¤ï2Ì-3Ö"COMPONENTS AVAILABLE FOR KINEMATIC OR DYNAMIC ANALYSIS"33ào3ê" 1 - Input crank (link rotating about a fixed point)"¹3ô" 2 - Input slider (straight-line motion in an arbitrary direction)"þ3þ" 3 - Input cylinder (pivoted cylinder driving an input crank)">4" 4 - Point on a rigid body (multiple points are allowed)"X4" 5 - Two-link dyad"4" 6 - Oscillating slider (turning block)"¹4&" 7 - Rotating (or fixed) guide with slider"50" 8 - Two spur gears with connecting arm and driven point on 2nd gear"65:" 9 - Linear spring between any two points"h5D"10 - Viscous damper between any two points"v5N : ¤|5X5b"LIMITATIONS" : µ5l"1. Kinematic Analysis " : õ5v" The mechanism must be assembled from components which">6" can be analyzed sequentially. Kinematically complex mechanisms"6" which require the solution of a set of nonlinear equations"»6" cannot be analyzed by this version of MECHAN."Á6á6¨"2. Dynamic Analysis " : %7²" The program does not solve for the 'time response' due to"k7¼" the application of a set of external loads. It is limited "¨7Æ" to the so-called 'kineto-static' problem where the"î7Ð" accelerations are known and the driving force or torque and"*8Ú" the unknown internal joint forces are calculated."08ä>8î : ¤D8ø]8"SYMBOLIC NOTATION"c8 ¨8"Before you use MECHAN you must have some familiarity with the"ê8 "notation used. Each point (or joint) in the mechanism is ".9*"given a 'point number'. Each member (rigid body) is given a"r94"'member number'. Before you start YOU MUST HAVE A SKETCH of"¶9>"of the mechanism to be analyzed with all point numbers shown"ü9H"and all members numbers circled so as not be confused with the":R"point numbers.":\^:f"A typical component has three points which must be identified."¡:p"Points numbered N1 and N2 are points with specified motion."§:zð:"The motion is typically 'specified' as the result of the analysis"6;"of a component (group) which occurs earlier in the sequence of";"components which determine the geometry of the complete mechanism.";¢Ç;¬"Point N3 is a point (or joint) whose motion is calculated"<¶"by the code associated with the component in subroutines"<À"KINAN or DYNAN.",<Ê : ¤x<Ô"Each member (rigid body L) has a reference R-vector, R(L), extending"Ã<Þ"from point N1 to N2. Additional points N3 on the member L are des-"=è"cribed by S-vectors which locate points N3 relative to the R-vector."X=ò"The angle B(N3), measured counterclockwise from R(L), locates the"=ü"point N3 at a distance S(N3) from point N1."= Ó= "In dynamics problems the members which are external to the"> "current component (group) at joints N1 and N2 are described"[>$ "as EXTERNAL MEMBERS. This implies that the joint forces are">. "external to the current component and must be accounted for"â>8 "in the same manner as the forces described in the *.XLD file"$?B "for the current mechanism. This is all done automatically"m?L "by MECHAN once the structure of the mechanism has been described."{?V : ¤¿?` "As an example, consider the kinematic analysis of a four-bar"Ó?j "linkage." : @t "STEP 1: Specify the location of the two fixed points."T@~ : " Points 1 and 4 are arbitrarily defined as fixed points."@ " You will be prompted to enter point number followed by"Ç@ " the X and Y coordinate of each fixed point."ø@ : "Try Point 1 at 0,0 and Point 4 at 3,0"þ@¦ CA° " A 'precision point' is a fixed point which will be displayed"Aº " as a double circle without a fixed base symbol. It is used"ÁAÄ " when checking the results of a synthesis problem."ÇAÎ ÑAØ ¤Bâ "STEP 2: Define the sequence of components to be used."Bì MBö "Sequence number Component number Component name"SB

B

" 1 1 Input crank"ÃB

" 2 5 Two-link dyad"ÉB

ÓB(

¤ C2

"STEP 3: Define the geometry for each component. "C<

7CF

" INPUT CRANK GEOMETRY" : mCP

"The geometry of the input crank is defined by:"sCZ

´Cd

"N1 - the point number for the input crank fixed pivot = 1"õCn

"N2 - the point number for the input crank moving pivot= 2"6Dx

" L - the member number for the input crank = 2"|D

" R - the length of the input crank = 1 unit"D

ÃD

"Note that the location of point 1 was defined earlier and"E

"the units for length are arbitrary but must be consistent."Eª

PE´

"Member number 1 is ALWAYS the fixed reference member or base."VE¾

`EÈ

¤fEÒ

EÜ

" TWO-LINK DYAD GEOMETRY" : ÆEæ

"The geometry of the two-link dyad is defined by:"ÌEð

Fú

"N1 - the point number for the first reference point = 2IF" The motion of point 2 will be calculated during"F" the kinematic analysis of the input crank."ÂF"N2 - the point number for the second reference point = 4"ýF"" The motion of point 4 was defined earlier when"9G," it was declared a fixed point (vel and acc = 0)"{G6"N3 - The point number for the common point of interest = 3"½G@" M - Mode of assembly (+1 or -1) = 1"ûGJ" Positive mode describes assembly of point N3 at a"9HT" location defined by a positive (counterclockwise)"pH^" rotation of the vector N1-N2 toward N1-N3."²Hh"L1 - The member number connecting N1 to N3 = 3"ôHr"L2 - The member number connecting N2 to N3 = 4":I|"R(L1) - The length of member L1 = 2.828"|I"R(L2) - The length of member L2 = 2"I : ¤I¿I¤ " INPUT CRANK MOTION PARAMETERS" : øI®"The input crank motion parameters are defined as:"þI¸9JÂ"Initial input crank angle in degrees = 0 (deg)"zJÌ"Initial input crank angular velocity = 628 (rad/sec)"½JÖ"Input crank angular acceleration = 0 (rad/sec/sec)"Kà"Number of times to increment the input crank angle = 13"CKê"Increment for the input crank angle in degrees = 30"IKôKþ"The value of 13 insures a complete revolution." K K K ¤K& »K0 " DATA FILE NAMES" : þK: "The named input data file is saved with a .DAT extension. "LD CLN "For example the data file for kinematic analysis of our"LX "four-bar linkage might be named FRBR or FOURBAR or FOUR, etc."Lb ÔLl "The .DAT extension will be added automatically by the program."ÚLv

M "The data file would be saved as FOUR.DAT"M : ¤M EM "RESULTS GENERATED AND DISPLAYED"KM¨ M² "The program will calculate and display angular position,"ÌM¼ "velocity, and acceleration for each moving member and the"NÆ "linear x-y motion components for each point in the mechanism."\NÐ "The normal response is N (NO) to the question DO YOU WANT PAUSES ? "NÚ "in the display of output. All of the output"ÑNä "is automatically written to a file named RESULTS. If you"

Oî "wish to examine each table of results as it is being"SOø "generated answer Y (YES) but be prepared to press RETURN after"sO

"each table is displayed."yO

¿O

"Beginning with Version 90-3 you have the option of suppressing"P

"the display of tables of results. The information continues"JP*

"to be written to the file RESULTS and can be viewed later using"P4

"program SUMMARY. This option will reduce the calculation time"¦P>

"by almost 50%."´PH

: ¤ºPR

ÑP\

"GRAPHICS OUTPUT"×Pf

Qp

"Program MECHDR is a graphics postprocessor which will read"\Qz

"coordinate information from either the current RESULTS file"Q

"or a file with a .PLT extension. If you wish to save the "ÞQ

"current RESULTS file as a .PLT file you must exit to DOS"R

"and use the DOS command COPY RESULTS FILENAME.PLT."R¢

cR¬

"MECHDR will display the mechanism in either the first or the"«R¶

"sequence of positions. You can single-step through the sequence"íRÀ

"or display all positions overlayed in a repeating pattern."óRÊ

3SÔ

"MECHPL will create x-y plots of any variable versus any "tSÞ

"second variable. This allows the user to make plots with"Sè

"axis labels such as:"Sò

ÐSü

" ANG ACC OF MEMBER 3 vs ANG POS OF MEMBER 2 , or"T" X-POSITION OF POINT 5 vs Y-POSITION OF POINT 5 , etc."TTT"Use the PRTSC key to get hard copy of tables or graphs."bT$ : ¤hT.©T8"Data entry for a DYNAMICS problem is essentially the same"êTB"as for a KINEMATICS problem with added entry of the mass "*UL"and centroidal moment of inertia for each moving member."0UVpU`"Remember that for 1988 you can define the external loads"´Uj"in an .XLD file prepared using any ASCII editor. Each line "äUt"has data for one position of one member."êU~.V"Beginning with version 1988-4 (November 1988) the SPUR GEARS"qV"analysis has been improved so that either the input gear or"³V"the arm can be moving members. This allows the analysis of"úV¦"general geared linkages. See, for example, GEAR4BAR or GEAR5BAR"W° CWº"Examine the first line of any .PLT or RESULTS file and you"WÄ"will note that the RESULTS file has knowledge of whether or"ÇWÎ"not the file was generated by either kinematic or dynamic" XØ"analysis. The input data is stored in a file with the .DAT"QXâ"extension. The .PLT and .DAT files should have the same prefix."_Xì : ¤Xö"USER QUESTION and ANSWER" XÈX

"The most often asked question is 'How do I analyze a simple"

Y"Slider-Crank mechanism?'. The most common error is an attempt"UY"to use the oscillating slider in the analysis. The Slider-Crank"Y("mechanism is an INPUT CRANK driving a ROTATING GUIDE. The"áY2"guide just happens to have zero angular velocity and acceleration."(Z<"This is easily arranged by giving the guide a member number= 1."[ZF"Member number 1 is ALWAYS the fixed member."aZP£ZZ"The reference point on the guide must have been previously"åZd"defined as a fixed point. This point must not fall on the"#[n"same position occupied by the input crank fixed pivot.")[xl["*.DAT files for earlier versions may not run for a dynamics"["problem but will probably be OK for a kinematics problem."Ý["If you have difficulty reenter the data."ë[ : ¤ñ[ª/\´"I hope you find the program useful. If you find a bug"r\¾"let me know and I will check it out and correct the code if"±\È"necessary. Please do not make corrections to the code."ó\Ò"These programs have grown through three separate operating":]Ü"systems and are difficult to decipher. Some day I will convert"u]æ"to a more readable version. In the meantime I hope"]ð"you find the programs useful." ]úã]"You may make as many copies of the distribution disk as you"%^"wish and distribute them freely to students or colleagues."+^e^""Students need not register until after graduation."k^,^6"Charles W. Radcliffe"½^@"Professor of Mechanical Engineering (Emeritus)"é^J"University of California at Berkeley"_T"571 Silverado Drive" _^"Lafayette, CA 94549"&_hf_r"Telephone: (510) 283-1528 ... Leave message if no answer"¥_|" FAX: (510) 283-1528 ... Call first to allow setup"Î_ "Press SPACE-BAR to restart MECHANê_Q$çÞ : ÿ(Q$)ç Í ø_"MECHAN"2`¤"Press

Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/