LibreMecaDesign.lib package¶

Included data¶

• Carbon steel
• Tool steel
• Stainless steel

Adding data¶

Only standard data from reputable and trusted sources are and should be used in the librairies.

For materials properties, data should include in this order :

1. normalized name
2. aliases (commercial or usual names, comma separated)
3. treatment (e.g. molded, rolled, normalized, etc.)
4. chemical formula
5. modulus of elasticity (E, in GPa)
6. modulus of rigidity (G, in GPa)
7. Poisson’s ratio (nu)
8. volumic mass (often called density, in kg/m³)
9. tensile yield strength at 0,2 % (S_y, in MPa)
10. ultimate tensile strength (S_ut, in MPa)
11. thermal expansion coefficient (alpha, in µ/°C)
12. brinell hardness
13. Rockwell B hardness
14. Rockwell C hardness
15. fatigue strength at 5E8 cycles (S_f, in MPa)
16. elongation at break (epsilon, ratio)

A .csv template is provided in the lib root.

1. Check and ensure such data don’t already exist to avoid duplicates
2. Use the provided .csv template and open it in your favorite spreadsheet editor
3. IMPORTANT ! Use the same exact order of columns and symbols headers
4. Ensure values have a correct number format in the final CSV file :

• numbers should use dots . as decimal separator
• numbers should not be into quotation marks “” meaning their format in the spreadsheet should be number
• numbers should not use thousands separators

1. Include the data source (organization, book, etc.) of your data in the 1st line of the header. It will be used in the database as a comment and to ensure the trustability of the data
2. Give your final CSV file a relevant name like material.csv. For example : stainless-steel.csv, carbon-steel.csv, cast-iron.csv This name will be added into the database in the category column.
3. Try to split your data into consistent files to keep less than ~ 100 entries in each files (for maintainability)
4. Save your file into the proper directory : the one mentioning the source organization of the data or the standard used to compute/measure the data : ISO, ACNOR, SAE, ASHRAE, etc.

lib.build.SI_convert(line, prop)[source]¶

Convert usual engineering units & multiples to SI units to normalize database

Note

the units and multiple handled from the CSV data-sheet are considered given in usual engineering habits (GPa, MPa, etc.) because they are human-readable and standard tables are given is such units. However, to make the database unit-independant and facilitate later querying, multiples have to be normalized into SI standards.

lib.build.build_property(prop)[source]¶

Sequence of functions to build a new property into the database

lib.build.check_pattern(line, prop)[source]¶

Check and ensure that the properties are given in the expected order to avoid mixing up the columns

Parameters:	line (str list) – the header line corresponding to the symbols of the given columns prop – the desired property to check
Returns:	raise an error if given and expected headers don’t match

lib.build.create_tables(cursor, prop)[source]¶

Create the relevant tables into the database

Parameters:	cursor – sqlite 3 cursor prop – the desired property - for now : “materials”

lib.build.database_handle(db)[source]¶

Create or overwrite the sqlite3 database and open a connection if it does.

Parameters:	db (str) – database filename
Returns:	connection socket to the sqlite3 database

lib.build.insert_property(prop, cursor, comment, category, line)[source]¶

Build the database insertion with the relevant formatted data

Parameters:

prop (string) – the property to build cursor (sqlite3 handler) – the database cursor handler comment (string) – the comment to add in every insertion, namely : the source of the data - should be the first line of the CSV data-sheet category (string) – the category of the property to add. For exemple : cast iron, stainless steel, carbon steel, etc. line (list of strings) – the data line from the CSV data-sheet

lib.build.parse_csv(PATH, cursor, database, prop)[source]¶

Parse the CSV files and process their data

Parameters:	PATH – root of all the librairies cursor – sqlite3 handler database – sqlite file prop – the given property

Reference¶

Machine Design, an integrated approach. Robert L. Norton, Prentice Hall. Fifth Edition, 2014.

Résistance des matériaux. Bazergui, Bui-Quoc, Biron, McIntyre, Laberge, Presses internationales Polytechnique. Third Edition, 2002.

General consideration¶

For beams, use the x axis along the longest dimension of the beam. Thus the cross-section of the beam will be in the (y, z) plan.

class lib.geometry.geometry(**kwargs)[source]¶

Store and compute basic geometrical properties of a material object

Parameters:	position (3 elements array or tuple) – coordinates of the origin of the object. For example, the centroid of an extreme surface dimensions (3 elements array or tuple) – lengths over the 3 space dimensions or formal expressions of these dimensions. a,b – geometric parameters to compute section properties for standard/usual profiles as defined in Norton’s Machine design book.

circle()[source]¶

Parameters:	a – radius b – none

hollow_circle()[source]¶

Parameters:	a – external diameter b – internal diameter

rectangle()[source]¶

Parameters:	a – height b – width

right_triangle()[source]¶

Parameters:	a – height b – width

semi_circle()[source]¶

Parameters:	a – external diameter