Assigning a string element to a struct in an array of structs

I am writing a function that reads various properties, including a string, from a csv file and assigns it to a relevant element of a struct which happens to be in an array of similar structs.

Whenever I attempt to assign value to:

materialLookup[v-1].name 

the program crashes.

MaterialL 

is a struct with a string element called name that looks like this:

    struct MaterialL {
    string name;
    double sigma;
    double corLength;
    double mu;
    double muPrime;
    double ep;
    double epPrime;
};

I have checked that I am reading the string from the csv file correctly and in this case, it is "Drywall". The program always crashes before I am able to cout<<"hey"; on the next line. My only thought is that because the program doesn't know the size of the string before I assign it, it doesn't leave any memory for it. If so how can I rectify this?

   unsigned int getMatLookUp(string filename)
{
    int nLines = getNumOfLines(filename);
    cout << nLines;
    materialLookup = (MaterialL*)alignedMalloc(nLines * sizeof(MaterialL));
    ifstream file(filename);
    int v = 0;
    string value;

    if (file.is_open() && fileExists(filename))
    {
        //flush title line
        for (int p = 0; p < 6; p++){ std::getline(file, value, ',');  }std::getline(file, value);
        v++;
        //get all the materials
        while (v < nLines -1)
        {
            std::getline(file, value, ',');
            cout << value<<"\n\n";
            materialLookup[v - 1].name = value;
            cout << "hey";
            std::getline(file, value, ',');
            cout << value << "\n\n";
            materialLookup[v - 1].sigma = stod(value);
            std::getline(file, value, ',');
            materialLookup[v - 1].corLength = stod(value);
            std::getline(file, value, ',');
            materialLookup[v - 1].mu = stod(value);
            std::getline(file, value, ',');
            materialLookup[v - 1].muPrime = stod(value);
            std::getline(file, value, ',');
            materialLookup[v - 1].ep = stod(value);
            std::getline(file, value);
            materialLookup[v - 1].epPrime = stod(value);
            v++;
        }
        file.close();
    }
    else
    {
        cout << "Unable to open file when loading material lookup in function getMatLookUp press enter to continue\n";
        cin.get();
    }
    return(0);
}